News Check out all the latest news here on my 'News' page. Got any questions? Then just contact me. Transformer Coupled Interface Type 1 Unbalanced to Balanced Converter23 June 2021I've been building these things for years and after so many customers suggested that I should release my TCIs commercially, I decided to take the plunge. So here's my Transformer Coupled Interface Type 1 which is a 2-channel, passive, unbalanced to balanced converter. The title says it all, but there's a lot more information about unbalanced to balanced conversion in my post, here.... RE-MPG-80 Rack Ears for the Roland MPG-805 May 2021This has been a long and frustrating wait as ever since I launched my RE-MKS-70 and RE-MKS-80 replacement rack ears, I’ve had enquiries to make similar kits for other products, so I’m pleased to announce my RE-MPG-80 rack ears for the Roland MPG-80. I bought my MKS-80 off my employer, Roland (UK), in 1989. Even with staff discount, this thing was quite expensive and when you consider that I’m actually a guitarist, the purchase was even more questionable. Ah well… Prior to computer editors, let alone third-party controllers like the Retroaktiv MPG-8X, why on earth then, didn’t I also purchase a MPG-80 at the same time? Sex, drugs and rock ‘n’ roll? Who knows? So, thirty-two years later, a lovely customer of mine who recently acquired a Retroaktiv MPG-8X, put up his Roland MPG-80 for sale. I made Dan an offer which he conditionally accepted, the condition being that I service his latest acquisition; a Roland SH-101. Well, I said I'd have to think about it... for like five seconds, LOL and then we shook hands. 🙂 You can read all about Dan's SH-101 service, here. Dan’s MPG-80 was pristine and had been serviced before he bought it. Hence my keenness to grab this particular example. I now have a hardware controller for my beloved MKS-80 but… more importantly, I have rack ears! YAY!!!! I can now design a pair of rack ears for this box and keep some of my customers happy. Just like the originals, my RE-MPG-80 rack ears for the Roland MPG-80, are made of 2mm mild steel and are powder coated with a lush, matt black finish. They fit perfectly and look great. I’m really happy with what Lenton Engineering has produced. Supplied with black M5 machine screws, all you need is a pozidrive screwdriver, to get these fitted to your own MPG-80 in a couple of minutes. The number of MPG-80s and indeed MKS-80s, on the planet is shrinking, so the market for custom replacement parts and upgrades is inclined to follow a similar path. I therefore only get things like the RE-MPG-80 rack ears, made in small batches.... V06 Roland MKS-80 Broken Data Cartridge Slot Fix23 April 2021Over recent years, I’ve seen quite a few Roland MKS-80s and many have a broken data cartridge slot. At last, there’s a solution; my V06 Roland MKS-80 Broken Data Cartridge slot fix! After more than three decades, the hard plastic from which the enclosure is made, has become very brittle and it doesn’t take much to break the screw pillars that secure the enclosure to the front metal chassis. The data cartridge slot assembly comprises two halves. The back half has a female contact strip which mates with the male contract strip in the cartridge. It’s soldered to a small PCB. Long screws attach this section to the front half which has the flap. The front half in turn, is secured to the metal front chassis via two M3 screws (one on top right and one at bottom left) that go through two small plastic flanges which are part of the front cartridge slot assembly. The problem is that when inserting a data cartridge, you’re pushing the cartridge slot away from the front chassis and the small plastic flanges through which the screws pass that secure the front half of the slot assembly to the front panel, are stressed. The most obvious fix is to use a type of cyanoacrylate (super-glue) or epoxy adhesive to repair the broken flanges. Only thing is, those flanges often break into several pieces. It’s a nightmare! If your data cartridge slot is intact, then you really (REALLY) want to avoid this ever happening. Back in 1984, Roland should have designed the assembly such that it is properly supported from the rear. Well, my V06 bracket continues where Roland left off and does just that! Designed to sit neatly on top of my Aurora Board B (or Board Bx), the V06 provides a physical resistance behind the data cartridge slot, thereby reducing the force on the front slot assembly screw flanges, the only things that are holding the whole data cartridge slot in place. The very front of the assembly, is designed such that it 'rests' on the MKS-80 front panel slot cut-out. This means that so long as there's something sold behind the assembly (like the V06), it's not going to move from side-to-side, let alone backwards and forwards. If the data cartridge slot in your MKS-80 is just fine and you’re interested in Aurora, then you really should consider fitting the V06 bracket. Instead of relying solely on the enclosure’s two screws and the integrity of the screw flanges, the V06 will provide substantial protection against breakage. The V06 bracket has a convenient cut-out which allows access to the voltage measuring pads for the Aurora Board Bx’s on-board Live Forever battery. That’s right, you don’t have to remove the V06 to check the battery voltage on the Aurora Board Bx! Hey, you don’t even have to remove the V06 if you need to ever change the Aurora Board Bx’s CR123! How cool is that? I wish I thought of the V06 when I designed Aurora but all this stuff is kind of an evolutionary process. The Aurora Board Bx for example, didn’t happen until several months after Aurora was released. The two power supplies I’ve subsequently designed for other vintage synths however, both included my on-board Live Forever battery mod, from conception. When I did come up with the idea of V06, I wanted something that could be retrofitted, a solution which existing Aurora customers could purchase and easily install themselves. V06 is just so easy to fit: Just peel off the sticky tape protectors and attach the two rubber strips to the back of your data cartridge slot PCB (as shown below), in the two areas free of solder joints. Replace the four M3 nuts that secure Aurora Board B or Board Bx, with the 20mm M3 stand-offs supplied with the V06. With one hand, line up the data cartridge slot with the slot in the MKS-80 front panel and then with the other hand, slide the V06 plate on to the four stand-offs. Push the V06 plate forwards towards the data cartridge slot and use the M3 nuts you just removed, to secure the plate. Job done! With just a M3 (5.5mm) nut-runner and no disconnecting of internal headers or soldering, once your MKS-80 is open, V06 can be installed in a couple of minutes. So now, Aurora offers the following long-term solutions for the Roland MKS-80: Reliable, smooth, quiet power supply. Live Forever memory back-up battery. V06 Roland MKS-80 broken data cartridge slot fix. Now that’s cool! 😀 NOTE: V06 can only be installed into a Roland MKS-80 that’s fitted with Aurora. V06 is supplied with all fixing hardware. All you need is a M3 (5.5mm) nut-runner. If you have already bought Aurora and would like a V06, please just get in touch. UPDATE - 4th May 2021 Back in the eighties, Jed Allen and I used to work together at Roland (UK), so imagine my surprise when he called asking if I could fit an Aurora into his MKS-80! Jed's machine was in really good condition apart from the data cartridge slot which was very broken. In fact Jed told me that it had been bust for decades and that no one could fix it. Hmm... So while I was installing his Aurora, a little deep thought and I came up with the idea of the V06 bracket. Jed kindly agreed to me keeping his machine for a few more days while I designed and had made the V06 (hey, what are friends for) and of course he became my very first V06 customer. Apart from the pictures of the intact data cartridge slot assembly, all the other pictures are of Jed's MKS-80 and the V06 that went into it. And YES, that's Jed's Roland Juno-60 in the background, which I serviced at the same time. 🙂... Roland SH-101 Service3 April 2021Recently, one of my regular customers put his Roland MPG-80 up for sale, having acquired a Retrtoaktiv MPG-8X. I’ve always, always wanted a MPG-80 to (obviously) go with my MKS-80 but I’ve never seen one in the kind of condition I’d like. Dan’s MPG-80 however, was pristine so I made him an offer which he conditionally accepted, the condition being that I provide him with a Roland SH-101 service. Dan told me that he’d picked it up at a knock-down price but although cosmetically things seemed okay, some sliders weren’t working properly, some keys were intermittent as well as similar problems with power. Hmm… Okay, let’s have a look. Well, when I took this thing apart, I was shocked to see the dust and grime within. On top of that, it had sustained fluid damage and from what I could tell, twice! This SH-101 was completely full of crap! It was clear that this poor ol’ gal had been kept in a smoker’s environment. The pads that cover the switches, just crumbled. That’s right. Tobacco smoke doesn’t just discolour, it reacts with certain materials, making them stiff and brittle. It was no surprise then, to suss out why some keys were intermittent and why some sliders had quite poor performance. Dan, this is a little more than a standard Roland SH-101 service, mate! I stripped the whole machine so as to wash the knobs, buttons, slider caps, keys and even the plastic top-case. With the afore mentioned exposure to smoke, I was very concerned that the keyboard contact strips would break as I removed them but I got lucky. There were a few dry joints which were to be expected and some of the sliders couldn’t be cleaned and therefore required replacement. While I was at, I also cleaned the sockets hoping that they would be okay. Dan supplied me with a power switch which I fitted but I also changed the DC input jack as the original seemed lose and let’s face it, after thirty-something years, why not? After a gruelling seven hours, Dan’s SH-101 was back together again, so time to fire up. The machine switched on first time. Playing around the the DC input, power now was stable. Although I had sound, the HOLD function was stuck on. This is a relatively common problem and is often caused by the HOLD jack socket being stuck open. I’d already checked the sockets and quickly traced the source of the issue to a dry-joint that I had missed. After an extensive testing of all functions, it was time to flip the machine over and recalibrate. As it turned out, things were quite good and I ended up not doing too much at all. It’s unfortunate that the plastic pillars used to secure the metal bottom-case to the top-case, are so fragile. During my thirty years of fixing SH-101s, I haven’t yet found a way to cost-effectively and reliably repair these. Fortunately, so long the majority of them are intact, it’s not too much of a problem. One of the pillars that secures the metal bottom case to the keyboard chassis was missing and the other had an incorrect self-tapping screw rammed into it at some point in its life, which has completely ruined it. The original pillars are very hard to come by and with a couple of the internal plastic pillars broken, it was important to ensure that the bottom-case is properly secured. I therefore fitted brand new M3 PCB spacers to the keyboard chassis, in place of the original pillars. Of course, I also had to dig out a couple of nice, shiny black M3 machine screws. It all ended up very secure and looking very tidy. Kept near a heat source at some time, the battery compartment cover had warped slightly. The deformation was subtle but resulted in the cover sitting ever so slightly proud of the top of the top-case. Not too big a deal, in fact it’s hardly noticeable. I was tempted to gently heat the cover to see if I could make it straight again but these things are so fragile, I decided against it. There’s a lot of talk on-line about the infamous Roland SH-101 discolouring. The SH-101 was released in three colours; red, blue and grey. ALL versions discolour and no one really knows why. Exposure to ultraviolet (sun) light seems to be the most common opinion but my own SH-101 has been kept in an artificially lit, smoke-free environment for most of its life and is now more pink than red! I can understand why people blame UV, however. Removing the battery compartment cover reveals the ‘original’ colour of your SH-101 suggesting that everywhere else which is of course exposed, will be discoloured by ambient UV. Oh well, just one of those weird mysteries of life, eh! Another slightly annoying issue with the SH-101 is that it's very GROOVY!!!!! Yes, that's right. Those nicely aesthetic lines cut into the top-case add to the SH-101's cool look but they also gather all sorts of dust and crap over the years. Even if kept in a nice, clean environment, the grooves in the SH-101's top case do get dirty and getting it out can make a Roland SH-101 service a little longer than anticipated. 🙁 The brittle plastic, the weird decolourisation and the dirt gathering grooves in the top case don't of course detract from the SH-101's attributes. That classic analogue, mono-synth sound and the pure ease with which it can be manipulated, are what the SH-101 is really all about and perhaps decades after its launch, the niggles now simply add to its cute character. Anyway, at long last, this Roland SH-101 now looks, feels and sounds fantastic. Nice and shiny, smooth and responsive controls and a solid keyboard, it's almost like new! It's always really exciting for me, when customers come over to collect their gear and I know Dan's busting to check out his refurbished Roland SH-101. 🙂 Launched in 1983, the humble but amazingly well-known and popular Roland SH-101 is pre-MIDI not that many seem to care! Being equipped with CV however, means that the SH-101 can be controlled by another source and as many of my customers will know, my favourite MIDI gadget / upgrade manufacturer, Kenton Electronics, offers a couple of options to to get your SH-101 controllable via MIDI. The SH-101 MIDI CV kit for example, is installed into your SH-101 and although requiring holes to be cut into the case for MIDI sockets, it does mean that you won't have another box floating around. Kenton also makes a range of stand-alone CV / MIDI converters like the USB Solo, Pro Solo Mk 3 and Pro 2000 Mk 2. These gadgets are very fast and accurate and don't require any modifications to your synth's case. I've already mentioned that I've always been a big fan of Kenton's products, so if you do want to get your SH-101 connected, then I strongly suggest you check out their MIDI / CV converters, here. As well as owning a SH-101 myself, I've worked on hundreds of them over the years and know this Roland classic, inside-out, so if you've got one that's in need of a service or if it just needs a little TLC, please don't hesitate to get in touch. 🙂 Read more about the Roland SH-101 here: Vintage Synth Explorer - Roland SH-101 Roland Icon Series - SH-101 "Hang on a minute. What happened to the MPG-80?" I hear you ask. Well I'm lovin' it but... I now had a template for my RE-MPG-80 replacement rack ears. YAY!!!! You can read about them here.... Hiwatt Amps Found in Pyramid1 April 2021A couple of months ago, one of my regular customers called me in a blinding panic telling me all about these Hiwatt amps that had been found in a pyramid excavation and how he’d acquired them. For a civilisation that didn’t invent the nail, this was truly a remarkable find. Adrian explained that the tomb in which the amps were found, was that of the previously unknown Pharaoh Rokatiti. Having been targeted by tomb raiders at some point, archaeologists believe that the amps remained untouched for the simple reason that no one knew what they were. The amps in question were DR-103s and Adrian couldn’t think of anyone better qualified and experienced to have a look at them, before they were switched on. We arranged a COVID friendly drop-off and a couple of weeks later, after making some space in my schedule, I was able to check out these beautiful amps. As expected, both of them were full of sand, like SERIOUSLY FULL OF SAND. One had been modified and had holes drilled in the front panel and in the serial number plate on the rear panel. Most unfortunate but there didn’t seem to be too much wrong with either of them, at least not on initial inspection. Having been dormant for almost three thousand years, the first thing I did after cleaning them up, was to check the ON / OFF and STANDBY switches. The switches on one of the amps looked particularly bad and although I wanted to keep things as original as possible, I also wanted these amps to actually work... and safely. As I proceeded, some hardware just crumbed and I had to replace a lot of screws, all of which were understandably but annoyingly imperial and not metric. The fuses in both amps were intact suggesting that things were okay last time they were used. My main concern was the output transformers. A couple of resistors had to be replaced as they either broke or crumbled, too. That led me to check other components, just for integrity. I also ripped out the bad mods on the ‘second’ amp. Famously, the wiring of Hiwatts is an engineer’s dream and these amps typify the attention to detail with which Hiwatt did things. Everything looks so precise. Everything looks just so tidy. Compared to a Marshall, a Fender or even a Mesa Boogie, these things are just beautiful inside. This kind of precision arrangement surely contributed towards the well-known, superior signal-to-noise ratio associated with those old Hiwatt amps. Remains of several shark-fin guitars were also found with the amps and in other chambers, prompting expedition artist Tony Burlinson to knock up an impression showing Pharaoh Rokatiti doing his thing in the desert. Archaeologists didn't find any evidence of a band and speculate that Rokatiti was a solo act. Perhaps he was ahead of his time. Perhaps like the nail, ancient Egyptians didn't conceive the idea of a rock band. Perhaps we'll never know... Anyway, once the chasses had been cleaned and I had checked the amps were safe, I moved on to the cabinets and spent several days getting the boxes to look like they might have, a couple of thousand years ago. While I was doing that, I ordered valves and capacitors from my good friend, Derek Rocco at Watford Valves. Derek has been supplying me with valves and caps for decades and I've had the privilege of seeing his digital test / calibration equipment in action. My customers expect the best, so I simply won't source these vital components from anywhere else. Co-designed by Marshall and the Shugaung factory in China, the EL34B is an evolution of the famous ‘Winged C’ EL34 which, by 2007, Svetlana was having problems supplying. Today the Shugaung EL34B is used by all the big valve amp manufacturers including Hiwatt. Here's what Derek Rocco says: "What I have found with the EL34B, is that in clean mode the valve remains cleaner at higher volume but when driven, it breaks up easily with plenty of rich harmonics." Replacing the valves was straight-forward enough but the large power supply capacitors were going to be a bit more challenging. It would have been easy enough to rip out the old caps and drop in the new ones but I wanted to retain that lovely Hiwatt wiring. Although roughly the same size, the terminals on the new capacitors were orientated differently and they had a different pitch, to the originals. The difference was enough to make things a bit tricky, even after I'd carefully disconnected the old caps. It took a while and a lot of patience and careful thought to the arrangement. In fact I treated the replacement of each of the five capacitors, as a separate operation... and of course after having done one amp, I had to do it all over again. As mentioned, amp 2 had three mods; one provided a feed off the speaker outputs which was poorly buffered. Another provided a feed off the master volume and the third, which had been partially disconnected, looked like a line input, bypassing the first couple of valve stages. Perhaps Rokatiti wanted to connect his amps somehow. Hmm... If that was the case, I would have expected to see similar mods on the other amp. Anyway, wanting to put these amps as close to factory as possible, I ripped all of them out . I'd run out of plastic 11mm hole plugs so I had a couple of frustrating days' wait until my reorder arrived in the post. One of the holes in the rear panel, had been drilled straight through the serial number plate and although the serial number itself was still quite legible, it just seems such a shame. I did try to contact Hiwatt asking if I could get a replacement serial number plate but disappointingly, I'm still waiting for a response. 🙁 After a couple of days, the job was done and I plugged in the first amp into my custom-built dummy load which has a feed that allows convenient connection to my oscilloscope. Power on... No big bang, just that gentle hum that we associate with valves amps. Wait a minute for the valves to warm up and then.. Standby, off... I set my signal generator to chuck out 1kHz at -20dBm and slowly wound up the input gain on the Normal channel. Then I inched up the master volume. Yes, that's right. The DR-103 was a master volume amp and was a little ahead of it's competitors. The oscilloscope displayed a perfect sinewave. Well that's a good start. I tested the amp at several frequencies allowing me to check the functionality of the tone controls. Wow! Very smooth, no drop-outs or sudden bursts. Okay, now I need to plug this into a cab and check it out with a guitar. I chose not to use a power soak and was prepared to crank this. Following the flood at my studio last August, I'm still working from home, so this all happened in my kitchen! Boy, is this thing loud! I was so taken back that I forgot all about the fact that the amp actually worked. I played for about half-an-hour, loving every second and everything remained solid. The second amp was next and performed exactly the same as the first. Amazing. After a couple of thousand years, these things still frigin' rock!!!! 🙂 "Hiwatt Amps Found In Pyramid" Well, not quite but it is April fools' day, LOL. 😀 For those interested, the serial numbers on Adrian's amps indicated that one was made in 1971 and the other in 1972. Although a challenge, restoring these Custom Hiwatt 100s has been a real pleasure. Showing their age but after a full refurb, they're actually in remarkably good condition and despite a couple of new fittings, are pretty original, too. More importantly, they just sound amazing! If you're lucky enough to have found a couple of Hiwatt amps in a pyramid, or perhaps at the back of your attic, please do contact me. I'd love to know about them! These Hiwatt DR-103 amplifiers are a unique link to a bygone age. I’m not talking about a time when thermionic valves ruled, or Pete Townsend of The Who or Dave Gilmour of Pink Floyd, were household names. I’m talking about a time when the likes of Jim Marshall and David Reeves (founder of Hiwatt Amplification), actually cared about their products, the craftsmen who made them and their customers. I was and always have been a Marshall man but the truth is Marshall, Hiwatt, Fender, it didn’t matter. As a budding rock star, owning one of these amps made you feel like you’d just joined an elite club and that stardom was now somehow, guaranteed. That big black box wasn't just an amp. It was a thing of magic. In fact, back in 1980, when I got my very first Marshall, it sat on my parents’ dining room table for a couple of days, with me err... just staring at it. I fondly recall the front cover of the Electric Warrior album by T. Rex which pictured a silhouette type image of Mark Bolan playing his famous Les Paul, in front of one of those old stacks. Oh wow! That image was just so inspiring and now I was the owner of a real Marshall amp and there was suddenly a connection between me and Mark Bolan. I felt like someone special and I just knew that all I needed to do now was to record that hit song. Well, none of that ever happened but I was definitely sold the dream! Indeed, the dream-maker package disappeared a long time ago. Digital processing, modelling and IR technology means that you can now dial up a patch to sound ‘like’ whatever or even whoever. Rock was the sound of anarchy and loud, overdriven, low-slung electric guitar, was the symbol of a non-conformist youth. I remember bunking off school to play guitar. Today kids go to school to learn to play rock. Seriously?!?!!? "Well now-a-days, it's all about the music." I hear people say. Hmm... I remember a time when it was (all) about a whole "lotta" love, I mean more... ... MCK-70 Memory Checker for the Roland MKS-7017 February 2021Introducing a fantastic utility, MCK-70 is a memory checker for the Roland MKS-70 and JX-10, developed by non-other than Guy Wilkinson. A few weeks ago, I received a Roland MKS-70 from a customer in Canada. He’d just had it upgraded with Guy Wilkinson’s fabulous VFD module and Fred Vecoven’s PWM mod but then weird things started to happen. This machine was then sent a couple of thousand miles across the Atlantic to see what I could do with it. The first thing was to fix the power supply. It was totally shot. Signs of heat damage and all regulated outputs showing zero volts except the -15V line which was reading -21.5V, wasn’t a good start. Oh dear. Anyway, I got that going temporarily as the customer agreed to have Guy Wilkinson’s P0004 switched-mode power supply installed. The next issue was that some voices weren’t playing. After going over the voice-boards and confirming that they were both okay, I decided to look at the assigner (CPU) board. To keep things simple, I disconnected the Vecoven PWM mod and I also installed the original Roland firmware. This meant that I had to have the voice-boards connected which is a bit of a pain. After a lot of testing, chatting with Fred Vecoven and Guy Wilkinson, it seemed clear that the machine had a memory issue. Guy told me that he’d developed a little bit of software to test the RAM in the Super-JX and we agreed that this would be a perfect opportunity to actually check it out. Guy e-mailed me the bin file, I promptly burnt a ROM, installed it into the MKS-70’s Assigner-board and switched on. Oh wow! This is so cool! Running in the processor's on-board memory and thereby leaving all other memory free, MCK-70 systematically checks not only the main RAM but also the gate-array RAM, writing all zeros as it sweeps. After a few seconds, you end up with an ultra-clean slate, a Super-JX that's cleaner than factory! I then loaded some factory stuff into the MKS-70. Wow! All looking good so far. Programming a very simple tone and patch confirmed that everything was working and that the issues that were present before, were all gone. Guy, you’re a genius! THANK YOU, my friend. 🙂 It was obvious that MCK-70 would be really useful to others and so Guy and I decided to make MCK-70 Memory Checker for the Roland MKS-70 and JX-10, available to purchase in my on-line store. A great tool for anyone who may have similar MKS-70 or indeed JX-10 memory corruption problems, MCK-70 will save you a lot of hassle and money. Removing the TC5564 RAM chip requires removal of the assigner-board and unlike the voice-boards, the assigner-board has a couple of delicate membrane cables connecting it to the display board and the cartridge board. You really want to avoid disturbing these, if you can. On top of that, the TC5564PL-15 isn’t at all easy to get hold of and hey, why on earth would you want to change the RAM chip in your Super-JX if you could know that all that’s happened, is that the memory’s got a little… well, bent? IMPORTANT When purchasing, you can select your preferred format; a downloadable .bin file or a physical ROM. If you buy the former, you'll need a ROM burner to put the program on to a 27C256 ROM. If you buy the physical ROM version, that'll be sent out to you. This will totally delete the memory in your machine. Don't mess with it unless you actually have an issue or your machine's memory is backed up. Although I've used a real case study involving a customer's MKS-70, MCK-70 will work in the Roland JX-10!... Cheetah MS6 Power Supply27 January 2021Just before Christmas 2020, I got sent a SoundLab SST-19 guitar pre-amp and a Cheetah MS6 synth module. Both needed power supplies. The SST-19 was immaculate and the customer was confident that it was working (when it had a power supply, of course). You can read all about that here soon. The MS6 however, was a different story all together. The customer told me that one day it just went bang. In fact, it tripped the electricity supply to his house! After a brief conversation via e-mails, he sent me his machine requesting a complete Cheetah MS6 power supply build. Again, I was told that the machine was working prior to the bang but of course I had no idea if the unit had been damaged by the fault. It was a gamble and there weren't too many resources available on this thing, either. Here’s a list of useful stuff that I did find: http://www.vintagesynth.com/misc/ms6.php http://www.maad.net/ms6/ http://www.butoba.net/homepage/ms6.html Readable schematics were also thin on the ground and when I did find a copy that was readable, that’s all it was, a schematic with very little useful reference. SIDE NOTE To speed things up in the long run, I spent a couple of hours cleaning up and organising the best schematics I could find. My small contribution to the the Cheetah MS6 community and hoping this will be useful to someone, organised and readable schematics can be downloaded here. 🙂 So, where were we? Oh yes... The unit turned up and I took off the lid. Ah! So, someone’s been in here before. Three of the four regulators had been replaced. They’d been attached to a thin aluminium strip which had then been glued to the inside of the case and I'm sorry but the soldering was atrocious! After taking the board out, it was obvious that this box had sustained fluid damage at some point in its life. Hmm… looked like I had my work cut out. Oh and the original firmware had been swapped out for the Maad KM 3.0 custom version. Sceptical at first, after some research, I have to confess that I've only heard good things about this. 🙂 Anyone who’s familiar with the Cheetah MS6 will be aware that the power supply is well, bloody awful. It’s not uncommon for example, for the case to go positive. Yes, you read correctly. The transformers (yes, there two) apart from being underrated are quite unreliable and the original heatsinking is totally inadequate. My initial approach to the project was to build an external box which would house two uprated transformers and then provide a suitable connection from the box to the MS6. The latter part would require a hole or two to be drilled into the rear case of the MS6. There are four regulators supplying +/-5V and +/-12V. The backend was such that I could remove the original transformers and drop connections to the main PCB where the secondaries of those transformers come on to the board. Since the supplies were complimentary, each utilised a centre-tap. I found a suitable enclosure all-be-it, a little larger than I initially had in mind and began plans for the metalwork company. While that was going on, I cleaned up the PCB, getting rid of as much sign of the fluid damage as I could. Next was the post transformer part of the power supply which as I’ve already mentioned, was a real mess. The PCB seemed quite fragile around the rectifier diodes, capacitors, etc so I had to be careful. While I was in design mode, I knocked up a drawing for a proper heatsink. Well, I took the stripped-out case, the enclosure for the external power supply and my drawings to Lenton Engineering in Watford and a couple of weeks later, I got the call informing me that everything was ready to collect. The transformers, switches and connectors all fitted into my external enclosure, perfectly so if nothing else, I would end up with a groovy dual-voltage AC power supply. 🙂 The heatsink also fitted perfectly. This was a particular relief as the distance between the mounting holes on the heatsinks of the regulators didn’t seem particularly uniform and I kind of had to compromise (not my usual style). I’d already made the cable that would connect the external box to the MS6 so all that was left to do was to drop in the actual connector and then wire it to the main PCB. So, all was done pretty quickly and it was test time. As usual, I cleared a big space, just in case it all went bang... again. Well, it didn’t. In fact, nothing happened at all for a few seconds. While the unit was still on, I quickly measured voltages and all looked good; +/-5V and +/-12V. Then characters appeared in the display but not as expected. All that was shown was ‘FE’ which was flashing and every now-and-then, some random stuff. I had read on-line that this could be an initial boot routine. Indeed, there was no voltage on the memory back-up battery. The other issue was that the buttons on the front-panel were totally unresponsive. After sometime, I noticed that one of the multiplexers was seriously hot, so I switched off. I replaced the CD74AC138E and tried again. Wow! It all fired up! It still seemed to go through some kind of initialisation sequence after displaying 'FE' again but this time, only for a couple of seconds. I hooked up a MIDI keyboard and attached the output to my mixer. Hey, I’ve got sound, too. More than that, all the voices were working. This was all quite relief. While I had the opportunity, I decided to implement my Live Forever battery mod. This required a slight modification to the battery back-up circuitry as the original battery was a rechargeable Ni-MH. I was dropping in a lithium battery which I really didn’t want the MS6 to charge when it was in use! Once that was done, I tried again. You know what? This thing doesn’t sound too bad. Of course there's better but you have to bear in mind the price bracket that this was in when it first came out. The power supply in these machines is notoriously bad. In fact, I’ll go so far as to say “it’s not a matter of if but when”. On top of that and as has been proved by the customer of this unit, they don't need to fail 'quietly'. This is a real shame as the synth is actually really quite good with six analogue voices and even multitimbrality. It’s also a shame that the MS6 has an old-style Ni-MH battery. If not charged regularly, there’s a significant chance of this leaking… all over your main PCB! So, if you have a Cheetah MS6 that you love dearly, please don’t hesitate to contact me regarding an external power supply, my Live Forever memory back-up battery mod In my humble opinion, I think it's worth it but please do something before it blows up... and trips your house electrics!... Marshall JMP-1 Knobs Nuts and Bezels21 January 2021At the moment I have three of my favourite MIDI valve pre-amps in for service and two of the customers have asked if I offer replacements for Marshall JMP-1 knobs, nuts and bezels. Well too be honest, it wasn't easy. You see the knobs although cosmetically the same, have different shaft fittings. The volume pot knob for example fits a 6mm spline shaft and the data encoder knob fits a ¼-inch D-shaft. Trying to find a knob that has the same diameter as the original, preferably a similar height and colour-wise would look good on the front panel of a JMP-1 is a tall order. Of course if that knob isn't available in versions that fit the two types of shaft, it's useless. Anyway, I persevered and came up to a couple of options. Having said that, one of them needs to be modified so as to fit the data encoder shaft. The PERFORMACE knob set looks very similar to the original and also has a similar rubber feel. It has a white position indicator instead of the grey line on the original. I personally think it's just easier to see. The STUDIO knob set is a little more posh and resembles knobs found on equipment like high-end mixing desks. It too has a white position indicator. Not as wide as that on the Performance knobs, the white position indicator on the Studio knobs, is a little more subtle. Made of hard plastic, it's got quite a different, clean feel when compared to the original. Unlike the Performance knobs, it's not a simple push-fit but requires securing via a recessed allen screw. Very posh, indeed! 🙂 In 1992, Marshall used a slightly non-standard input socket and headphone output socket on the front panel of the JMP-1. When I say 'non-standard', of course they're both ¼-inch but the threading at the front isn't quite the same as many other similar style ¼-inch jack sockets and so 'normal' nuts don't fit properly. How annoying! Again, I have managed to precure a bunch of these things. Available in two options, the first is a single high-quality moulding, in which the bezel is integral with the nut. Two of these are included in my Performance set. The second option has a separate bezel and nut. While the nut has a matt finish, the bezel is very slightly glossy. The combination looks pretty cool, in my humble opinion. These nuts and bezels are included in my Studio set. So if your JMP-1 is looking a bit sad 🙁 , please do check out my on-line store for my Performance and Studio replacement Marshall JMP-1 knobs, nuts and bezels. Update - 22nd January 2021 Wow! I've only just put up this post and I've already received e-mails from visitors asking why the top JMP-1 in the picture at the top of this post, is a different shade of gold, to the other two. Not a trick of the light, it is indeed much darker, perhaps a golden gold as opposed to a white gold. This unit is much older than the other two and I'm guessing that Marshall changed the company that did the plating on the facias, some time after the first few production runs. Pure speculation but what else can I say? Looks good, though!... Extend Memory Back-Up Battery Life21 January 2021My Live Forever back-up battery mod does more than just extend memory back-up battery life. It's not rocket science. It's not even particularly clever but an incredibly simple upgrade to many synthesisers, sound modules and effects processors, this upgrade offers the following advantages: Reduced risk of battery leakage. Reduced risk of damage to sensitive electronics as a result of battery leakage. Easier replacement of memory back-up battery. Easier measurement of memory back-up battery voltage. Higher capacity battery means that it'll probably outlive you! So just about all digital equipment has some sort of mechanism to provide memory retention. Your equipment has patches, right? So those patches are 'remembered' by your gear after power is removed, with the use of a memory back-up battery. Newer equipment doesn't always have a memory back-up battery. Instead, memory is held within what is known as non-volatile RAM. Anyway, older stuff does have a memory back-up battery and if left unchecked, the consequences can be devastating. I recently did a post on a gorgeous Sequential Circuits Prophet 5 Rev 2 that hadn't been touched for over thirty years. During that time, the back-up battery had degraded and had in fact leaked all over the CPU board. It's going to take me months to sort out the mess and that's going to be expensive! My Live Forever battery mod doesn't just involved replacing the original battery with a larger type. If possible, I try to mount the holder for the new battery, usually a lithium CR123, directly on to the chassis and off any PCB. In the event that the battery does leak, then it won't damage any circuitry. Of course mounting the new battery on to the chassis isn't always possible. The Marshall JMP-1 is a good example. There are two versions of the JMP-1. One has a case with a little room to allow for a CR123 battery holder to be mounted to the metal. The other and more popular version doesn't. In situations where the battery can't be mounted off-PCB, I simply have to find the best place to put it. MEMORY BACK-UP BATTERY TYPES Most vintage equipment that uses a memory back-up battery does so with something like a CR2030, CR2032 or similar type 'coin' battery that's soldered to a PCB and located close to the RAM (memory chip). This isn't always the case, though. The Roland MKS-80 for example, used a CR-1/3N battery as pictured below. My Live Forever battery mod involves replacing the original battery with a much higher capacity CR123 type cell which is also small enough to fit into many situations. The default battery chemistry is lithium or rather lithium manganese dioxide (LiMnO2). They're cheap, readily available and very reliable. Lithium CR123s however, aren't the only option that can be used for replacing the original memory back-up battery. While sticking with the CR123 form-factor, I'm a big fan of Lithium thionyl chloride batteries (LiSOCl2), for example. Designed specifically for very low-current, very long-life applications, they're ideal for the job. They are however, more expensive and more difficult to procure. Finally, a long time ago, I experimented with clip-on retainers that fit over the CR123 battery holder, thereby offering more physical security to the actual battery. Well, apart from having installed my Live Forever battery mod into countless machines over the years, all of my own gear is fitted with my mod. In over thirty years, I have NEVER experienced a battery being dislodged from the battery holder and feel that any impact that would be strong enough to do that, would most likely seriously damage the machine that it's fitted to! The main reason I don't supply the retention clip however, is that they have a very (VERY) tight fit. I'm concerned that if the battery ever does need to be removed, damage to the unit may occur while simply trying to remove the clip! 🙁 Anyway, my Live Forever memory back-up battery mod is available for just about any synthesiser, sound module or effects processor so don't hesitate to contact me if you have any questions. Don't forget, it does more than just extend the memory back-up battery life in your favourite vintage gear. It'll give you peace of mind too! In the meantime, if you'd like to learn more about lithium manganese dioxide and Lithium thionyl chloride batteries, please check out these links: https://en.wikipedia.org/wiki/List_of_battery_sizes#Lithium_cells https://www.geeksforgeeks.org/difference-between-volatile-memory-and-non-volatile-memory/ http://www.tadiranbat.com/compare-lithium-cells.html... Eclipse Marshall JMP-1 Skipping Data Encoder Fix21 January 2021I regularly receive Marshall JMP-1s for service and customers often complain about the skipping or jumping of the data entry control. Cleaning (yeah, right) or even replacing the data encoder, doesn’t always resolve the problem. Hence, I designed the Eclipse Marshall JMP-1 skipping data encoder fix. Unlike a potentiometer which comprises a wiper that's in constant contact with a resistive track, a data encoder is basically a series of switch contacts with the wiper moving from one contact to the other, as the encoder is turned. As you may have guessed, this means that there’s a gap between each switch contact (correct) and as the wiper moves, there’s a region of zero contact between the wiper and any switch contact. When the wiper leaves or comes on to a switch contact, the electrical signal can be quite transient and messy, similar to an electrical mains spike that sometimes occurs when switching lights on and off but obviously not as big. This is called contact bounce and if the data from the encoder is going directly into a processor, then it should come as no surprise that the processor just wouldn’t know what to make of it. All it wants to see is noughts and ones at nice regular intervals (a pulse). Modern data encoders are optical and so there's no physical contact between a wiper and a track and hence, no bouncing. To overcome the problem of bounce on mechanical data encoders, a bounce eliminator (or bounce filter, as it's sometimes referred to) is required to remove the spike, thereby making the signal look more like the regular pulse it's supposed to. What the processor wants to see is kind of ‘underneath’ the spike. For some crazy reason, Marshall, didn’t incorporate a hardware debounce circuit in the design of the JMP-1. Debouncing can be done in software but generally, designers aren’t keen on this approach. I have no idea if the firmware of the JMP-1 includes debouncing suffice to say that if it does, then it doesn’t work! A hardware solution is always preferred. One hardware approach is to use passive filters, a combination of resistors and capacitors but due to the unpredictable nature of bounce, this approach can also be unreliable and so Eclipse uses the preferred third option which is to delay the reading of the signals coming off the encoder, thereby missing the bounce. This is achieved using what are called Schmitt triggers. Fundamentally, Eclipse Marshall JMP-1 skipping data encoder fix, is an active bounce eliminator which can be easily fitted between the JMP-1's data encoder and the main PCB and hence, the inputs to the 8031 processor. The data encoder in the JMP-1 is attached to the motherboard via a 3-way Molex connector. Unplugging this connector and plugging it into Eclipse and then plugging Eclipse into the socket where the encoder was originally connected, only leaves one wire to be soldered to a filtered +5V supply point and you're done! You don't have to remove the main board and as mentioned, there's only one solder point to make. Unless you intend to change the rotary data encoder at the same time, you don't even have to remove the front panel. Simple, eh?!? 🙂 I always seem to have a couple of JMP-1s in for service but just before Christmas 2020, I had one that was of particular interest. The customer mentioned that amongst other things, the data entry control on his JMP-1 was skipping, making it difficult to manually select patches and change parameters. I told him that finding a suitable replacement isn't easy and it sometimes doesn't fix the problem anyway, as the problem isn't actually the encoder but the lack of filtering between the encoder and the processor. Stuart volunteered his JMP-1 to be the guinea pig for Eclipse. I wanted Eclipse to be easily installable by anyone with a little technical competence but I also wanted it to be as small as possible. In fact Eclipse was originally designed using surface mount devices (SMD) but the build-time was ridiculously long making it just too expensive. With a little ingenuity however, I was able to get full-size components on to the original board size! So with Eclipse measuring only 37mm x 24mm and weighing just a few grams, I could use self-adhesive nylon PCB spacers, allowing for end-user easy mounting close to where the data encoder connects to the main PCB. The prototype Eclipse was soak tested in Stuart's JMP-1 all over Christmas 2020 as I put it through its paces, suffice to say, that it all worked like a charm! I'm really happy with this little upgrade. "Simple but brilliant, Mr. Bond". Eclipse actually worked better than I intended as it . doesn't just solve the data knob skipping problem. It makes the whole thing feel smooth, responsive and accurate, how it should have been in 1992! Although not as open as a potentiometer, the data encoder isn't hermetically sealed meaning that contaminants can get inside the encoder casing. The ingress of dust and dirt and more importantly, years of wear, won't do you any favours when it comes to skipping and like all electronic components, these data encoders have a limited shelf-life. THE BAD NEWS The data encoder that Marshall used in the JMP-1 was discontinued by Bourns, the manufacturer, in 2012 due to the lack of RoHS compliancy and is really difficult to find, now. Bourns did release a RoHS compliant version and I'm not sure why even this is hard to track down. THE GOOD NEWS Sometime ago, I did manage to find a bunch of original data encoders as used in the JMP-1 and while I try to source an equivalent part, I'm making Eclipse available with the option to buy a replacement encoder. I strongly suggest that you snap one up while I still have some. I have pre-wired the data encoders with a 3-way Molex connector so that you don't have to fuff around taking the wires off the original encoder and attaching them to the new one. My wired connections are a little longer than the original, thereby giving you a bit more leeway when it comes to the placement of Eclipse. MASSIVE TIP If your data encoder isn't too bad, if it's just started skipping or jumping, please still consider buying Eclipse WITH a replacement data encoder! Just fit the Eclipse board and keep the data encoder that you bought with Eclipse, in the supplied ESD bag, somewhere safe. As I've already said, these things have a limited shelf-life so it will wear. Even if your JMP-1 is in a super clean environment, the contacts will degrade. Eclipse will help reduce the effects of wear of your encoder but a point will be reached when it's just going to have to be replaced. These data encoders are getting increasingly more difficult to procure but hey, now you've got a spare! 🙂 Each Eclipse is hand built by me and fully tested on... you guessed it, a Marshall JMP-1, before it gets sent out. If you're getting really frustrated because your data entry knob is skipping and if you have a little technical competence, then the Eclipse Marshall JMP-1 skipping data encoder fix, should be of interest to you. Please don’t hesitate to contact me to learn more or alternatively, you can just... There's not too much out there resource-wise about the JMP-1 but these links might be of interest: http://www.waxer.nl/index.php/2015/12/marshall-jmp-1-preamp/ https://www.facebook.com/themarshalljmp1 UPDATE - 7th May 2021 It's coming up to three months (where has the time gone) since I launched Eclipse and I just want to say a big THANK YOU to all those who have bought it and specifically for all the very kind-worded e-mails that I've received. Designing a product to resolve an issue on a vintage piece of equipment is a challenge. For a start, the market you are aiming for, is constantly shrinking as there are of course, no more JMP-1s being made. So, you're not doing it for the money, right? In fact the reasons you do it are because you love what you do and have empathy for owners of the equipment. Once designed and once tested, you then have to get an installation manual together and again, THANK YOU so much for all the compliments I've received regarding that bit of hard work. I'm so glad that everyone has found the installation manual comprehensive and easy to follow, making Eclipse a breeze to install. 🙂 Here's a heads-up, everyone; I have two more products coming out for the Marshall JMP-1, some time over the next few weeks, so stay tuned!!!! HINT: If you have a dead Marshall JMP-1 with a blown transformer, DO NOT THROW IT AWAY. 😀 I'm deeply concerned about the environment and the exploitation of labour and so I always use local manufacturers in preference to the Far East, with the following in mind: I can be confident that workers are treated fairly and earn a proper wage. I can be confident of the standard of quality of each item that is delivered to me. Communication is important and using local manufacturers, all correspondence is quick and understandable. I believe in supporting the local economy. I can be confident that the disposal of manufacturing waste is managed properly and in accordance with national and EU law. Using local manufacturers isn’t the cheapest option but the above points are important to me. I hope that they’re important to you too.... Super Nova Power Supply for the Roland Juno-1061 January 2021 Following on from last summer’s Aurora project (read more about that here), I thought I’d have another look inside one of my favourite keyboard synths and see if I could do something similar. Well, it took me about a week to design the basics of what was very quickly to become the Super Nova switched-mode power supply for the Roland Juno-106. Being a guitarist, my selection of keyboard synthesisers is quite modest but I consistently find it amusing that many musicians walking into my studio, inevitably make a bee-line for my humble Juno-106. I have always loved this machine! It’s just so easy to ‘draw’ a sound using the top-panel controls and it always delivers. Lush, phase coherent and warm with no mistaking that classic Roland chorus, the Juno-106 has played a big part in my own musical history. Intended as a budget synthesiser, the Juno-106 was released in 1984, the same year as the MKS-80 and the JX-8P. It’s lack of velocity sensitivity and simple voice architecture didn’t seem to inhibit this monster-sounding machine’s popularity. Indeed, the Juno-106 is probably one of the best-selling synthesisers of all time. Today many named artists still use this fab synth and variations like the Juno-106S and HS-60 (or Synth Plus 60) both with built-in speakers, still sit in many a lounge or music room. After more than three decades however, time is taking its toll. Many will be familiar with the failing 80017A VCA / VCO devices, for example. Fortunately, Analogue Renaissance offers a replacement, the AR80017A. My Juno-106 is doing alright at the moment so I haven’t had the opportunity to try these yet. Having said that, I’ve only heard good things about the AR chips and I salute Jeroen Allaert of Cask Strength Electronics for such excellent work. On top of that, they look really, really cool! KiwiTechnics has always been a name you can trust when it comes to synth repairs and upgrades and after a couple of years in development, the guys recently launched a seriously powerful hardware / firmware combination for the Juno-106. Known as the Kiwi-106, this is a significant upgrade offering a huge array of fantastic and modern features that well, change everything! In fact one of the reasons Super Nova is red is to match the Kiwi-106 so I strongly suggest that you check out kiwitechnics.com to find out more! All these people doing this great stuff for the Roland Juno-106 and I couldn’t find anyone making a replacement power supply. Perhaps it's because we all know that Roland power supplies are really quite robust and have stood the test of time. An interesting feature and unlike many synthesisers of that era, the transformer in the Juno-106 is multi-tapped meaning that by moving a wire from one post to another (and changing the fuse), you can use the synth on virtually any domestic voltage supply across the world. The thing is, power supplies do fail. If the transformer packs up for example or starts humming, then that’s it. That’s why I designed Super Nova. Not just a replacement power supply, Super Nova is a modern, switched-mode power supply for the Roland Juno-106, meaning that for a start, it generates considerably less heat than the original linear power supply. There’s NO mains hum either and since Super Nova's filters are based on my good friend, Guy Wilkinson's design, Super Nova is also super quiet. And of course, being a switched-mode design, you can still plug your Juno-106 into any electricity supply around the world but this time... without having to open it up and change the transformer tap! Individually coloured LEDs for each supply including the 5V reference voltage, means that you can very quickly check line status with a glance. If you really want to know what's going on, conveniently located test points make measurements a breeze. The 5V reference voltage is set when each Super Nova is made, using regularly calibrated test equipment. A multi-turn pre-set however, allows for fine adjustment which may be necessary after several years, due to component value drift. One of my most popular upgrades to many machines I receive from customers, is my Live Forever battery mod’ and so like Aurora, Super Nova includes a provision to replace the memory back-up battery in the Juno-106 and take it off the CPU board. This has several advantages: A much larger back-up battery can be installed meaning that you probably won’t have to change it in your lifetime! In the unlikely event that the battery leaks, your precious CPU board is safe and won’t be damaged by battery fluids. Battery voltage can be easily checked without fuffing around with the CPU board. Just in case you do have to change the battery, it’s so much easier and doesn't require any soldering. The battery connects directly to the original battery points on the CPU board so all components associated with the back-up battery continue to function as as normal. Like several synthesisers of its day, the Roland Juno-106 is built on a plywood base. Heavy items like the keyboard assembly and power transformer, are attached to the base using machine-type screws that secure into corresponding steel lugs which are sunk into the plywood. The much lighter PCBs however, simply use wood screws to secure them (via spacers) to the wooden base. When you consider that the plywood base in less than 10mm thick, that sounds a little risky. On the other hand, there's no history of 'stuff' coming lose! I wanted Super Nova to be super secure so although the PCB could have actually been smaller, I chose to extend it, thereby taking advantage of the otherwise redundant M4 lugs that were previously used to hold down the transformer. Mounted on an aluminium plate, both PCB and plate are very securely anchored to the base of the Juno-106. The plate is further held in place with four wood screws. Super Nova fits perfectly into the Juno-106 and is relatively easy to install by anyone with some technical competence. It's very efficient, can be plugged into just about any power outlet in the world and has on-board Live-Forever battery mod. UPDATE - 6th January 2021 Super Nova has now been fully tested and me and my Juno-106 are lovin' it! I've completed detailed and fully illustrated, step-by-step installation instructions so, if you have a Roland Juno-106 with a bad power supply and are considering a replacement or if you have any questions, please just contact me. Or you could just... I'm deeply concerned about the environment and the exploitation of labour and so I always use local manufacturers in preference to the Far East, with the following in mind: I can be confident that workers are treated fairly and earn a proper wage. I can be confident of the standard of quality of each item that is delivered to me. Communication is important and using local manufacturers, all correspondence is quick and understandable. I believe in supporting the local economy. I can be confident that the disposal of manufacturing waste is managed properly and in accordance with national and EU law. Super Nova was designed by me and every Super Nova is hand-built and tested by me, here in Hemel Hempstead, Hertfordshire. The aluminium mounting plate is made by Lenton Engineering which is based just up the road in Watford and the printed circuit boards are manufactured by Minnitron Limited in Ramsgate, Kent. At the heart of Super Nova are four high-performance Vigortronix AC / DC converters which are made in Witney, Oxfordshire. Using local manufacturers isn’t always the cheapest option but the above points are important to me. I hope that they’re important to you too.... Marshall JMP-1 Needs Attention24 December 2020I’ve seen a few Marshall JMP-1s in my time and as some will know, I really do like this simple and straight-forward MIDI valve pre-amp. As such, I love working on them and enjoy testing the results even more! Having a Marshall JMP-1 in that needs a little attention is never tiring. Anyway, last week a customer who had just bought one of these off eBay, took the initiative and sent it to me for a full service. Although dated 1992 making it an original production example, you just wouldn’t guess it from the condition of the unit, it’s pristine. What a find! Stuart said that he’d like the valves checked as well as the back-up battery. He also commented that the data encoder was skipping. This latter issue is quite common. Marshall didn’t incorporate a hardware bounce eliminator into the JMP-1 and the outputs of the encoder, go straight into the processor. I therefore, took this opportunity to design something that would sort this problem out once and for all. In fact, Stuart's JMP-1 became the first unit to have my 'Eclipse' bounce eliminator for the Marshall JMP-1 data encoder installed and you can read all about that here. The valves were original and electronically, they will probably last another thirty years. Without modification, we know that the valves don’t really contribute too much to the tone of the JMP-1 but on this occasion, I decided to change them anyway, just so that everything’s nice and clean and so I dropped in a pair of cryogenically treated premium valves sourced from my good friend Derek at Watford Valves. The most disturbing observation when I took the lid off, was the back-up battery. It was obviously swollen and although still backing up the memory, was in desperate need of changing. This point is of particular importance. I leaking battery could render your JMP-1 useless! Please do check out my post of Battery Acid Damage. I explained my Live Forever memory back-up battery mod’ to Stuart and he loved the idea so we went ahead with that. I cleaned the volume pot on the front as well as the sockets which although looked okay, hadn’t been touched for almost thirty years. Since the unit had just been bought, there were no user patches of significance so I initialised the memory. If you need to initialise your unit, follow my guide here. I put the lid back on, plugged it in and WOW! This machine looks, feels and sounds like it was made last week. FANTASTIC!!!! People love their Marshall JMP-1s and I often get asked to supply more than a service. As an example, I recently had a JMP-1 in, that had a data encoder knob which looked like it had spent half-an-hour in boiling water! The rest of the unit was pristine. Of course, being discontinued for well over twenty years, Marshall don’t really hold a lot of spares for the JMP-1 and sourcing alternatives isn’t easy. There are two knobs on the front panel and although they look the same, the fittings are quite different. The knob for the volume pot has a 6mm spline shaft and the knob for the data encoder has a ¼” D-shaft. Finding a knob with the correct base diameter, height, ergonomics and colour is hard enough. To find a knob that satisfies all of that and is available in two versions, one with a 6mm spline shaft fitting and another with a ¼” D-shaft fitting is well, kinda impossible. So, while my hunt continues, I am forced to improvise. Having said that, customers seem well chuffed with the results. The other items which often get lost or damaged, are the black nuts on the front input and headphone jacks. Well you’ll be pleased to know that I have managed to track down this rare beast including the black bezel for these particular jacks. Check out my post on replacement Marshall JMP-1 Knobs Nuts and Bezels to learn more or just visit my store to buy. As mentioned, I don’t tire of working on these machines, so if you’ve got a Marshall JMP-1 that you feel could benefit from some attention, just contact me.... Battery Acid Damage16 December 2020This week I've had two machines come in; a Marshall JMP-1 and a Sequential Circuits Prophet 5 (yes, you read correctly). One was just in time and prior to battery leakage. Unfortunately the other arrived too late and had suffered considerable battery acid damage. Last week I received a call from someone who had just bought a Marshall JMP-1 and, after stumbling across my article on Marshall JMP-1 Service while doing a little research on-line, decided to send me his new purchase for a once-over. I got a shock, when I opened it as the battery was right on the point of popping. This was incredibly lucky. With a date of manufacture of 1992, the battery was the original, as fitted in Marshall factory, twenty-eight years ago! After quickly removing the battery, I tried to take some macro pictures to show swelling. If you look closely, you might be able to see what I'm talking about. The top of the battery should be flat. I analogise battery check-up with home security; most of us consider investing in CCTV or an alarm system after an incident! Stuart took the initiative and sent me his JMP-1 shortly after he bought it. Unfortunately the owner of the Sequential Circuits Prophet 5 wasn't so lucky. Apparently this machine had been stored in a case since it was used with Roxy Music over thirty years ago. It's incredibly sad to see horrendous battery acid damage on the inside of such a beautiful example of this legendary machine. Many components and quite a bit of PCB tracking are damaged but I'm going to try my best to fix this. Having said that, I've already informed the customer that things aren't looking good. So, I urge anyone who's buying vintage gear to get the memory back-up battery checked. I also strongly advise all, to regularly check the memory back-up battery in your equipment. Battery acid damage is a terrible thing and can cost a fortune to put right, if at all even possible. My Live Forever battery mod which is available for most synthesisers, keyboards, effects processors, etc, doesn't just replace the factory fitted battery with something more substantial but if possible, I also move the battery off the main PCB. Aurora (for the Roland MKS-80) and Super Nova (for the Roland Juno-106), are a couple of switched-mode power supplies that I make and that are either available ready assembled or can be installed by me. I recently released Aurora Board Bx, an option that includes a remote memory back-battery and Super Nova was designed with fully integrated remote memory back-battery facility. I'm currently designing power supplies for several other machines and I'm including the same remote memory back-up battery facility on all of them. A WORD OF REASSURANCE Back-up batteries aren't just wired to memory chips. There's always associated circuitry which depending on the age of the machine, the manufacturer and so on, can do several jobs such as switch between battery and PSU power when the unit is switched on and off, provide current limiting and reverse polarity protection. Since my Live Forever battery mod connects directly to the original back-up battery connection points, any components or circuitry associated with the memory back-up function remain untouched and fully active. As far as your machine's concerned, nothing's changed!... Firmware Update Service7 December 2020I've had my old serial EPROM programmer for years, well... decades and last week, I bit the bullet and replaced it with something a little newer. Instead of having to hunt down old 'windowed' EPROMs, I can now offer a firmware update service providing the latest devices. I don't often get asked for firmware but when I do, I'm usually able to oblige as over the years, I've built up a small repository of firmwares for various machines. 99% of the time, I'll use EEPROMs (electrically erasable programable read only memory) for my firmware update service. These devices don't have the window associated with older EPROMs and don't need exposure to ultra-violet light, to be erased. They're also considerably cheaper and from a programmer's point of view, a lot more reliable. I guess the hard part for end-users, is identifying the firmware version inside their machines. Some machines display the version when they boot but many don't and the only way to find out, is to open up the box! I understand that can be a bit daunting for some, so for a small fee, I'm happy to do that for you, if you can get to me. If you want to try this yourself, then you're looking for a chip which which will be in a socket. It may have the firmware version just written on a label that's stuck on top of the chip and covering a little window. Some companies Roland used a coded label as shown below right. The EPROM label on the left shows the date (4th November 1987), followed by a 'M' which I'm guessing to be the actual version. The EPROM on the right is on the voice-board of a Roland MKS-80 Rev 4 and the label indicates that the firmware version is 1.1. Both images show older devices which have windows under the labels through which exposure to ultra-violet light is used to erase the device. So don't peel the label off! To take advantage of my firmware update service, please just message me with your requirements and I'll see what I can do.... New Aurora Board Bx2 December 2020Over the past few of months, I've installed several Aurora systems into customers' MKS-80s and my Live Forever battery mod gets asked for a lot so that got me thinking... The layout of the Aurora Board B which hosts mains protection and filtering, has been tweaked so as to allow for a couple of additional components. The new Aurora Board Bx now has a CR123 / CR123a battery holder and SMD pads which, after removing the original CR-1/3N memory back-up battery, can be connected to the battery points on your MKS-80's CPU board. As with the original Aurora Board B, the new Aurora Board Bx sits on a steel plate just like the one that supported the original MKS-80 transformer, making upgrading easy. With a capacity of 1.5 Ah, a CR123a will last almost nine times longer than the original CR-1/3N. The battery voltage can be easily checked without having to lift the MKS-80's two voice boards (oh boy). On top of those benefits, if (seriously, if) the battery ever leaked, your precious CPU board will be well out of harms way. Since the enhanced back-up battery mod connects directly to the points on the CPU board where the original battery was, there are no other components to add and circuitry around the original battery remains untouched. There is for example, a protection diode that's in series between the battery and pin 24 of IC5 (memory). This is not bypassed and remains totally functional. IMPORTANT Don't forget to back up your MKS-80's memory before disconnecting the back-up battery. Switch off AND unplug your MKS-80 from the mains, whenever checking the battery voltage. Of course not everyone will want to take advantage of the enhanced back-up battery option that the new Aurora Bx board has to offer. That's why the original Aurora Board B will still be available. Check out my store or contact me for further information. Here's the official Aurora post and here's a post detailing the development of Aurora. Oh just one more thing; batteries are NOT included! I've always wanted to put that somewhere. 🙂 No seriously, shipping stuff with batteries is a little difficult. Our postal service really doesn't like it. UPDATE - 24th December 2020 Aurora installation instructions are now available in German. Die Installationsanleitung für Aurora und Aurora Board Bx ist jetzt in deutscher Sprache verfügbar. UPDATE - 24th April 2021 Aurora is now offered with the optional V06 data cartridge re-enforcement bracket. Such a cool solution to a problem that many Roland MKS-80 owners will be familiar with, the V06 basically strengthens an undamaged cartridge slot and reinforces a broken one by putting 2mm of solid steel behind it! Existing Aurora customers take note; once your Roland MKS-80 is open, V06 can be installed in a few minutes, with just a M3 (5.5mm) nut-runner. Read more about the V06 here. I'm deeply concerned about the environment and the exploitation of labour and so I always use local manufacturers in preference to the Far East, with the following in mind: I can be confident that workers are treated fairly and earn a proper wage. I can be confident of the standard of quality of each item that is delivered to me. Communication is important and using local manufacturers, all correspondence is quick and understandable. I believe in supporting the local economy. I can be confident that the disposal of manufacturing waste is managed properly and in accordance with national and EU law. Using local manufacturers isn’t the cheapest option but the above points are important to me. I hope that they’re important to you too.... Chorus chip Transplant26 November 2020After thirty-something years, many instruments that use the famous Panasonic designed MN3007 or MN3009 bucket brigade delay lines are now displaying symptoms of noise and it may be time to consider a chorus chip transplant. Initially, the sound when passing through the chorus, seems to contain artefacts. As the degradation of the substrate worsens, the chorus becomes increasingly noisy and can even have a kind of crunch to it (distortion). Do not however, confuse noise generated within the chip with LFO leakage into the audio path. This is quite different and can usually be tuned out via pre-set potentiometers in processors like the SBF-325. Fortunately the MN3007 is still available and Xvive has released a design of the MN3009 which I think sounds amazing. Here's a list of some Roland instruments, processors and amps and the chorus chips that they contain: SDD-320 Dimension-D (2 x MN3007) SBF-325 (2 x MN3007) MKS-10 (2 x MN3007) MKS-20 (2 x MN3007) JC series guitar amps, like the JC-120 (1 x MN3007) VP-330 (2 x MN3009) SA-0 (2 x MN3009) Juno-6 (2 x MN3009) Juno-60 (2 x MN3009) Juno-106 (2 x MN3009) Juno-106s (2 x MN3009) HS-60 (2 x MN3009) Alpha Juno 1 (2 x MN3009) Alpha Juno 2 (2 x MN3009) JX-3P (2 x MN3009) JX-8P (2 x MN3009) JX-10 (4 x MN3009) MKS-30 (2 x MN3009) MKS-50 (2 x MN3009) MKS-70 (4 x MN3009) I charge a standard £100 plus VAT (£120) to change the chips in all of the above machines with the exception of the Super-JX (JX-10 and MKS-70) which will cost £130 plus VAT (£156). High-quality turned-pin sockets are fitted before the chips are installed and the new replacement devices then simply plug into the sockets. This means that they can easily be removed without desoldering, anytime in the future, In my humble opinion, the new devices from Xvive sound very solid and not airy like the original chips. With definition and detail, you'll defiantly hear a substantial difference in your tone. If you'd like to book in your machine, please just contact me or check out the Chorus Chip Transplant item in my store.... Alesis MMT-8 Repair and Refurbishment19 November 2020My first stand-alone sequencer was the Alesis MMT-8, so when I recently got one of these in for a full repair and refurbishment, it brought back a lot of great memories. In the late eighties, I had a couple of Roland S-550 samplers. If you remember this machine, you might also remember the monochrome (green) screen, the mouse and the sequencer software. All quite superb but even back then, I didn't always want to 'boot up' my 'sequencer' S-550, just to get down an idea. Stand-alone sequencers at the time, like the Roland MC-500 for example, were quite expensive until that is, Alesis released the 'MIDI Multi-Track 8' or MMT-8. Small, easy to use, no fuff and above all, very cost-effective, the MMT-8 soon became a big hit and I find it's popularity today not just amusing but a testament to it's design. A quick look around Google reveals that many named artists, specifically DJs, are using this machine even today! Others soon tried to bite back and in 1990 for example, Roland brought out the MC-50 (shortly followed by the MC-50 Mk II). Although hugely powerful, machines like the MC-50 were still considerably more expensive than the humble MMT-8. In fact, the MC-50 was my second stand-alone sequencer and I recall not regretting hanging on to my humble MMT-8. Sure it's got a couple of drawbacks; limited memory (100 songs, 100 parts, 10,000 notes), external storage via MIDI or tape only (no on-board floppy disk drive) and a small 16 x 2 screen. The thing was, the MMT-8 was instantly familiar to many as it kind of felt like a multi-track recorder so once you accepted its limitations, you realised that you had a tight little sequencer which actually contributed to a healthy workflow. So this MMT-8 was definitely looking worse for wear and things just weren't working like they used to. In fact on power-up, although it came on, it was just all locked up. Seeing as it didn't have any knocks, dents or scratches though, the first thing to do was to completely take it apart and give the casing and the switch contact membrane, a good wash. At least it's going to look the business so if nothing else, I could turn this classic into a bit of modern art! 🙂 After several decades, even a well kept MMT-8 will suffer badly from intermittent and / or none functional keys. The problem is that while the switches on the back of the rubber contact membrane use small carbon-coated pads similar to those used in keyboards, the complimentary contact PCB just had metal track, like the track side of an old PCB. So the next thing to do was to make sure that this aspect of the machine was fixable. Well, having had one of these myself, you guessed it, of course I knew it was fixable! Cleaning and treating the switch contacts on both the contact membrane and the contact PCB, is well worth it, making an old MMT-8 respond like it did when it was taken out of its box for the very first time but... it's got to be done properly. The MMT-8's casing is plastic, which is now old plastic, the point being that it's become quite brittle. Hence, care should be taken when disassembling this box and removing the contact PCB in particular. It's not difficult to break the screw pillars and they really aren't easy to repair if at all. When reassembled, if the contact PCB is not tight to the contact membrane due to a missing or badly fitting screw, then you might have cleaned and treated the switch contacts but you'll have some play when depressing the switches and you'll kind of be back to square one. It's equally important when replacing the contact PCB that the screws are NOT overtightened. I then checked the battery which had years of capacity left on it. Next, the dreaded freeze. As previously mentioned, when you switch on, a bunch of LEDs light up, there's nothing on the screen and the machine is quite unresponsive. Let's try a factory reset first; hold down <ERASE>, <PAGE UP> and <PAGE DOWN> simultaneously, while powering up. Hmm... well that didn't fix anything. Probably cleared the memory, though. 🙁 This is actually a fairly well-known issue and one of several components that comprise the processor reset circuitry, is usually the problem so that's where I looked and low-and-behold... After ensuring that the contacts were good, both on the rubber contact membrane and the contact PCB, it would appear that I still had a couple of 'switching' issues. You'll notice on the first image at the top of this post, that track LEDs 4,5 and 6 are out. That's not because they're switched off. In fact the buttons actually work. It's the LEDs that aren't working. Also, a couple of other buttons were still faulty and not doing anything however hard I pressed. I quickly traced the problems back to U7 and U8; two HC754E 8-way flip-flops. It would appear that five flip-flops were stuck and not flipping or flopping! So now this MMT-8 looks like new and more importantly, it actually works like new! Well... not quite. One thing I remember about this machine was the questionable viewing angle of the display. The MMT-8 isn't a square or any other regularly shaped unit. It's all kinda slanted and just says "you need to be sitting down to program me". Well indeed, that's very true and after three decades, even sitting down, the LCD has become pretty unreadable with a low-level backlight and low contrast. Actually, the contrast and hence the viewing angle is adjustable, via a pre-set pot that's inside the machine (R67). In fact I have a theory as to why the viewing angle is so poor; when these units were inspected and set up at the factory, the technicians were probably err... sitting down! Hence, the contrast was adjusted accordingly. So my Alesis MMT-8 repair and refurbishment continued with hunting down a suitable LCD. I soon came across circuitbenders and bought the perfect module for this machine. The brightness, clarity and viewing angle of modern LCDs is obviously very different to those early devices from the eighties. Now we're done and will you take a look at that... A blast from the past in stunning, fully working condition. The Alesis MMT-8 has got to be one of the few machines with a copy of the user-manual built in! A final few words; I've already mentioned that one limitation of the Alesis MMT-8 is it's memory so it'll come as no surprise that someone out there has developed a simple way to expand the machine's event capacity. You can find details here. While very cleaver, on this occasion, I advised the customer to consider keeping his machine as original as possible and to avoid drilling holes to fit switches, etc. I'm glad he listened to me. The operating system on this example is version 1.08. To the best of my knowledge, the last version issued by Alesis was 1.11. Changing the firmware isn't difficult and only involves opening up the case (four screws), pulling out the EPROM and inserting the new one (the right way around, of course). I'd advise checking the revision history before doing that however, as the whole exercise might not be something that's relevant to the way that you use the machine. I'm aware that an OLED module suitable for use in other Alesis equipment of the same era, was made by Winstar. I'm uncertain however, as to whether this unit is still available. Another Winstar product code I've seen around, is WEH001602DBPP5N00000 and at the time of writing, this unit is available. If you're interested, then it might be worth checking out. Any display you consider, should have a 14-way connector, be 16 x 2 character and measure 85mm x 30mm. Alesis released a second version of the MMT-8 but it's really quite difficult to find any info' on it. Some suggest that it was a limited edition version, others believe that it was a Mk II and addressed some of the issues in the well-known grey version. If you know anything about the infamous black Alesis MMT-8, please do let me know. Technically, this this refurb cost more than the unit is probably worth and quite honestly, I would have dissuaded the customer from proceeding if the machine wasn't in such pristine cosmetic condition. The customer absolutely loves his MMT-8 and like many refurbishments, it's not a case of monitory value. On the other hand, it's something you need to balance up. So, if you're in a similar situation and considering either an Alesis MMT-8 repair and refurbishment or giving a little TLC to any other bit of gear that you really love, then just message me. UPDATE - 24th November 2020 Okay so I couldn't help myself and, at my own expense, I bought a Winstar WEH001602DBPP5N00000 from Rapid Electronics, SKU is 60-9686 and it arrived this morning. After checking the pin assignments, I soldered a 14-way connector on to the module, plugged it into the MMT-8 and hey, it worked! It looks great! I mean it seriously looks good but being lower than the original (and the replacement I bought from circuitbenders), it doesn't butt up against the inside of the display window. Ironically, the viewing angle is therefore slightly reduced, LOL. At more than two-and-a-half times the price of the circuitbenders' LCD module, you need to think carefully if considering the Winstar WEH001602DBPP5N00000 as an option. A couple of things to mention; on the original LCD module, the contrast voltage is delivered to pin 3. This is not connected to anything on the Winstar OLED as OLEDs don't have a contrast control. Also worth noting is that Winstar makes several different coloured versions of the WEH001602D, so if you don't want blue, you might find a colour that does appeal to you. 🙂... Roland SBF-3253 November 2020Recently, one of my customers brought in a Roland MKS-80 for repair. Well, no surprise there but... Tom also brought me a poorly sounding Roland SBF-325, one of the best ever flanger / chorus units ever made.... in my humble opinion. Roland brought out the SBF-325 in 1979 and before things were designed with built-in obsolesce, this machine was on the market for seven years, just before I joined Roland (UK) Limited as Group Technical Manager in fact (oh, those were the days). The SBF-325 reeks analogue. So much so, that if not tuned properly, you'll easily hear the LFO leaking into the audio via the Matsushita MN3007 bucket-brigade-delay-lines (BBDs). When set up correctly however and in accordance with Roland's service notes, this thing just sounds sweet. The Roland SBF-325 is of course, a stereo flanger with three modes; mono (only Channel A is actually active but is split later on down the line to the two outputs), stereo and stereo with cross-mixing which outputs an extra wide stereo flanging effect by incorporating panning between the two delays. The chorus was obviously designed to deliver Roland's famous, tried and tested chorus sound of the time and I guess there just wasn't a need to mess with it. The Juno-106, the JX-3P, the Boss CE-1 and so many more machines, used the very distinctive, smooth but rich Roland chorus effect. In chorus mode, the modulation section works as it should but the feedback control doesn't do anything. Why would it? The modulation section is very comprehensive with all the usual controls you'd want on a unit like this; centre frequency, rate (speed) and depth. For flanging in particular, 'feedback' is also important. Now-a-days manufacturers seem to have the need to bung on a load of stuff that only they know what it does and that 'we' don't even want. The simplicity of machines like the SBF-325 reminds us of a time when things were just simpler but sounded new and cool! The input and output levels are switchable between -16dBm and +4dBm. Unfortunately none are balanced, something that we take for granted, now-a-days. Actually, the sockets aren't PCB mounted which means that you might be able to make balanced inputs and outputs. Hmm... I have to think about that. With input and output sockets on both the front and rear of the unit, there are also various options to invert one output with respect to the other and even invert the modulation on Channel B. Best of all however, is the provision for CV. Pre-MIDI, the front panel 'Ext CV In' jack, allows the LFO on the SBF-325 to be clocked from another machine including an external LFO. Even today, using a MIDI-to-CV converter, it's easily possible to link the SBF-325 to your DAW. How cool is that? So, Tom has quite a lot of American gear and indeed this unit was a 117V example, as was the MKS-80 he brought me. He told me that the unit was distorting and to be honest, I kind of had an idea what might be causing this. From a service perspective, the problem with this early Roland stuff is that while the service notes go into as much detail as ever, the PCB is really quite difficult to navigate. Roland had this weird finish on the components side of their PCBs which after several minutes, can make you a little dizzy and trying to read component references is almost impossible. Having said that, the tracking on the underside of the board was graphically copied to the components side so once you got used to the bloody thing, this aspect of the board design could work in your favour. So it took me a while to switch into 'Seventies' mode but it soon became apparent that one of the BBDs wasn't biased properly. Okay, not a problem, I thought. Let's go through the process. Ah! I couldn't actually bias it and soon found out why; a little resistor had gone way out of spec'. Ten minutes to change that and let's try again. Wow! We have no distortion in any of the flanger modes but... there were artefacts still present on channel B when in chorus mode. On top of that, it was obvious that there was excessive LFO clock leakage into the audio on the same channel. The age of this machine made it a perfect candidate for a BBD swap-out and so I dropped in a pair of new Xvive MN3007s. Tuning out the LFO noise is a little tricky on these machines as the pre-sets are so incredibly sensitive but I got there in the end. Once the machine was distortion and LFO leak free, I cleaned all of the pots and switches. It seemed that they'd never been touched since the machine was made and I have to say, dialling in parameters suddenly felt and sounded very smooth, indeed. Ah, that's more like it. Be warned however. If you're used to plug-ins or even digital processors, you might hear things in this old analogue gear that you don't like! There's a lot more interaction between harmonics and so the sound is more 'organic' than that of a digital processor or a bit of software. At some frequencies, things happen which might seem a little unexpected. This gives machines like the SBF-325 a certain character and it's not everyone's cup of tea. On the other hand, this is proper analogue flanging and chorusing as they were meant to be. I love this stuff. I really do. In fact I'm actually thinking of designing a modern version of this classic analogue processor, perhaps using MIDI for external control instead of CV and give it some memory, too. Now there's a couple of ideas... In the meantime, if you have a vintage effects processor like the Roland SBF-325 that needs a little TLC, give me a shout. Like I said, I just love this stuff.... The Roland IR3R03 VCO30 October 2020There are several differences between the Roland MKS-80 Rev 4 and the Rev 5, undoubtedly the most significant being that the former used the Curtis CEM3340 VCO while the latter used Roland's own IR3R03. Perhaps the other differences are as a result of this change. Curtis Electromusic re-released their CEM3340 in 2016. The new device is known as the CEM3340 Rev G and information on it is readily available. Here's the data-sheet available on the Curtis Electromusic website. Unfortunately, the same can't be said of Roland's replacement and I was only able to find a single resource, on-line. Being the size of a postage stamp, I decided to knock up this version (pictured below) for anyone who might need a little help with a faulty MKS-80 Rev 5 or who just wants to know how this thing works. From my own experience, the Roland IR3R03 seems to be a little more robust than the Curtis device and I find it quite frustrating that people assume a duff chip when fault-finding a problem on a Rev 5. Before you do that, please check out other stuff like capacitors (hint, hint). You can download a pdf of the above image here. Over the years, I've heard several theories as to why Roland developed its own VCO but it should be noted that the IR3R03 wasn't just a replacement for the CEM3340. It also removed the need for Roland's infamous EHM-S226W83S; the so-called hybrid chip which was used to synchronise the Curtis VCOs. The IR3R03 also reduced the number of components that comprise the cross-modulation circuit. Doing all that, you'd be forgiven for thinking that the voice-boards in a Rev 5 should look a little sparse compared to its predecessor. NOPE! The insides of both versions bear an uncanny resemblance to what was under the bonnet of my first couple of Jags! If you're not technical or simply don't want to open up your MKS-80 to find out which revision it is, then it's pretty easy to suss things out from the serial number. According to the second edition service notes of April 1985, the revision changed after serial number 511800 (inclusive). So, if your serial number is higher than that, you've got a Rev 5. Okay, so the whole point of this post was to host the IR3R03 spec' sheet that I knocked up but... ya' just know that people researching the CEM3340 are going to have this page pop up somewhere in their search results. I've already mentioned that Curtis re-released this very famous chip so there's actually a lot of information already out there but it might not tell you the answer to this question: What's with the white dot? Just about every MKS-80 Rev 4 I've ever opened up has 'white-dot' CEM3340 inside. Each chip has literally a white mark on it. Well, Roland actually graded a lot the chips as they came in from various manufacturers and the CEM3340 was definitely no exception. According to Roland's service bulletin 100248 and without going into too much detail, the white dot CEM3340s had better low frequency response and linearity than the CEM3340s that were marked with a red dot and I bet you didn't even know that there were red dot CEM3340s. Mind you, I don't think I've ever seen red Tipp-Ex, LOL. 🙂 So the next question would be; “If I need CEM3340s replaced in my MKS-80 Rev 4, is okay to use the re-released version? Do they sound the same as the Roland white-dot chips?” That’s actually two questions but… You know I previously used the term “without going into too much detail”? Well perhaps there’s a couple of points which I should mention; Roland did NOT actually specify white-dot CEM3340s for the MKS-80! The specially graded chips were destined for machines like the SH-101 and Jupiter-6. The other point I need to make is that chips weren’t graded to make certain models sounds better but for the following reasons: Testing devices supplied from other manufacturers prior to fitting reduced the number of faulty units that came off the production line. You have to remember that this was the beginning of the eighties. When I was at Simmons, we had horrendous problems because we didn’t do that! The use of graded devices meant that the set-up time of machines after production was greatly reduced. Both of those reasons meant that Roland could keep costs down. Now then, comparing the CEM3340 Rev G with the original white-dot Roland graded chips isn’t something I’ve gone out of my way to do, suffice to say however, that I have refitted many MKS-80s with Curtis’ newer version and I’ll be damned if I can tell the difference! Others have done comparisons. Check out Gregory Cox’s video on the Synthtopia website. So there you have it. I started writing a post about the Roland IR3R03 and half of it is about the Curtis CEM3340! I think I need to focus more...... Eddie Van Halen R.I.P.6 October 20201978 and I remember vividly putting Van Halen (self-titled first album) on to the turntable. The expression 'Blew my mind' has never been so apt and indeed, Eruption changed the sound of guitar forever. Suddenly everything before was just two-dimensional and mediocre. Finger tapping, shredding, a very articulate and defined sound with oodles of sustain (the brown sound), it all started here. A Strat with humbuckers, a Marshall 1959, a little MXR phaser pedal and a whole lotta talent. Van Halen was the talk of the town… for many, many years. He influenced a whole generation of guitarists and the very sound of rock for an entire decade. If there was one thing absolutely annoying about Eddie, it was that he made it all look so effortless! A true natural, many didn’t know that he actually started playing drums with his brother Alex on guitar. One imagines divine intervention that made them swap! Iconic, people like Eddie Van Halen were supposed to be immortal, live forever but of course we’re all just human. From a humble Dutch immigrant background, Eddie’s life was inspirational, not just his guitar playing. EDDIE VAN HALEN R.I.P 6th October 2020 You will be missed... Roland MKS-80 Repair and Upgrade29 September 2020Towards the end of the summer, one of my regular customers brought me a Roland MKS-80 for repair and full upgrade. While previously upgrading Jay's MKS-70, I mentioned my Aurora project to him and also showed him one of Guy Wilkinson's OLED modules that I'd installed in my own MKS-80. Jay was already familiar with my Live Forever battery upgrade. Jay bought his Rev. 5 from Japan and while in excellent cosmetic condition, it did have a fault. Depending on the tone and parameters, one of the voices was either distorting or not tuning properly. 🙁 After learning about Aurora and seeing one of Guy Wilkinson's OLED modules in the flesh, Jay was keen to have his MKS-80 upgraded as well as repaired. As it turned out, Jay was going to be my very fist Aurora customer and we were both very excited. Then, on 12th August, things turned upside-down for me as Hemel Hempstead got hit by a storm which overwhelmed many drainage systems, including one which was in the road leading down to the rear of my premises. Within ten minutes, my studio floor was under more than 20cm of dirty flood water. Over subsequent weeks, My wife Julie, my youngest daughter Tsunami and I cleared out the rest of the studio. The lab was left 'till last however, as I had several customer units which were in mid-fix, Jay's MKS-80 being one of them. I also had to dry out and repair a lot of my own gear. It been a heavy few weeks with very little sleep. Before proceeding with any upgrades, I wanted to fix the distortion / detune issue on this machine. The MKS-80 is very involved and the interdependencies between the analogue sections and even individual components, can yield some very surprising and unexpected results. Despite knowing this machine inside-out, fault-finding isn't always that straight-forward. I got there in the end though and changed two CEM3360 VCA chips, always dropping in turned-pin sockets when I do swap out ICs. I'd already built and installed Aurora into my own MKS-80 so I was confident on the process and that it all worked. Doing the same for someone else's unit is still a little daunting, though. I love the Roland MKS-80 and know it really well. So if you have one that's in need of repair or perhaps you're even considering one of the upgrades mentioned here, please don't hesitate to get in touch. In the meantime, you can read about Aurora here and my RE-MKS-80 rack-ears here. Visit my shop to check out prices for my Live-Forever battery mod and installation of Guy Wilkinson's OLED module.... Flood17 August 2020Probably every studio owners' worst nightmare... Last Wednesday (12th August) at about 3:30 in the afternoon, we experienced heavy thunder and lightning accompanied by the most horrendous down-pour. I had popped out for a cigarette and the wind was seriously blowing. Then it went dark. I figured on making a dash home and swapping my cars over. While at home, I received a phone call from Yvonne, the manager of BlueBox Storage Limited, Hemel Hempstead (where my studio is), requesting that I return as soon as possible. I grabbed a pair of wellies, while my heart sank as I just knew what had happened. It was some time after 5:00 by the time I arrived at the BlueBox Stoage building and standing at the top of the steps leading down to the entrance of my studio, I was horrified to see the water gushing out of the building. My vintage 1979 Roland JC-120, vintage 1969 Fender Vibro Champ, my collection of vintage pick-ups, my Marshall Silver Jubilee cabs, thousands of pounds worth of custom multi-cores and other cables, all hand-made and so, so much more that I haven't even seen yet, all gone in minutes. I simply can't begin to properly convey my heart-break and sense of devastation but even now, I'm not sure if the gravity of it all has actually sunk in yet. I'd just like to give out a big THANK YOU to my wife Julie, my daughter Tsunami and my friends Tony Burlinson, Adam King and Mike Barrett for responding so quickly and helping me move as much stuff to safety as quickly as possible. I think we got pretty much most of the studio gear out by early the next morning. I'd also like to thank all of my Facebook friends for their kind words of sympathy and support. Yvonne and the landlords responded really quickly and things started to happen the next day so of course I thank them for all their efforts, as well. ... Aurora Replacement PSU for the Roland MKS-8017 July 2020Aurora - the world's first replacement switched-mode power supply for the Roland MKS-80.The Roland MKS-80 is an amazing piece of equipment and a lovely sounding machine. As one of the last all-analogue-voiced synthesisers, I am hopeful that Aurora, a replacement power supply for the Roland MKS-80 will keep all of those gorgeous modules still left on the planet, working just a little longer. Anyone who has a Roland MKS-80 with a power transformer that’s not native to their region, now has the option to upgrade the power supply in their machine and plug it straight into their mains supply, without the need of going through an external transformer. Anyone with a Roland MKS-80 that has a bad power supply or broken transformer, can now bring a new lease of life to their machine. Also bear in mind that the old FR2 PCBs are now very brittle and prone to dry joints and even cracking. At the time of writing, some Roland MKS-80s have been operating for thirty-six years! While designed extremely well, the power supplies are stressed systems (as in any machine) and the last thing any MKS-80 owner wants is for the power supply in their machine to go south. IC1 on the original PSU for example, is a M5218L. It's a crucial part of the +5 V supply and the 10 V reference circuit. If this packs up, the +5 V rail could rise to values that could seriously damage your MKS-80 and even make it unrepairable. As time goes on, the likelihood of this happening, only increases. The +/-15 V supplies which drive the voice boards, are a little more robustly designed. Electronics in general doesn’t like heat. Aurora runs much cooler than the equivalent linear power supply. Over time, your MKS-80 may develop transformer born hum. This can't be 'filtered' out and you're kinda stuck unless you can acquire a replacement transformer. Hey, you're in luck 'cos Aurora doesn't produce any hum! Originally, Aurora was going to copy the footprint of the original MKS-80 power supply. A single L-shaped board however, would have meant a lot of wastage and potentially necessitate the removal of the front panel to replace the original mains wiring which would have been too short to reach the single PCB. The solution was to split Aurora into two PCBs; Board A being the main part of the power supply and Board B taking care of mains protection and filtering. I made use of the reinforcing plate that's underneath the original transformer. The size of board B is the same size as this plate. I simply added four M3 mounting holes. This all provides for a very tidy and cost-effective solution that requires minimal reworking of existing wires, etc. Aurora's 10 V reference source started out as a precision circuit using 0.1% tolerance components and a high-grade op-amp. The results were impressive but later, I changed the design and incorporated a multi-turn trimmer so as to allow for adjustment of the reference which may result from component drift over time. Each supply has it's own status LED. I thought this would be a nice addition and in keeping with the original design although unlike the original, Aurora has a different coloured LED for each supply, including the 10 V reference. Also note the test points allowing for easy checking of all voltages. So I was going to teach myself Arabic or Mandarin during lock-down 2020 but instead, I kind of decided to design this. It just seemed like a really cool thing to do! 😀 😎 You can read about the development of Aurora Replacement Power Supply for the Roland MKS-80 here. INSTALLING AURORA Installing the Aurora boards requires a certain degree of knowledge, experience and skill. I therefore insist that the installation be performed by a suitably qualified technician. Aurora is a power supply that converts mains voltage to several DC voltages that your machine requires. Safety is paramount and although fully tested prior to shipping, I strongly recommend that you test Aurora outside of your machine prior to installation. Since there is mains voltage on both boards, care should be taken that the boards are lifted clear of any work surface during such testing, using for example, PCB stand-offs (spacers). Removing the original power supply including the transformer also requires a certain degree of knowledge, experience and skill. Remember that these machines are over thirty years to over thirty-five years old. The voltage distribution headers for example, are soldered to the board. The pins on the headers are not conventional straight pins. They're arrowheads and have a tight fit. Once you're confident that you've removed all of the solder, gently prize them off the board (GENTLY). I suggest that you wiggle the connector from the component side while observing the underneath so as to ensure that all pins are indeed free. Don't simply cut the wires to the transformer and the terminals on the original power supply board. Instead, try to unwrap so as to preserve the original length of wire. You may trim some of these later but you don't want to be left short! Require tools and equipment are as follows: Temperature controlled soldering station (e.g. Weller WE1010) Temperature controlled de-soldering station (e.g. Duratool D00672) Small wire cutters Small pointed pliers Adjustable cable strippers Set of cross-head screwdrivers Small flat-head screwdriver Set of box-spanners (metric) Tweezers Digital multi-meter (DMM) PLEASE don't use a plumber's or electrician's soldering iron and please don't use a manual solder pump. You'll just wreck things. In fact, if you're thinking of using that kind of equipment, you shouldn't be operating on your MKS-80, let alone installing Aurora! A few hints on workflow: Do NOT rush it! Take your time. Check and double check your work after each stage. Do not rely on the status LEDs as indicators of required voltages. Use the test points to measure the voltages with a DMM. When removing screws and nuts from your MKS-80, use a 'gently, gently' approach. You really don't want studs to loosen or threading to shear. Do NOT over-tighten screws and nuts. You're dropping a replacement power supply into a vintage synth module and not building a spaceship that's destined for the outer planets! The 10 V reference has been set by me using a regularly calibrated DMM. Please do not mess with it!!!!! Note the orientation of the headers before you remove them. It's actually not too important other than to keep things tidy except... for P7. Unlike the other headers which each carry a single supply, P7 carries the 9 V supply and a digital ground, to the programmer (MPG-80) port via the output board. It's VERY important that this connector's original orientation is maintained. Your MKS-80 MUST BE EARTHED. If you have a 2-pin IEC mains socket, you must replace it with a 3-pin IEC C14 socket. The earth pin should be connected to Aurora Board A and Aurora board A should then be connected to the chassis. There's a hole in the lower case in between the mains socket and the side of the MKS-80 chassis which will take a M4 screw. DO IT!!!! Aurora board B must also be connected to this point. Here's a wiring diagram showing how the two Aurora boards are connected to each other, the mains input, the switch and earth / chassis. Also illustrated is the use of existing (original) wiring as well as some new wiring. UPDATE - 7th October 2020 Since August's flood, I've had to move ops back home, temporarily. It's very cramped, things are taking longer (it took me two days to find my oscilloscope) but Julie my wife, is amazingly patient and understanding and a big support during this challenging time. I currently have three MKS-80s in for Aurora and OLED module upgrades. Two of them have already been done but the fourth (a Rev 4 at the back), has a dead voice which I need to fix before I do anything else. UPDATE - 2nd December 2020 So the past few months has seen more than a few Aurora sales and installations. Many customers whose units I've had in, have asked if I could also install my Live Forever memory back-up battery mod and it got me thinking. Aurora has two boards. Board B comprises mains protection and filtering so, not a lot. With a little nudging, I was able to fit a CR123a battery holder on to the PCB and so Aurora Bx Board was born! Read more about it here. UPDATE - 24th December 2020 Aurora installation instructions are now available in German. Die Installationsanleitung für Aurora ist jetzt in deutscher Sprache verfügbar. UPDATE - 24th April 2021 Aurora is now offered with the optional V06 data cartridge re-enforcement bracket. Such a cool solution to a problem that many Roland MKS-80 owners will be familiar with, the V06 basically strengthens an undamaged cartridge slot and reinforces a broken one by putting 2mm of solid steel behind it! Existing Aurora customers take note; once your Roland MKS-80 is open, V06 can be installed in a few minutes, with just a M3 (5.5mm) nut-runner. Read more about the V06 here. I'm deeply concerned about the environment and the exploitation of labour and so I always use local manufacturers in preference to the Far East, with the following in mind: I can be confident that workers are treated fairly and earn a proper wage. I can be confident of the standard of quality of each item that is delivered to me. Communication is important and using local manufacturers, all correspondence is quick and understandable. I believe in supporting the local economy. I can be confident that the disposal of manufacturing waste is managed properly and in accordance with national and EU law. Using local manufacturers isn’t the cheapest option but the above points are important to me. I hope that they’re important to you too. Please don't hesitate to contact me if you have any questions regarding the Aurora Replacement Power Supply for the Roland MKS-80 or, if you want to buy Aurora or book in your MKS-80 to have it fitted, please check out my store.... Roland MKS-80 Output Phase Correction17 July 2020I often receive questions regarding the Roland MKS-80 output phase correction mod' and without meaning to do myself out of taking your money, I do feel it necessary to ask whether or not you actually need it! Once upon a time, there were two conventions for delivering a balanced signal via a XLR socket. Both conventions (fortunately) used PIN 1 for earth (0 V). They differed however, in as much that one used PIN 2 for the positive (+), in-phase signal and PIN 3 for the negative (-) out-of-phase signal, while the other used PIN 3 for the positive (+), in-phase signal and PIN 2 for the negative (-) out-of-phase signal. Back in the day, it was theorised that US and European manufacturers used the first convention while Japanese manufacturers used the second. In the eighties and nineties, I designed and built a lot of recording studios, live performance systems and guitar racks (remember them) and I can tell you that it didn’t really matter who built the gear, stuff was all over the place. You just had to check. SO WHAT DOES THIS MEAN ANYWAY? Good question! Most of the time, you can actually ignore the convention used for sending a balanced signal to a XLR socket as it’s all ‘relative’. What I mean by that, is that if the output is from a synthesiser for example and you’re only using the balanced XLR outputs, then if the signal is ‘upside-down’, it’s not actually going to make any difference! If however, you’re using the balanced XLR outputs from a synthesiser and the unbalanced jack outputs, then you will have a problem as the signals on the XLRs will be out of phase to the signals off the jacks, as seen by the mixer those signals are going into. If the amplitude of both sets of outputs is the same, you will in fact get absolutely nothing as the two pairs of outputs will of course cancel out each other. You can easily get around this by either phase inverting the respective inputs on your desk or DAW for one set of outputs or by swapping pins 2 and 3 in the XLR connections at one end (only) on the cable between your gear’s XLR outputs and your desk or DAW. In a recording environment, it’s preferable to use balanced +4dBm so your Roland MKS-80 should only be connected to your desk, using the balanced XLR outputs. If that’s the case, then there’s no need to do anything. Where phase becomes an issue is when signal processors are daisy-chained, like in the old massive guitar racks from the eighties or… (as previously mentioned) if you’re using both XLR and jack outputs. You may just want everything to be as standard as possible in which case, things can be done internally with a very simple procedure. So, if you do want the Roland MKS-80 output phase correction mod', then please don't hesitate to contact me.... Rack Ears for the Roland MKS-8013 July 2020Following on from my last post 'RACK EARS FOR THE ROLAND MKS-70', I thought I'd better put this one up too, just to make it clear that I also have rack-ears for the Roland MKS-80. As it turns out, these rack ears will also fit the following Roland 2U modules: Roland MKS-7 Super Quartet (released 1986) Roland MKS-10 Planet-P piano module (released 1984) Roland MKS-20 Rack mount version of the RD-1000 digital piano (released 1986) Roland MKS-30 Rack-mount of the JX-3P synthesiser (released 1984) Roland MKS-100 Rack mount version of the S-10 sampler (released 1986) Roland DDR-30 Electronic drum module (released 1985) If you have a MKS-80 Rev 4, then you'll only use three screws each side. Yes, that's right; Roland didn't standardise the rack case 'till the Rev 5 was released! Please note that these rack ears are only available in black and as a pair. Just like the originals, these rack ears are made from aluminium with a black anodised coating and horizontally running mill finish. Apart from looking superb, they fit perfectly. Supplied with eight black countersunk M4 machine screws, all you need to fit them, is a screwdriver. 🙂 I'm now happy to announce that these rack ear kits are available to purchase. UPDATE - 6th May 2021 I finally got replacement rack ears for the Roland MPG-80 made up recently. Check 'em out here. I'm deeply concerned about the environment and the exploitation of labour and so I always use local manufacturers in preference to the Far East, with the following in mind: I can be confident that workers are treated fairly and earn a proper wage. I can be confident of the standard of quality of each item that is delivered to me. Communication is important and using local manufacturers, all correspondence is quick and understandable. I believe in supporting the local economy. I can be confident that the disposal of manufacturing waste is managed properly and in accordance with national and EU law. Using local manufacturers isn’t the cheapest option but the above points are important to me. I hope that they’re important to you too.... Rack Ears for the Roland MKS-7013 July 2020I've been meaning to do this for a very long time and finally, over lock-down, I decided to design a pair of rack ears for the Roland MKS-70. I produced some plans from the rack ears of my own MKS-70 and this morning I got a text informing me that the prototypes were ready to collect. I didn’t bother getting these anodised as I wanted to be sure that they fit properly. Well I have to say that I’m pretty chuffed with myself and Lenton Engineering in Watford. Always following my drawings precisely and consistently delivering perfect prototypes for me since 1985, I just love these guys. Please note: These rack ears do NOT fit any other Roland module Only available in black Only available in pairs Just like the originals, these rack ears are made from aluminium with a black anodised coating and a horizontally running mill finish. Supplied with eight black M4 countersunk machine screws, all you need to fit them, is a screwdriver! 🙂 I'm now happy to announce that these rack ear kits are available to purchase. IMPORTANT: Shipping price is for worldwide delivery. 🙂 I've also designed a pair of rack ears for the Roland MKS-80, which again were based on the rack ears of my own unit. These are more versatile than the MKS-70 rack ears and fit several Roland modules from the eighties. Check out this post for details. I'm deeply concerned about the environment and the exploitation of labour and so I always use local manufacturers in preference to the Far East, with the following in mind: I can be confident that workers are treated fairly and earn a proper wage. I can be confident of the standard of quality of each item that is delivered to me. Communication is important and using local manufacturers, all correspondence is quick and understandable. I believe in supporting the local economy. I can be confident that the disposal of manufacturing waste is managed properly and in accordance with national and EU law. Using local manufacturers isn’t the cheapest option but the above points are important to me. I hope that they’re important to you too.... Guitar Cab Impedance Explained12 June 2020Guitar cab impedance and hence, connection can sometimes be a bit of a mystery but is critically important if for example, you’re using valve amps. That’s amps which have a valve power amp. If you have an amp that has a valve pre-amp section and a semi-conductor (transistor) power amp section, then it’s not a big deal. WHY IS IT SO IMPORTANT TO CORRECTLY MATCH UP CABS WITH AMPS? The valves in your power amp don’t connect to your cabs directly. Instead, they go via a transformer. The job of the transformer is to match up the output impedance of the valves to the input impedance of your cabs. Impedance is like resistance. It’s even measured in Ohms (Ω). Unlike resistance however, impedance is different at different frequencies and so varies depending on the frequency at which it is measured. To keep life simple, the impedance of a system is specified as an optimum, meaning that although the impedance changes as the frequency changes, the specified impedance is a particular quantity plus or minus so much. The impedance of for example, an 8 Ohm (or 8Ω) cab is roughly 8 Ohms across the used audio spectrum, plus or minus a bit. BIG DEAL. SO WHAT HAPPENS IF I GET IT WRONG? If there is an impedance mismatch between a valve amp and its load (the cab that it’s connected to), the transformer in the amp is put under stress. This stress will burn out the transformer, your amp set-up stops working and you’re definitely in for a very expensive repair. If the connection between your amp and your cab is broken and becomes what’s known as ‘open circuit’, then the same thing will happen. Effectively, your amp’s output has been set to drive a specific impedance. With nothing attached, your amp is trying to drive an infinite impedance; BANG!!!!! I’VE GOT LOADS OF CABS. HOW DO I KNOW WHAT IMPEDANCE TO SET MY AMP TO? Like anything, it’s actually quite simple if you remember a few basics. For starters, it might be worth noting the following: Speaker cabs come in combinations of one, two or four speakers. Virtually all individual speakers in all cabs are 16Ω. The impedance of the cab itself, is a combination of the 16Ω speakers that are inside it. I’ll show you how to work that out in a minute. Once you know the impedance of individual cabs, there’s a simple way to work out the impedance of all the cabs connected to your amp. The last point is the most important; there are exceptions! While most manufacturers follow the rules and apply them to most of their amps, that’s not always the case. The Roland JC-120 is a classic example and I’ll show what I mean a little later. So, let’s have a look at cabs. The simplest cab is the humble single speaker cabinet like a 1 x 12”, for example. With a single 16Ω speaker, the guitar cab impedance is (you guessed it) 16Ω. A dual speaker cab will comprise two speakers of the same impedance (usually 16Ω). These will be connected in parallel. When resistors and impedances are connected in parallel, the combined resistance or impedance is worked out as follows: 'Z' is the engineering notation for impedance, so Zt is the total cab impedance and Z1 and Z2 are the impedances of the two speakers respectively. Of course since the impedance of the individual speakers is the same, the formula becomes quite simple, like this: So to work out Zt (the overall impedance of our 2-speaker cab): So you might have noticed that two speakers of equal impedance, connected in parallel, have a combined impedance of half of the impedance of one speaker... you have noticed right! If you’re still with me, let’s throw in some numbers. Let’s start by remembering that our speakers are 16Ω each: And of course, 8Ω is the correct answer! The impedance of a 2 x 12” cab comprising two 16Ω speakers is 8Ω. That’s because they’re connected in parallel. The combined impedance of series connected speakers (one after the other) is much simpler; you just add ‘em up. So if for example, our two speakers in the cab above were connected in series, then the combined impedance would be 16 + 16 = 32Ω. This doesn’t actually happen, well not to my knowledge. Cabs with four speakers combine series and parallel wiring to achieve a combined impedance of 16Ω. Modern cabs have two speakers in series which makes 32Ω. Another two speakers in series which makes another 32Ω. The two pairs are then connected in parallel making the whole guitar cab impedance 16Ω. You can of course do this the other way around; parallel / series, achieving the same combined impedance. In fact most vintage cabs are wired like this so two speakers are wired in parallel to make 8Ω. The other two speakers are also wired in parallel to make another 8Ω. Then the two pairs are wired in series to make the whole guitar cab impedance (8Ω + 8Ω) 16Ω. If you're not used to all that arithmetic, it can kind of look a little intimidating. On the hand, if you go over it couple of times, it will hopefully start to make sense. So, cabs can be treated in the same way as individual speakers although cabs are usually connected in parallel inside your amp... err... with one exception (that I know of) and that the Roland JC-120. Firstly, although it's a combo the speakers aren't powered by one amplifier. There are two independent amps, one driving each of the speakers. Secondly and more relevant to this post, when you plug in additional speakers, they're actually connected in series with the internal speakers. Remember that the JC-120 is a transistor amp so impedance matching isn't an issue. What it does mean however, is that the load on each amp, will increase when you plug in more speakers, thereby reducing the power output of the whole amp. Remember that we worked out that 4 x 12 cabs are normally rated at 16Ω? Now consider using two 4 x 12 cabs to make a full stack. Plugging them both into a single amp where they are connected in parallel inside the amp, will make the overall speaker load, 8Ω, just like our very first 2 x 12 example. 2 x 12 cabs work in the same way. Each 2 x 12 cab is 8Ω. Connect two of them to a single amp and the combined overall impedance will be 4Ω so you need to set you impedance switch on the back of your amp, to 4Ω. As with most things in life and as I've said a couple of times in this post, there are exceptions. As I say, the nice thing about standards is that there's so many to choose from! 🙂 Now then, pictured below is the back of a Marshall TSL122 100 Watt 2 x 12 combo. So is this confusing or what? For starters, the speakers in this thing are different. Marshall decided to combine a Celestion Vintage with a Celestion Hertitage. Yeah, I know people do that but I'm not a fan, to be honest. Anyway, the point is that each speaker is 8Ω. On top of that (and the second point), is that they're wired in series to create 16Ω. Well that kind of makes everything I've just said, seem like a complete and utter waste of time. On this particular amp, the on-board speakers are plugged into the (default) 16Ω speaker output, the markings of which are obscured in the picture, by the lead. Plugging into this socket, disengages the other sockets. If you want to use external cabs, you need to unplug the lead going to the on-board speakers, plug into one or both of the other sockets and if your cab impedance is 4Ω or 8Ω, you'll then need to select your impedance appropriately. If you've got a 16Ω cab, you have to unplug the lead going to the built-in speakers and plug your cab into the 16Ω output. That's really confusing and personally, I can't see a way to use the on-board speakers and an extension cab! I'm not a fan of the TSL series but this kind of thing really makes me back off! Then there's the Roland JC-120 which I've mentioned a couple of times, earlier. Not a valve amp so impedance isn't at all a big deal but... it's rather interesting that anything plugged into the speaker jacks around the back, is put in series with the on-board speakers. You have to remember that this thing came out in 1979, so what was Roland thinking? On the other hand, who'd want to mess with the sound that comes out of a bog-standard Roland JC-120? It's gorgeous! GUITAR CAB IMPEDANCE - CONCLUSION So the bottom line is that you need to always check. Read anything that's written on the back of your amp and on the back of your speaker cab. Make sure that you read the manual and if you do get stuck, then you can always just call me! Oh and one more thing; ALWAYS USE GOOD QUALITY SPEAKER CABLE!!!!!!!... Roland MKS-80 Power Supply Upgrade23 May 2020Inspired by the great work of Guy Wilkinson from supersynthprojects.com on his P0004 switched-mode power supply upgrade for the Roland Super-JX, I decided to have a go at designing a similar Roland MKS-80 power supply upgrade. As it turned out, Guy helped a lot. After all, he's done this kind of thing before! For those who might be unfamiliar with how conventional style 'linear' power supplies work, let me briefly explain: Mains voltage goes into the unit. This varies across the world from 240 V in the UK to 100 V in some other places. A transformer is used to ‘step down’ the mains voltage, to something close to what is needed to power the internal electronics. A transformer will often have a couple of 'secondary' windings which produce two or more independent low-voltage supplies. Here's the transformer in a Roland MKS-80. In the MKS-80, you're aiming to get a few more volts than +/-15 V for the analogue electronics and +5 V for the digital. Then you might need a little something for say, a remote programmer. In older synths, you’ll also need a reference voltage for the VCOs, for example. In the MKS-80, this is 10 V and needs to be very accurate. It was also quite common to generate other voltages, sometimes complimentary. In the MKS-70 for example, +/-5.6 V are produced on the CPU-board and in the MKS-80, each voice-board has a small circuit which produces +/-7.3 V. These voltages were derived from main supply lines such as +/-15 V from the power supply. After the transformer, the voltages are still AC meaning that they’re still in a sinusoidal form swinging between positive and negative at either 50 or 60 Hertz (again, depending on where you are in the world). You need to ‘rectify’ these AC voltages which is the first stage to approximating towards DC voltages of a single polarity (plus or minus) and then you need to smooth out the result, with big capacitors. Finally, you need to ‘regulate’ the voltages. The regulator stage performs two jobs; the first is to deliver the actual voltage required. The input voltage to the regulator will be a few volts more than what comes out from the other end. The regulator 'absorbs' the difference between the input and the output voltages and dissipates this as heat. The second job of the regulator is to maintain the required voltage as the demand for current varies. So, you normally have one big transformer with perhaps a couple of secondary windings to bring things down. After the transformer, you'll have a couple of rectifiers and then one regulator (and associated filter circuitry) for each supply. It doesn't stop there. You may have noticed that some power supplies are 'larger' than others. Obtaining the desired voltages is one thing but electronics needs current. The product of DC voltage and DC current is 'power'. So more powerful power supplies are... well, bigger! Still with me? Good! Modern switched-mode power supplies do exactly the same job but work quite differently and probably the main physical difference is the absence of a transformer. This omission is generally a big space-saver. When however, you’re requiring several independent voltages in the same box and you basically need one AC/DC conversion stage per voltage, things can get a little crowded. Switched-mode power supplies are considerably more efficient than their equivalent ‘linear’ cousins so generally they don’t get too hot. Some will be familiar with the sometimes, huge amount of heat-sinking present on linear power supplies and the case venting that used to go with them. Due to the way they work, switched-mode power supplies can be plugged into virtually any mains supply unlike linear supplies which will require the ‘taps’ on input side of the transformer to be changed… if you’re lucky. Some older equipment would require the whole transformer to be replaced, when changing mains voltage! Oh, those were the days. Since that's virtually impossible all these years later, users of equipment that would have required a transformer change to operate in their region, can only opt for using an 'external' transformer which steps the mains voltage up or down from their region to that which the respective equipment was originally manufactured to operate in. What a drag. So, if you have a MKS-80 that you acquired from another region and you use an external transformer, fitting an Aurora module into it, will allow you to plug your machine directly into your mains supply. 😎 So truth be known, both linear and switched-mode power supplies have their respective challenges and if not designed properly, can cause undesired side-effects, compromised performance or reduced life expectancy. In a linear power supply, initial conversion of AC to (a type of) DC is performed by rectifiers, the output of which is 'smoothed' by large capacitors. If not chosen carefully, smoothing might be compromised thereby producing hum. Large capacitors are expensive and take up precious space and over time, the dielectric material inside them deteriorates, thereby reducing their effectiveness. Discrete or comprised linear regulators are very inefficient and can require considerable heatsinking, again increasing cost and demanding even more space. Apart from being a considerable lump of iron and wound copper, transformers generate electromagnetic fields which are seriously not wanted in audio equipment. Switched-mode power supplies also have their issues. If designed like Aurora which comprises discrete AC / DC converters, issues such as switching noise are greatly reduced. Due to the nature of operation, there is no hum. Neither are there large capacitors that will over time, deteriorate. On the backend of Aurora’s AC / DC converters are additional filers to virtually remove further noise. And of course as has been previously mentioned, the efficiency of switched-mode supplies means that there is no requirement for huge heatsinking. Since Roland launched the MKS-80 in 1984, electrical safety standards have changed considerably and it's important that anything designed today, which is to be made available to the general public, complies with modern regulations. In fact the decision to make something like Aurora, which potentially can be fitted by 'anyone' was the hardest. On the other hand, there are disclaimers! Follow the rules and everyone should be just fine. A CHANGING WORLD It’s Spring 2020 and the world has been hit with COVID-19. Countries try to protect their citizens by declaring lock-downs. It’s a depressing time and hundreds of thousands die across the world while many are left alone with the stress of isolation. 2020 is turning into a time for reflection and the global community begins to realise that things might never be the same again, at least for the foreseeable future. I was lucky, very lucky. I was at home with my lovely wife and one of my daughters who had come back from university, just before the lock-down was announced here in the UK. After a few days, I set up my laptop on the dining room table and came up with a couple of projects, simply to pass the time. One of them was 'Aurora'; a Roland MKS-80 power supply upgrade. I won't bore you with the other ideas. A QUICK STEP BACK Just before the lock-down, I had a couple of Roland MKS-70s come in for repair. Having one of these gorgeous synth modules myself, during the repair process, I got quite into the world of Super-JX upgrades. You can read more about that here. Having got to know Guy Wilkinson and also being the proud owner of a Roland MKS-80, one thing led to another. The first two or three weeks were spent making physical measurements. I needed a board size! Since the massive heat sink would be redundant, I planned to take advantage of that space. Measuring, re-measuring and measuring again... many of the spaces between the mounting studs didn't seem to be exact integers, hence there was always a glimmer of doubt in the back of my head. The design started off with the idea of using the same board dimensions as the original MKS-80 power supply. I just extended it to take up the area that was occupied by the heat-sink. As things progressed however, it was obvious that this would be an expensive approach and any consideration of commercial supply would be ridiculous. The PCB would require a panel measuring a massive 280mm x 210mm. The board is L-shaped and so, after cutting, that would mean a wastage of over 35%. The board would have been way too expensive to have been viable so annoyingly and after several design revisions, I decided to completely change my approach to using two boards; one, a regular rectangular shape, which would occupy the main area of the original board and heat sink and which is known as Board A and a second board which would accommodate the front-end high-voltage components and which would mount where the original transformer was, known as (you guessed it) Board B. I must confess that despite having spent the past thirty-five years servicing studio equipment and having been Roland UK's Group Service Manager in the late eighties, I was still very apprehensive about operating on my own lovely MKS-80, which is in beautiful condition. Unlike the MKS-70, the connectors that distribute power to the CPU-board, voice-boards and output-board, are grouped by voltage as opposed to destination. This means that all the +15V supplies are on one connector, all the -15V supplies on another and so on. Also unlike the MKS-70, the connectors are soldered at the power supply end, to the PCB. Another consideration was the classic Roland nice 'n' tidy wiring loom. Ideally I wouldn't want to mess with that so I figured on trying to preserve the relative positions of the header connectors as best as I could. There are two other marked differences between the MKS-80 and MKS-70 power supplies; the MKS-80 has a precision 10V reference source, used for the VCOs. It also has cute little status LEDs which indicate power on the various voltage output lines! Anyway, after some time, I felt as though I'd done enough measuring and so the next stage was to work out the current demand on each line. The unregulated supply wouldn't want too much as it's used to power a MPG-80 programmer / editor, when connected. According to the Roland service notes, the power consumption of the MPG-80 is 0.9W. With on-board 5V regulators, that means that the current drawn is about 180mA. The 10 V reference source is just that, a reference and so current requirement isn't an issue. That means we're left with +/-15V for the voice boards and +5V for the CPU board. I so didn't want to start messing around with my MKS-80, lifting components and possibly even cutting tracks, so I decided to try to work out current requirements from the schematics in the Roland service notes. I also used Guy's results from his P0004 MKS-70 power supply project, as the two machines are kind of similar. Although more expensive, I went for Vigortronix AC/DC converters. Vigortronix is just down the road from me and I've been using their transformers for many years. Technically, the specifications of the Vigortronix converters seemed much better than the Mean Wells with for example, less leakage. After having arrived at current requirement figures, I chose 25W converters for the +/-15V rails and a 15W converter for +5V rail. The power ratings of the converters would theoretically mean that Aurora would run quite cool. For the 'unregulated' supply to the programmer port, I chose the Vigortronix 9V version of the 2W converter which will deliver 222mA. The 9V supply is being sent outside of the MKS-80, so Roland decided to protect it with a 125mA fuse which resides on the MIDI board. I've gone a step further and dropped in a resettable fuse. I decided to use through-hole T-1 3 mm LEDs instead of the surface-mount devices that Guy used on his P0004. I figured it would introduce a little retro into something that's so hi-tec in comparison to the original PSU. Back in 1984, I don't remember seeing anything other than red LEDs. This time around, I decided to give each supply, a different colour. Yeah, what the hell? And don't forget the 10 V reference source. Originally I had no intention of putting a LED on this circuit but I eventually caved in. 😎 As I worked on the PCB design, I still had some concerns regarding the circuit design. Check out the tolerances of the supplies as specified on page 22 of the original Roland service notes: Two of those figures are tight, with about 0.6% tolerance on the +5V and +15V lines. Although not impossible to achieve with the type of power supply that's being discussed here, it's not easy and such tight tolerances could be a problem. Typically, AC/DC converters have an accuracy of between 1% and 3% and of course there's a small voltage drop across each all-important filter. Out of interest, I measured the voltages on my own MKS-80. Here's what I found: +5V line measured in at +5.01V (10mV ∼ 0.2%.) +15V line measured in at +15.08V (80mV ∼ 0.53%). -15V line measured in at -15.10V (100mV ∼ 0.67%). WOW!!!!! And that's after over thirty-five years! Roland sure could build power supplies. Well, this realisation was kind of depressing and potentially the whole project could now be in jeopardy and might even end up being a complete and utter waste of time. 🙁 Incidentally, the Roland Jupiter 6 power supply is very similar and has exactly the same tight tolerances. I carried on carefully studying the service notes. I looked over the schematics many, many times. I just couldn't find any reason for the high level of accuracy specified for the +5V and +15V rails and yet the accuracy for the -15V line was pretty average. The CPU-board should work fine on a little less than (bang-on) 5V. In fact slightly lower would be better. Although the critical 10V reference voltage is initially derived from the +15V rail, the fact that it's adjustable means that not even this would require such a tight tolerance on that supply. So despite the fact that the thought of blowing up my MKS-80 if I was wrong, was constantly at the back of my mind, I decided to carry on. The circuit for the Aurora was actually quite simple, to be honest. The PCB layout however, was not. Guy and I communicated almost every day while I was designing the PCB. In fact I only hope I wasn't too much of a pain for him! His extensive knowledge and experience of power supply filter design however, proved invaluable and we both shared a mutual attention to detail. Quite honestly, I couldn't have delivered this project without his help and so I'm actually considering the Aurora, a co-design effort. Thanks, Guy! UPDATE - 5th SEPTEMBER 2020 Ordering prototype PCBs is a slightly nerve-wrecking experience and by the beginning of August, having made several tweaks to the PCB layout, I was waiting for the fourth and final version to be delivered. Then, on 12th August and after a major storm, my studio got seriously flooded. The experience was devastating. You can read about it here. Sod's law; the day after the flood, my final version PCBs arrived. In fact that week was supposed to be the week that I officially launched Aurora but it all went kinda wrong due to the flood. Once all my gear was safe and I had a plan in mind on how to move forward, I built a couple of Aurora boards and (somehow) found the courage to drop a set into my own MKS-80 amidst the chaos and devastation of the flood aftermath. What was I thinking?!?!? Anyway, I couldn't believe it. A bit of good luck for a change. WOW!!!! It all worked. Measuring the supply voltages, everything looked just perfect with +15.00V, -15.07V, +4.97V and +9.01V using the sample converters that Vigortronix sent me. There was no hum on the audio and it was remarkably quite, too. After an hour of being on, the converters were only slightly warm. This was great news. Over the next few days, I put Aurora through its paces. Like many switched-mode power supplies, Aurora doesn't like being switched on and off in quick succession. That's probably not a good thing to do to your precious MKS-80, anyway. It's not a light-bulb! While my MKS-80 was open, I took the opportunity to fit one of Guy Wilkinson's OLED modules. Okay, so the display on the MKS-80 doesn't really tell you too much but the new OLEDs do look really cool. More importantly, you don't have to worry about the old LCD backlight packing up or the inverter starting to whine. In fact I pulled the coil and the transformer from the CPU board, as they're completely redundant, now. 😎 Anyway... designing Aurora was a challenge but thoroughly enjoyable and I learnt so much. A working modern power supply for the Roland MKS-80. Wow! 🙂 With Aurora now finally working and really well tested, please read my official post here or just buy it here.... USB MIDI Keyboard to MIDI Hardware How To15 May 2020One subject that comes up time and time again is "how to connect a USB MIDI keyboard to MIDI hardware". I've therefore decided to put up this post... It's not exactly difficult but at the same time, you can't take it for granted that the MIDI keyboard you've got your eye on, actually has well... MIDI ports. Just about every controller seems to be designed to plug straight into your computer and hence, only has a single USB port. Manufacturers tend to offer their controllers in versions with those little 5-pin DIN sockets but they're usually upgraded versions with for example, seventy-six keys instead of the sixty-one keys that you wanted and perhaps more to the point, the version that'll fit on your desk or that's within your budget. In a market that has been increasingly dominated by computers, some might concede that it's hardly surprising that MIDI ports are omitted from modern (MIDI) controllers. On the other hand, for those of us that have a collection of hardware sound modules, synthesisers and drum machines, MIDI controllers without MIDI ports is kinda useless! Fortunately there's a potentially very simply and cost-effective work-around; introducing the MIDI USB host! So a MIDI USB host is basically a small box running embedded firmware that recognises any class-compliant USB MIDI controller. That middle bit (class-compliant) is really important. A MIDI USB host is designed to be switched on and left. There's no monitor, QWERTY keyboard or mouse attached and there's no way to access the 'operating system'. It stands to reason therefore, that connecting anything to it, should be immediately recognisable and that means that anything connected to it MUST be class-compliant. Well, fortunately most USB MIDI keyboards are just that but it's always worth checking. Several manufacturers make MIDI USB hosts but perhaps two of the most well known are those made by Kenton Electronics and MIDITech. Be expected to pay about 85 GBP for the former and 66 GBP for the latter. For the DIYers amongst us, I've chosen to include the USB Host Controller Board V2.4 in the image above. Available from https://www.hobbytronics.co.uk/ for a modest 16.20 GBP (at the time of writing), this kit is available in a variety of 'pre-blown' versions, with appropriate firmware put on to the 24FJ64GB002 microcontroller before it's sent out. One version makes this little board into a great USB MIDI host. You'll need to connect 5-pin DIN sockets, provide power and box it up yourself but for anyone who feels a little adventurous, this can be a very cost-effective solution. One point worth noting, is that these boxes require power and both examples mentioned above are equipped with USB power ports that are secondary to the USB port that's used to accept the connection from your USB MIDI keyboard. MONSTER MIDI INTERFACE A company called iConnectivity makes a series of MIDI interfaces that are superbly designed and particularly suited for the modern audio production environment. The MioXL for example, has ten (yes TEN) USB MIDI ports as well as a bunch of conventional 5-pin DIN MIDI ports and... it also supports RTP-MIDI via a RJ-45 connection. Fully configurable via software hosted on your computer, the MioXL also has an elegant OLED display providing an array of status information. Available for under 350 GBP, this is a seriously powerful interface that's designed to connect to just about anything that can carry MIDI. LATENCY Anyone working with digital audio will be familiar with something called 'latency'. Loosely defined as the time between a signal entering a digital system and leaving the same digital system, latency is basically the time taken to digitally process a signal. If that means simple analogue to digital or digital to analogue conversion, then even that process takes a finite period. This is not the case with analogue electronics although there does exist an almost analogous parameter called 'propagation delay' but let's not confuse things just yet, eh? When working with computers specifically, latency can be quite substantial as there's a lot going on in these boxes that we've all grown used to. Having said that, clock speeds and more efficient processing both in software as well as hardware, has reduced latency over the years and in most situations, it's not a real concern anymore. On top of that, manufacturers of audio interfaces introduced 'direct monitoring' a long time ago which was and still is a great work-around to the issue of latency. So going back to our USB MIDI host, it should be noted that by design, the smaller boxes are very simple and are designed to do one thing and one thing only. Hence, while latency technically still exists, simply by the nature of the beast, it is negligible. I use a Kenton Electronics MIDI USB host myself and I can assure you that if latency was an issue, I simply wouldn't bother.... Roland Super-JX Upgrades12 May 2020Following on from my post covering the installation of a replacement power supply into a Roland MKS-70, I decided to do another post on a whole bunch of cool Roland Super-JX Upgrades which I discovered during lock-down 2020. Apologies if some stuff is kinda repeated. Back in April 2020, I got a Roland MKS-70 in for repair. It was powering up but wasn’t booting. While replacing original components that were over thirty years old on the power supply, another MKS-70 came in with err… power issues. This all happened during lock-down so progress on the repairs was kinda slow. I did however, have lots of time to see what I could find on-line. I very quickly came across supersynthprojects.com and over a period of days, got to know Guy Wilkinson, a vintage synth enthusiast with a very relevant background. Guy has developed a switched-mode power supply for the JX-10 and MKS-70. Guy also supplies a variety of displays, one of which particularly caught my attention, the Super-JX OLED upgrade display. As many Super-JX owners will know, the original vacuum fluorescent display (or VFD) as well as the FIP coil that drives it, is just about impossible to get hold of now. VFDs and FIP coils fail, so any potential replacement is well worth checking out, especially if it's going to be OLED cool. I've always wondered why some people use the adjective "sexy" to describe tech'. Guy's Super-JX OLED looks stunning and now I know. I just can't stop looking at it! 😛 As I continued my research into the world of Roland Super-JX upgrades, I came across vecoven.com and the Vecoven PWM upgrade; a kit which provides the Super-JX sounds with pulse-width modulation. WHAT!?!?!?! Fred Vecoven sells the PWM upgrade as a self-assembly kit comprising two small PCBs (one for each voice board), lose components, three EPROMs and two replacement 80C320 processors (again one for each voice board). An option to buy populated PCBs is also available. Neither the self-assembly kit or the pre-assembled PCBs kit are however, supplied with cabling or connectors, presumably because there are several potential mounting options. Guy's website has detailed installation instructions for Fred's PWM kit, both for the JX-10 and MKS-70. Below is a pair of Vecoven PWM upgrade PCBs which I have made up myself. The keen and eagle-eyed will have noticed that the ICs aren't soldered directly to the PCB and that instead, I've chosen to use turned-pin sockets; always a good idea! Fred Vecoven has also rewritten the Super-JX firmware and has developed a flash upgrade module which, apart from increasing the memory to the equivalent of thirty-two Roland M64C cartridges (yes, that's right... 32 x M64Cs), allows firmware updates via MIDI. Fred's firmware also gives you some control over how Guy's displays work. Hey, is that teamwork or what? Well it just so happens that I also have a Roland MKS-70 (yeah, I know... you're really surprised, right?) and all this stuff just sounded soooo exciting. Within a few days, I ended up with a switched-mode power supply PCB and an OLED kit from Guy and a PWM kit and a Super-JX flash module from Fred. My wife wasn't happy. And I thought lock-down was going to be oh soooo boring! I had to buy all the components for the P0004 power supply but conveniently, Guy has a very detailed bill of materials (BoM) on his website. This made components purchase very easy. The OLED module came fully assembled and Guy e-mailed me instructions on how to install it. As previously mentioned, Fred's PWM kit doesn't include connectors and cables so I also had to buy some bits to get this going. Getting to know Guy and Fred was a privilege. In fact, I eventually struck up a deal with Guy and I am now offering ready-built versions of his P0004 switched-mode power supply board, as well as an installation service for this fantastic upgrade and his Super-JX replacement displays. Click here for my prices. If you're fitting the switched-mode power supply module yourself and your MKS-70 or JX-10 has a 2-pin IEC mains input socket, then you must replace it with a 3-pin IEC mains input socket. The replacement switched-mode power supply MUST be connected to earth as must the chassis of your Super-JX. I offer a comprehensive earth bonding kit comprising the following: 1 x IEC 3-pin chassis socket. 3 x pre-cut heat-shrink strips. 1 x insulating boot for IEC socket. 1 x M3 earth tag. It is paramount that if fitted, a 2-pin IEC mains socket be replaced with a 3-pin IEC mains socket and that the chassis and the P0004 are connected to earth. Installing these Roland Super-JX upgrades into my own MKS-70, was hard work but I had a lot of fun doing it and... I got to know a couple of seriously intelligent dudes. My humble contribution to the awesome work that Guy and Fred have done, is a simple bracket which makes mounting the PWM boards into a MKS-70 a little easier. IMPORTANT: Since the bracket secures to the transformer mounting studs, it can only be fitted if Guy's P0004 switched-mode power supply is also installed. The IDC connectors I've used, don't have the tidy fold-over clamp (retainer). That's because those ones are too high and this neat little mounting solution won't work as the whole assembly will simply be too high to fit in the MKS-70's 2U case. The other point to note is that the V01 mounting bracket puts the Vecoven PWM daughter-boards, in very close proximity of the voice-boards. Hence and unlike if mounting the Vecoven PWM daughter-boards to the voice-boards, vertical and NOT right-angle IDC headers must be fitted to the PWM boards. I wasn't going to offer this bracket as an item as it didn't seem worth it but I've been persuaded to get some made up and so I’m selling them with fixing hardware (screws, washers, spacers), as a kit for 27.60 GBP. If you fancy one, you can either buy now from here or just message me. Note that the bracket isn't necessary when fitting the PWM kit into a JX-10. Inspired by Guy's switched-mode power supply, I've proposed a couple of joint projects so watch this space! !!! WORDS OF CAUTION !!! These machines are over thirty years old. As such, nuts and screws have seriously bedded in. You may find some glue around the nuts and even some signs of corrosion. If you're upgrading one of these machines yourself, please take care when undoing nuts and screws. The studs which secure the massive heat-sink plate of the original power supply and also the transformer for example, can become lose. When trying to remove the nuts on the inside of the chassis, they'll just spin around and they won't undo. If this happens, you'll need a pair of mole-grips to carefully hold the studs from underneath the case while gently loosening the nuts with a box spanner on the inside of the case. Mole grips can be a little aggressive so you might want to think about protecting the case with some thick tape. Put the tape around the lug of each stud and also put some tape on the tips of the jaws of the mole-grips. I found thick masking tape best for the case and lugs and cloth (or gaffer) tape is good on the mole-grips. When re-assembling, I would recommend replacing the nuts and soaking them in a lubricant like WD-40 prior to fitting. !!! NOT FOR THE FAINT HEARTED !!! The second point I should make is that with the exception of the Vecoven Flash module, all other upgrades mentioned here, require some considerable experience of soldering, desoldering, working with surface-mount devices and respecting electrical safety and electrostatic sensitivity. You should also be prepared to drill into existing PCBs and / or original chassis metal work. !!! Remember, if you get it wrong, you might permanently damage your synth !!! Today, my MKS-70 still looks pretty much as it did when my good friend Rob donated it to me, several months ago. Under the bonnet however, it’s quite a different beast. The sound is still lush and beautiful but... As a result of installing Guy’s P0004 switched-mode power supply, not only has reliability and longevity been increased but this machine can be plugged straight into just about any mains supply on the planet. The sounds can now benefit from pulse-width modulation thanks to the Vecoven PWM upgrade. The Vecoven Super-JX flash module has increased the memory to a ridiculous amount; more patch changes and less SysEx transfers! Firmware updates can now be performed over MIDI. Guy's Super-JX OLED display looks quite simply, beautiful. To the experienced Super-JX user, it might be the only indication that something is err... different. The Super-JX OLED will live much longer than the original VFD and FIP coil which can only give peace-of-mind. LIVE FOREVER BATTERY MOD This is something I do which isn't unique to the Roland MKS-70 and which can be fitted into almost any synthesiser or effects processor. It's NOT literally a 'Live Forever' battery mod as nothing obviously lives forever. The chances are however, that it'll out live you! The damage caused by battery leakage can be irreversible. It's not just a case of losing all those tones and patches that you err... forgot to back up. Battery leakage can seriously damage the PCB on which the battery is mounted; usually the CPU board in most machines. I mount a high-capacity lithium battery off any PCB giving you the following three main benefits: Will last a lot longer than the standard CR2032 which is found in most synthesisers and effects processors. Mounted off-PCB so in the remote event that it does leak, sensitive electronics inside your equipment is protected. Positioned such that battery voltage can be easily checked by only removing the top of your machine. If you missed it earlier, all my prices can be found here. SUPER-JX EDITORS, CONTROLLERS, PROGRAMMERS Anyone with a Super-JX will be aware of the Roland PG-800, a programmer / editor, specifically for the JX-10 and MKS-70. Today, PG-800s are hard to find, relatively expensive and quite honestly, you'd be lucky to find one in really good condition. I'm not talking cosmetically but electronically and it's worth bearing in mind, that parts are becoming ever scarcer. Thankfully, a company called RetroAktiv makes a small collection of hardware programmer / editors for several popular vintage synthesisers... including our beloved Super-JX. I don't have one of these myself but I've heard only good things about the RetroAktiv MPG-70. On top of that... damn, it looks good! At 875 USD, the RetroAktiv MPG-70 costs a couple of hundred USD more than an original Roland PG-800. The thing is, even if you forget about the fact that this box is going to be considerably more reliable than thirty-something year old electronics, you're getting a lot more for your money and (I'm going to say it again) it just looks awesome. If you're still not convinced, then RetroAktiv also makes a smaller Super-JX editor called the MPG-8, which retails for just 349 USD. One of the many features of both of these controllers, is full compatibility with the Vecoven PWM upgrade and firmwares. For some time now, I've been using a plug-in called Ctrlr. It’s basically an open-source environment for Windows, OS X and Linux, which allows users to develop programmers and editors for just about anything. Many users share their ‘panels’ on the Ctrlr website and I was so surprised to find a panel specifically for the Vecoven V.4 firmware upgraded Roland Super-JX. This doesn't really fall into the category of Roland Super-JX upgrades as such but I think it still deserves a mention. Available for Windows and OS X, 32 or 64-bit and in plug-in or stand-alone format, you really need to check this out. Oh and it's free! 😀 The RetroAktiv programmers will work with Super-JXs running standard (factory) firmware although some sliders and knobs won't do anything as there's no PWM to modify, for example. The Ctrlr panel above will ONLY work with Vecoven version 4 firmware. While I've seen Ctrlr panels that'll work with Vecoven version 3 firmware, I haven't come across anything that'll work with bog standard Roland firmware. It's been most reassuring to discover that I'm not alone, that there's a whole community out there that share my appreciation and even passion, for this underrated monster of a synthesiser. I'm so grateful to people like Guy, Fred and the RetroAktiv crew, who after more than thirty years from it's launch, have embraced the potential of the Roland Super-JX, developing upgrades that ensure this magnificent machine lives on. I'd love to contribute what I can so please don't hesitate to contact me if you'd like more information on any of the Roland Super-JX upgrades mentioned here. I'd love to hear from fellow fans of this awesome synth. 😎 In the meantime, here's a few links that you might want to check out: http://super-jx.com/ - Sites like this, truley keep the legend alive! http://www.vintagesynth.com/roland/jx10.php - An excellent reference site. https://www.facebook.com/groups/SuperJX/ - You just knew that there had to be a Facebook group, right? https://www.facebook.com/groups/1837407526336417/ - ...or two!!! UPDATE: 11th July 2020 Wow! Since I put up this post, things have got a little busy.... EL Panel and Inverter Replacement10 May 2020A relatively common problem on older equipment, is the failure of the LCD backlight (or EL-panel). Often accompanied with a very high-frequency whine emanating from the LCD area of the gear in question, it's time to consider an EL panel and inverter replacement. Here's a Roland GC-8 editor / controller for the massive Roland R-880 reverb (circa 1988). Without the controller, the R-880 which really is an awesome machine, is kind of useless as there's little out there to program it via MIDI. Luckily and thanks to a company called backlight4you, LCD backlight replacement is now worth looking into. A variety of EL-panels that are suitable for a whole bunch of older gear, is available at the company's website which is also full of other useful and related information. Their backlights are reasonably priced and arrive from Germany pretty quickly and in very stiff cardboard packaging. After fitting the replacement EL-panel, I powered up the unit to check. Wow! It looks great and on this occasion I got lucky and that bloody annoying whine has gone! IMPORTANT: As a backlight ages, its electrical characteristics change, These changes put a strain on a small circuit called an inverter which converts dc within the unit to high-frequency ac which is required to drive the EL-panel. As parts of this circuit age, it starts to whine. In many cases, replacing the backlight will fix that problem but... not always. : ( If after swapping out your backlight, your unit is still whining, then backlight4you may still be able to help. Take a closer look at their website and you'll find a section on inverters. Designed to run from common voltages and power many of the EL panels that are sold on the website, these replacements are very reasonably priced. Replacement inverters might not be pin-for-pin compatible, especially with very old equipment but with a little ingenuity, you might be able squeeze one in somewhere. Due to the low cost of replacement inverters, I would personally recommend swapping out the inverter if possible, when fitting a new EL-panel. Need help with a hard-to-read LCD? Drop me a line. UPDATE - 20th May 2020 Several days after replacing the EL backlight panel in this Roland GC-8, the high-pitch whine started again. I decided to go back to backlight4you and check out the inverters that are advertised on the company's website. Due to the limited space inside the GC-8, I needed something small and indeed the backlight4you inverters do look as small as you can get them. While waiting for the inverter to arrive, I removed the original transformer from the GC-8 inverter circuit. This is the component that actually generates the whine. When the inverter did turn up, it was quite obvious that it wouldn't fit straight on to the GC-8's PCB. I expected as much but I'm stating this for clarity to others. I ended up placing the inverter, underneath the main PCB towards the sockets at the back of the GC-8. Phew! It just fitted. The slanted profile of the unit meant that it wouldn't fit towards the front where there's a bit more room. Typical!!! Connecting the 3-terminal device was straight-forward and since my GC-8 isn't going on an interplanetary mission in the near future, securing it just needed a little double-sided tape and hot glue. It's important to note that this little black epoxy resin box, is a complete inverter and NOT just the transformer. Time to power up and test. DEAD quiet! Wow, this is definitely worth doing. I actually have two Roland R-880s and so, two GC-8s. My EL panel and inverter replacement on one of my units, meant that well, I just had to do the other one, too! 🙂... Roland MKS-70 Power Supply Replacement2 May 2020Never thought I’d make a new friend over lock-down but I have recently struck up a relationship with Guy Wilkinson of supersynthprojects.com. While working on a very broken Roland MKS-70 that I have in for repair, I came up with the idea to design a MKS-70 power supply replacement but figured that after all these years, perhaps someone has already thought of this. After a few minutes of searching on-line, I stumbled across https://supersynthprojects.com. The work that Guy has done, is truly amazing. His power supply design is quite simply, elegant and I’m so impressed with his methodical record keeping. As it turns out, Guy seems to be a bit of an expert on several vintage machines. Anyway, having a Roland MKS-70 myself, one thing led to another and I’m currently in the process of building one of Guy’s P0004 switched-mode power supplies and installing his Super-JX OLED display module into my own MKS-70. It’s a bit difficult doing this during lock-down but I’ll keep you posted of progress. Guy sells the P0004 switched-mode power supply bare PCB and the pre-assembled Super-JX OLED display directly but you'll need some competence to populate the former and fit either, into a JX-10 or MKS-70. If you're cool enough to admit that all of that sounds a bit too much for you, then please don't hesitate to contact me to discuss getting either (or both) fitted into your machine. Click here for prices. If you're fitting the switched-mode power supply module yourself and your MKS-70 or JX-10 has a 2-pin IEC mains input socket, then you must replace it with a 3-pin IEC mains input socket. The replacement switched-mode power supply MUST be connected to earth as must the chassis of your Super-JX. I offer a comprehensive earth bonding kit comprising the following: 1 x IEC 3-pin chassis socket. 3 x pre-cut heat-shrink strips. 1 x insulating boot for IEC socket. 1 x M3 earth tag. It is paramount that if fitted, a 2-pin IEC mains socket be replaced with a 3-pin IEC mains socket and that the chassis and the P0004 are connected to earth.UPDATE - 10th MAY 2020 Last night I installed the assembled switched-mode power supply into my own Roland MKS-70. I'd already tested it outside the machine but I was still nervous. Hey, the MKS-70 fired up straight-away. The power supply worked just fine and quite honestly, if you're having issues with the power supply in your Roland MKS-70 or JX-10, then getting one of these is a no-brainer! UPDATE - 12th MAY 2020 Took a while and was a bit tricky but the display got done and works absolutely brilliantly (pardon the pun). In fact it looks positively beautiful. The Super-JX OLED module 'learns' the system's firmware so before I switched on the unit to test, I thought I'd drop in the Vecoven Super-JX flash module. Pressed the power button and everything powered up just great. UPDATE - 19th MAY 2020 Several days ago, I posted here that I'd keep you updated of progress on this project. I also suggested that I'd probably end up making a new post. Guess what? So, click here for more on Roland Super-JX Upgrades. ... Roland MKS-70 Repair19 March 2020Recently, this gorgeous vintage Roland MKS-70 synth module came in for repair. The MKS-70 is basically the rack version of the Roland JX-10 keyboard synthesiser, which itself is essentially two JX-8Ps. Also known as the Super-JX, the JX-10 and the MKS-70 are famous even today for their rich, analogue tone and pristine sound quality. At this point I need to make something clear; the Super-JX is not actually 100% analogue unlike for example, one of it's well known predecessors, the MKS-80. The oscillators are in-fact, digital. So when I refer to 'analogue' tone, I'm referring to just that, the tone. Check out more details and some sounds here and here. Anyway, the customer said that it wasn't powering up properly with just a flash briefly appearing on the display and then nothing. Well, let's see if we can get this ol' girl singing again.. Apart from being a giant classic, the MKS-70 like the MKS-80, has hinged circuit boards which means that it opens up quite nicely. Having said that, if you need to get at the 'CPU' board (the service notes refer to this as the Assigner board, for some reason), you really do need to disconnect and remove the lower analogue voice board. Checking voltages before anything else, I realised very quickly that I had a major problem. The voltages on the power supply were all about 25% more than what they should be. Eek! Hope no serious damage has been done. I'll keep you posted on this fix but please bear in mind that I'm respecting the COVID-19 lock-down so it may be a while before I'm back. UPDATE - 2nd April 2020 The power supply is a really clever and well thought out design for the time but I don't think the Roland R & D team had any idea that their machines would still be making music over thirty years after their conception. There's a small voltage monitor chip on the power supply which, when it fails, sends the +/-15 V rails to like +/-22 V. Unfortunately the +5 V rail for the digital stuff has a dependency on the +15 V rail so if that freaks out, then so does the +5 V supply. I decided to change all the major components on the PSU including transistors, capacitors, bridge rectifiers and of course that frigin' voltage controller IC. Okay, so now power is good. UPDATE - 14th April 2020 Well the voice-boards turned out to be fine but the CPU or assigner-board, was seriously not happy. The code was trying to run but not getting anywhere. My worst fears an' all that... This was not going to be a straight-forward Roland MKS-70 repair! I'll get back as soon as I get somewhere... or not 🙁 UPDATE - 14th January 2021 The assigner board on this Roland MKS-70 is indeed kaput. Having got to know Guy Wilkinson of SuperSynthProjects over lock-down, Guy came over when things calmed down and we both agreed that although laborious, one coarse of action would be to swap out all of the ICs but... as many will know, there's one IC that can't be replaced and that's IC2, the 63H149 gate array. The Roland 63H149 is used in a lot of Roland keyboards and modules, right up to the S-10 and the D-50. In many machines, including the keyboard version of the MKS-70, the JX-10 the 63H149 is mainly used as the keyboard scanner but unfortunately, it's also quite connected to other devices in the MKS-70. Guy came up with an idea and is currently in the process of designing a 'replacement' for the 63H149. This isn't going to be a drop-in 80-pin device like the 62H149 itself but something that will kind of 'bypass' the chip's functions and fool the MKS-70 into thinking that the gate array is there and functioning normally. If we can do this, it'll be quite a break-through and will potentially save a lot of MKS-70s. An exciting but time-consuming project, it's going to take a while but be sure that I'll definitely keep you posted. Please don't hesitate to contact me if you have a sick Roland MKS-70 or any other vintage synth.... Plasma Music Sale 202018 March 2020Last year, I started to downsize my recording facility and so a lot of stuff is now up for grabs in my Plasma Music Sale 2020. It's not just studio gear but drums, cymbals, guitar and keyboard stuff, video cameras, computer equipment and live performance gear like complete PA systems, mixing desks, powered monitors, multi-track recorders, amps, radio mics and so much more. Some of it's old and some of it is relatively new but either way, it's all been lovingly looked after while I've had it and most of the stuff is in pristine condition and it all works perfectly. Please do check it all out my Plasma Music Sale 2020 here before it all goes on eBay! If you need more information about a specific item or just not sure about something, then please don't hesitate to contact me.... OK Google Switch On My Computer1 March 2020JUST SAY "OK GOOGLE SWITCH ON MY COMPUTER" TO TURN ON YOUR COMPUTER VIA GOOGLE ASSISTANT. NO MESSING AROUND WITH LOADS OF APPS NO CUT AND PASTE COMMANDS JUST SET THIS UP AS A DEVICE IN GOOGLE HOME OR AMAZON ALEXA My Smart Momentary Switch, or SMS, allows you to switch on your computer via Google Assistant or Alexa, with a simple command like "OK Google, switch on my computer" or "Alexa, switch on my computer". If your computer is called 'Dave', then telling Google or Alexa to switch on Dave will also work! 😀 SMS is basically a kit comprising a small plastic box which houses the radio transceiver to connect to your WiFi and a PCI back-plate which fits inside your computer and connects to your computer's motherboard. The external enclosure is USB powered and a USB power adapter (UK 3-pin) and integral USB cable are included. The box connects to the PCI back-plate via a cable which has 3.5mm jack plugs at both ends. With easy-to-follow and fully illustrated installation and set-up instructions, SMS can be up and running in minutes. Please do however, note the follow restrictions: SMS is ONLY suitable for computers that have an accessible motherboard and a standard motherboard header. UNFORTUNATELY, SMS IS NOT SUITABLE FOR LAPTOPS, TABLET PCs, STICK PCs AND MACs. Since parts need to be attached to your computer's motherboard, a basic proficiency of working with computer hardware is required. If you're not confident to open up your computer and move a couple of bits around, then do find a friend who is, to help you. OK GOOGLE, OPEN MY GARAGE DOOR Yes, that's right! I make a version of this gadget which can be used to open and close your electric garage door via your Smart Home (Google Home Assistant or Amazon Alexa). So how much does it cost? £58.80 plus postage (almost anywhere). That's a bit more than I'd like but I hand make these myself in small batches. Click here to buy.... Behringer DEQ2496 Repair26 February 2020On the bench today is a Behringer DEQ2496 repair. This is the third generation of 'Ultra-Curve' from the well-known German manufacturer. The DEQ8020 and DEQ8024 were both 2U units but in 2005, Behringer released the super high-specification 1U DEQ2496. These extremely high-quality and versatile processors do a lot more than graphic equalisation. Amongst the machine's function is a real time spectrum analyser. You can purchase a Behringer ECM8000 calibration microphone and quickly and easily set up the graphic to 'compensate' for room acoustics, for example. There's also a mired of other functions such as parametric eq, dynamic eq, dynamic processing and time delay, to name but a few. With digital inputs and outputs (S/P DIF on TOSLINK and AES / EBU), the analogue side of the DEQ2496 is balanced and boasts a fantastic dynamic range with its 24-bit / 96 kHz conversion. Finding popularity amongst hi-fi enthusiasts and audiofiles, the latest and current Ultra-Curve is of course also very popular with PA hire companies, recording studios and even in musicians' instrument rigs. So, unreliable power supply, then? No, definitely not! The date code on the one that's on the bench today is July 2006. That makes in almost fourteen years old and quite honestly, it's done bloody well, in my humble opinion. The repair to the power supply takes just over an hour. The parts cost about twenty quid and in no time, the machine's going to last another fourteen years, at least. 🙂 So, if you're in need of a Behringer DEQ2496 repair, don't hesitate to give me a call. Check out the Behringer DEQ2496 Ultra-Curve here.... Unbalanced to Balanced Converter17 February 2020Many musicians, engineers and producers appreciate why signals should be kept as 'hot' as possible. High signal levels can reduce your noise floor and of course a lot of professional, studio equipment is designed to run at +4dBu (about 1.25 volts). What many might not appreciate is the virtue of also running balanced signal lines. My unbalanced to balanced converter Transformer Coupled Interface (or TCI) does just that. It converts a +4dBu unbalanced signal to a +4dBu balanced signal (no gain). Running an analogue audio signal over a balanced line severely increases immunity to noise. I won't go into the physics of just why that is yet, although I'll no doubt end up adding to this post at some time in the future. Unfortunately there's a lot of older gear out there including stuff we all love dearly, which has unbalanced +4dBu outputs. The Marshall JMP-1 that was featured in a recent post, is a prime example. The Roland RSP-550, an excellent nineties multi-effects processor, is another example. So, the traditional way to convert an unbalanced signal to a balanced signal is to run it into a D.I. box. We're all familiar with those little boxes that cover many a studio and stage floor, right? They work just great but while they balance the signal, they also knock down the level of the signal to a few millivolts which means that you have no option other than to run the other end into a mic. pre-amp, either as a separate unit or built into a desk. That's not always convenient and it seems stupid attenuating a signal, only to amplify it again, anyway! Have you noticed another downside to trying to use a D.I. box to solve this problem, yet? Earlier I gave the example of the Roland RSP-550. It's an effects unit. It has +4dBu inputs! So you ain't easily gonna be able to send signal from your desk to it via a D.I. box! The inputs on the RSP-550 are looking for either -20dBV or +4dBu. The microphone level output from a D.I. box just won't be enough to drive the unit. On top of that, the D.I. box output is balanced. The inputs on the RSP-550 are unbalanced. That's actually two downsides. 🙁 To convert an unbalanced signal to a balanced signal and maintain the level of the original signal was a problem I decided to solve once and for all, many years ago. I developed the transformer coupled interface (TCI). It's not rocket science (as they say) but boy, do these things come in handy. The TCI is a non-powered device (like a passive D.I. box) which basically comprises a single transformer on each channel. For an unbalanced to balanced converter, that's all you need, really. Having said that, you of course, want the highest quality transformer you can get. You need a good frequency response but also, good phase coherency. Phase distortion, especially down the bottom end, is characteristic of cheaper transformers and if not addressed, makes bass guitar for example, sound woolly. Similar to a passive D.I. box, one hidden benefit to using the TCI, is that it offers something called galvanic isolation which means that there is no physical connection like a piece of wire for example, between between your source and destination equipment. With the ability to easily lift the earth of the source equipment, the TCI Type 1 is just great for helping to get rid of ground loop problems! IMPEDANCE All equipment has what’s called an input impedance and an output impedance. Impedance, like resistance is measured in Ohms but differs in that it's frequency dependant. Impedance varies with frequency and so the impedance at say 500Hz will be different to the impedance at 5kHz. Having said that, due to the nature of things, a common resistor is often used on for example, the output of an electronic circuit to provide the output impedance of a system. Most guitarists will be quite aware that everything to do with guitar electronics is high impedance and that the first thing you plug your guitar into should have a very high input impedance. This reduces the ‘loading’ on the guitar pick-ups and allows for a good frequency response further on down the chain. Unbalanced outputs like those found on a lot of consumer electronics such as hi-fi gear, have a high impedance, perhaps in the order of thousands of Ohms. Balanced outputs in contrast, are always low impedance; just a couple of hundred Ohms. Again, I won't go into the physics suffice to say that this is why amongst other things, low impedance outputs allow for long cable runs. There are exceptions however and while unbalanced, a lot of studio gear has low impedance outputs. This makes life a lot easier! The TCI is classed as a low input impedance device and while it will technically work on something with a high output impedance, you might notice some high-end roll-off. Basically, you’ll need to check the output impedance of your gear before considering a solution like the transformer coupled interface. That’s why D.I. boxes are so popular. D.I. boxes have a high input impedance which means you can plug in just about anything. Like my transformer coupled interface, passive D.I. boxes also have a transformer to convert the input to a balanced line. The turns ratio of the transformer however, is such that while presenting a high impedance at the input and low impedance at the output, the signal voltage is greatly attenuated. Hence, the output of D.I boxes is mic. level. Housed in an aluminium enclosure, TCI's transformers are individually contained in MU-metal cans, all of which contributes to very high noise immunity. So, if you've got problems interfacing some of your gear with your mixing desk or DAW and you reckon that an unbalanced to balanced converter might help, please don't hesitate to contact me. UPDATE - 22nd June 2021 Weeks after launching this post, I received so many inquiries about my TCI, that I decided to make a production version. I'm pleased to announce that this amazing little problem solver is now available to buy. Like all my stuff, TCI is designed and made by me, here in Hemel Hempstead, UK. I do however, use sub-contractors for making enclosures, PCBs, etc. Unlike many, I only use local companies and here's why... I'm deeply concerned about the environment and the exploitation of labour and so I always use local manufacturers in preference to the Far East, with the following in mind: I can be confident that workers are treated fairly and earn a proper wage. I can be confident of the standard of quality of each item that is delivered to me. Communication is important and using local manufacturers, all correspondence is quick and understandable. I believe in supporting the local economy. I can be confident that the disposal of manufacturing waste is managed properly and in accordance with national and EU law. Using local manufacturers isn’t the cheapest option but the above points are important to me. I hope that they’re important to you too.... Marshall JMP-1 Service13 February 2020Here’s a Marshall JMP-1 MIDI valve pre-amp that I’ve just serviced. I’ve changed the valves and power supply capacitors, cleaned up the metal work and implemented my ‘Live-Forever’ battery mod’. The original battery is mounted bang in the middle of the main PCB, so you really don't want this to leak. The serial number indicates that it was built in early 1992 which not only makes it twenty-eight years old but one of the first JMP-1s off the Marshall production line. An early MIDI valve pre-amp although following the likes of similar pre-amps like the ADA MP-1, the Marshall JMP-1 has always been a really under rated bit of kit, despite the fact that named artists such as Billy Gibbons (ZZ Top), Phil Collen (Def Leppard), Iron Maiden, Megadeth and many more, still use them even today. In production for well over ten years, also says something about this little gem. The JMP-1 is not a modeler like modern stuff; it’s the real thing, just with MIDI. Run into a valve power amp (or two), it just sounds amazing and the quality of the speaker emulated outputs is definitely good enough to go straight into the board or your DAW. With most of the distortion being generated in the semi-conductor domain (some of which is highlighted in the image below), many purists might shy away from this beast. On the other hand, classic Marshalls such as the legendary Silver Jubilee series and the monstrous JCM900 Dual Reverb, also use semiconductors to produce some of their distortion tones. And then there's the clean channel of the JMP-1 which is based on the classic Fender design... with a few tweaks, of course. Anyway, at the end of the day, it's the sound that counts and as I've said, these things have still got it, even today. RATTLE A' HUM Lots of JMP-1s hum. This doesn't come through the audio outputs but it can be annoying and I've been trying to get to the bottom the cause for years. Now, instead of looking at the JMP-1, I'm going to look at what the JMP-1 is plugged into… We all know that mains voltage is AC (alternating current). The voltage varies between 100V and 240V depending on where you are in the world. The frequency also varies and can be either 50Hz or 60Hz. We convert this AC voltage to DC (direct current) to power appliances, gadgets and other systems that now dominate our lives. So why is the supply AC and not DC, then? Well, the answer to that is a little involved as there isn’t a single reason. Predominantly however, it’s a matter of safety. If you are in contact with a mains supply (eek), the alternating nature and the frequency of the supply gives the human body enough time to react and pull away. There are other reasons to do with energy but safety is the main reason that the electricity supply is AC. Unfortunately, it’s not pure AC, though. There’s a DC element present in the mains which has actually grown over the past twenty years or so due to the fact that the number of appliances that use what’s known as half-wave rectification has increased. I won’t go into just why half-wave rectification dumps DC on the mains suffice to say that it can be an issue for some devices. “So how does that affect my Marshall JMP-1?” I hear you ask. Well, the other downer is that some appliances contain components that are particularly sensitive to the DC offset on the mains supply and it just so happens that the transformer in the Marshall JMP-1 is one of them. 🙁 Anyone with a little electrical know-how will now wonder how that can be. Transformers are inductive components and so filter out DC. Yep, that’s absolutely correct and in fact the DC that’s on the mains doesn’t get through to the rest of the power supply in the JMP-1. What the DC component can do however, is saturate the core of the transformer, thus causing the laminates to oscillate. The gap between the top of the transformer and the inside of the JMP-1's top case is very small so you can guess what happens. That's why the hum disappears when you remove the top-case! What pointed me in this direction was that after being on for about an hour or so, the laminates on the transformer get seriously hot. I mean SERIOUSLY hot. The JMP-1’s regulators however, don't. In fact, they don’t even have any additional heatsinking. This paradox was intriguing. I concluded that the transformer heats up as a result of oscillation. As mentioned, the heat is substantial and the transformer is heavily stressed as a result. Over time, this will reduce the life of the transformer. I'm afraid it's just a matter of time before the transformer fails. 🙁 I should mention the obvious; the JMP-1 has got a couple of valves in it! Although running at about 300V, much higher voltage than the semiconductor parts of the analogue circuitry, they consume very little current and hence, the supply for the valves isn’t regulated. The valve heaters run at about 6.3V and although they ‘heat’ (obviously), it’s not normal to regulate the supply to the heaters, either. Familiar with DC offset on mains being a problem on high-end audiophile equipment, all the evidence seemed to be mounting up. 🙁 You can suppress the hum with cushioning between the top of the transformer and the case but this will only keep the transformer from dissipating heat that's generated as a result of the problem and hey, it doesn't actually fix things, does it? If asymmetrical voltage supply is indeed the problem, then the only real and proper solution is to get rid of the DC component all together. I'm pretty determined to get to the rout cause of this and will keep everyone posted on how my pursuit for the quiet Marshall JMP-1 progresses. UPDATE - 4th January 2021 If you want to read more, my latest Marshall JMP-1 post is here. I now provide replacement Marshall JMP-1 Knobs Nuts and Bezels sets which you can read about here. I've also developed something called Eclipse; a bounce eliminator which can be fitted by anyone with a little technical know-how and which gets rid of the data entry knob skipping thing! You can read about Eclipse here. UPDATE - 13th March 2021 A thousand apologies, Plasma People! What with the flood back in August and COVID-19, I've been a bit distracted! 🙁 Anyway, on the back of my theory that the transformer in the Marshall JMP-1 may be susceptible to mains DC off-set, I designed Orion Type A, a DC filter / blocker. Orion worked very well and indeed does filter out DC on the mains but... I'm afraid it didn't get rid of the hum on the JMP-1. THERE'S STILL LIGHT AT THE END OF THE TUNNEL A few months ago, I managed to track down a chap called Graham Sopp. Graham has a company, the name of which may be familiar to some. It's called Dagnall Electronics. The reason for potential familiarity is that many of you will recognise it as being that on the side (or top) of many a Marshall transformer! That includes our beloved JMP-1's power transformer. Well, Graham wasn't just exceedingly knowledgeable but was also very (VERY) helpful. We had some considerable correspondence over e-mails and he expressed his surprise at my theory of DC off-set being the reason behind our humming JMP-1 transformer, suffice to say his scepticism was well founded. Anyway, Graham's suggested that I conduct a few tests and get back to him with my findings. He said there are two potential paths to follow; the first is that I return humming transformers which will have their laminations replaced and will then be re-varnished. The second is that 'we' design a new transformer using a higher specification material for the laminates. Dagnall Electronics is a design company and does not manufacture anything. The company that actually makes the transformers, is called TRX Electronics and is based in Malta. TRX Electronics is no longer set up to manufacturer the TXMA-00014, the original JMP-1 transformer. This means that developing a TXMA-00014 Mk II (?) could be quite expensive, if TRX Electronics even considers taking on the job. On the other hand, it would be quite impactable for JMP-1 users, me and TRX Electronics, to send potentially single transformers back and forth. As I said, I really am on a mission to resolve this but please be patient. Drop in here every once in a while and I'll get back to you as soon as... UPDATE - 22nd June 2021 While the outputs of the Marshall JMP-1 are +4dBm line-level, they're also unbalanced, which was quite a common feature (or lack of) for the time. I spent quite a while, looking to install balanced output drivers into the JMP-1 but changing the 2-pole sockets over to 3-pole, was a major obstacle for my plans . Today however, I released my Transformer Coupled Interface (TCI) Type 1 which is a passive stereo unbalanced to balanced line-level converter. TCI allows you to properly interface your favourite MIDI valve guitar pre-amp with your DAW or mixing desk. You'll notice the difference! 🙂 Read more about my TCI Type 1 here. Marshall JMP-1s now go for between £400 and £700 (yes, £700). If you can pick one up nearer £400, then I personally think you've got yourself a bargain and a seriously good bit of gear. If you want to find out more about the JMP-1, then there's loads of resources on-line and of course there are Marshall JMP-1 groups on Facebook like this one: https://www.facebook.com/themarshalljmp1 I know this box inside-out and I absolutely love it and love working on them, so if you have a JMP-1 that's in need of a little TLC, then don't hesitate to contact me. MARSHALL JMP-1 FACTORY RESET WARNING: Implementing this procedure will permanently delete all user-made changes to any patches. If you want to save your JMP-1's memory, do a MIDI dump first. Switch off JMP-1 via the power button on the far right. Hold down the OD1 button and the CLEAN 1 button. While holding down these buttons, switch on the JMP-1. Wait a few seconds while the display flashes and then release the OD1 and CLEAN 1 buttons.... Audio Triggered Power Switch11 February 2020Over the past couple of weeks, I’ve been designing an audio triggered power switch; a gadget to switch on a power amp when an audio signal is detected and to wait a few minutes to switch off the power amp when no signal is present on the input. The audio signal comes straight from the sub bass output of an A/V receiver amp and is therefore about -10dBV (approximately 310 mV) unbalanced. So apart from auto switch-on / switch-off, the circuit also amplifies the input signal to +4dBu (about 1.25 V) balanced which is whet the power amp wants to see on its inputs. After testing a prototype for several months, this evening I ordered the PCB (the design of which is pictured above) for the final version. SO WHAT'S THIS ACTUALLY USED FOR? Well, the power amp in question, drives a sub-bass system on a home cinema. It's a big, professional amp and definitely wouldn't come with auto power-on / power-off or standby, which of course, the main (consumer) A/V receiver amp does have and which 99.9% of consumer sub-bass units have built-in. The idea is that when the home cinema system is switched on, the power amp comes on when it detects a signal. When the system is switched off, the power amp switches off a few minutes later... PERFECT! I wanted a minimal signal path for the audio that's being sent from the A/V receiver to the power amp, with just a little gain (-10dBm to +4dBm) and unbalanced to balanced conversion and I also wanted bags of headroom so the whole thing runs at +/-15V. CREDITS I don't see the point of reinventing the wheel, especially if someone has already designed something really good that works. Hence, the switching circuitry of this gadget is based on a design by Rod Elliot of Elliot Sound Products (see project 38). Rod puts up some fantastic, in-depth explanation into how the circuit works and how it can be tweaked to your specific requirements. UPDATE - 18th February 2020 This morning, my PCBs arrived. I couldn't wait and quickly got down to populating one of them ready to test later in the afternoon. Well, I'm pleased to report that all worked well. With a 1kHz sine wave, the sensitivity of the circuit is about 4.5mV and the delay to switch-off time is about ten minutes. Unfortunately, the case I'll be using for this, is currently out of stock 'till 17th March, so it looks like this is going to sit on the shelf for a few weeks 🙁 UPDATE - 18th March 2020 Today I went over to RS Components in Watford to collect the enclosure that I'd planned to use for this project and the dimensions of which were part of the design of the PCB. Well, I couldn't believe what I was told; the boxes remain on back-order 'till, wait for it... 31st July. Seriously?!?!? I checked last night and there was no change in status. What the hell are you playing at?... Roland VK-7 Power Supply Rebuild4 December 2019This Roland VK-7 power supply rebuild started with my friend, Alex Richards bringing me his broken machine. The transformer is mounted upside-down on the inside of the top chassis. Guess what? It fell off! The machine was plugged in at the time so the accident caused considerable damage but luckily no one was injured. To avoid this happening again, I mounted this heavy little component to the bottom (steel) chassis and laid new connections to the power supply board. Mounting the transformer to the chassis required some hole drilling but at least the transformer was undamaged. I don't think I would have been able to source a replacement if it wasn't. Twenty years old, has taken quite a few knocks but it plays and sounds great. Check out more on the Roland VK-7 here. If you have one of these and there's no power, perhaps you can hear or feel something loose inside, then contact me for a Roland VK-7 power supply rebuild.... Nektar Impact – Best Tech Support Ever4 December 2019Customers’ units come first so when my own stuff needs repairing, it kind of gets put to the back of the que, especially if it’s not a critical system. Anyway, a few weeks ago, the attack slider on my Nektar Impact LX61+ MIDI keyboard started playing up. I tried to do a quick fix but the potentiometer was definitely duff. I fired up a support ticket and received the most amazing response from Nektar. The company basically just sent me a whole new PCB! All I really wanted was the slider pot’. Cost-effective, versatile and easy to program, the Nektar Imact range of MIDI controllers seems perfect for any project studio set-up. Now that I’ve experienced the company’s support first-had, I really can’t recommend them enough. Check 'em out yourself: https://nektartech.com/ Mine’s a 61-note which means it’s only got USB out. With a USB switch though, I can run it into my DAW or to a USB MIDI host which allows me to drive my MIDI synths.... Marshall Mondays7 October 2019Of course I don't just do Marshall repairs on Mondays but what a great way to start the week; a gorgeous 4502 JCM900 50W Dual Channel Reverb on the bench. There's nothing too wrong with this amp. It just came in for a re-valve and a tune-up (bias check) after the customer complained that it sounded a bit dull and lifeless. In my humble opinion, the JCM900 Dual Channel Reverb was the last 'proper' Marshall. Personally I'm a 100W head freak but the 50W heads and combos do sound sweeter. Put a 50W through a 4 x 12 and you get a whole lotta' beef underneath that sweetness. HEAR AND FEEL THE DIFFERENCE I ALWAYS USE PREMIUM MATCHED VALVES AND I ALWAYS RE-BIAS CONTACT ME I get a lot of people ask me about impedance matching valve amps and speaker cabs so sometime over the next couple of weeks, I'll be posting some bumf on how it all works and best practices. Stay tuned! UPDATE - 12th June 2020: A little more than a couple of weeks 🙁 but here's my post on guitar amp and cab impedance matching.... Cool Stuff – The Yamaha GPI5 October 2019Virtually all high-end Yamaha mixing desks such as the DM series, PM5D, LS9 and CL / QL series to name but a few, are equipped with the Yamaha General Purpose Interface or GPI. The picture above shows the GPI buttons under the 'User Defined Keys' section on a Yamaha DM2000. It's a great idea and can be so incredibly useful in so many situations. Unfortunately, very few people know what GPI is all about and Yamaha only offer limited implementation options. Often used to interface a desk with video equipment, the Yamaha GPI standard can also be used to switch on and switch off other equipment such as amplifiers, computers and outboard gear which might be located some distance from the mixing desk. For recording and live applications, this facility could be so incredibly useful. To take advantage of the Yamaha general purpose interface, I build a distribution box and various gadgets which will allow the GPI on your Yamaha mixing desk, to do just that. Pictured below is a 3-channel mains power switcher in a solid steel case, capable of switching three loads totalling 10 amps. This particular interface switches three power amps located in another room in a recording studio. Also pictured, is the breakout box which splits the GPI from the desk to eight individual lines. Channels 7 and 8 of this particular switch for example, are used to switch on two computers, also directly from the desk. If you have a Yamaha mixing desk equipped with GPI and want to remotely switch gear on and off from it, then don't hesitate to get in touch.... RME Fireface 800 Repair4 October 2019On the bench today; a RME Fireface 800 with a faulty power supply. Many will know that I'm a mega-big RME fan. Stylish, reliable, oozing sonic excellence in abundance and very easy to use, RME interfaces like the Fireface 800 are sonically very transparent. When it comes to drivers and firmware, RME is constantly on the ball and software issues with their products simply don't exist. A bold statement I know but in my experience, it's true! Anyway, every six or seven years the power supplies on these systems pack up. Delivering a reliable but significant output, they do get hot and despite the use of high-temperature tolerant components, time takes its toll. Symptoms range from flashing lights on the front panel, to the unit not powering up at all. IMPORTANT!!! If you do get the flashing lights but the unit appears to work okay, please, please, please don't wait until it totally dies, to get it fixed. If you do, you'll probably need a completely new power supply... if you're lucky. If you're unlucky, you're Fireface 800 might need major surgery. 🙁 So, if you're in need of a RME Fireface 800 repair, then I'll be more than happy to help you out. It's well worth it. These interfaces are just great. I charge a standard £85.00 for a power supply repair. Just contact me if you want to chat. Click here for more information on RME interfaces. In the meantime, here's the spec': Input AD: 8 x 1/4" TRS, 4 x XLR Mic, 4 x 1/4" TRS Line, all servo-balanced. 1 x 1/4" TS unbalanced Output DA: 8 x 1/4" TRS, servo-balanced, DC-coupled signal path. 1 x 1/4" TRS unbalanced Input Digital: 2 x ADAT optical or SPDIF optical, SPDIF coaxial (AES/EBU compatible) Output Digital: 2 x ADAT optical or SPDIF optical, SPDIF coaxial (AES/EBU compatible) MIDI: 1 x MIDI I/O via 5-pin DIN jacks, for 16 channels low jitter hi-speed MIDI Dynamic range AD: 109 dB RMS unweighted, 112 dBA THD AD: < -110 dB (< 0.00032 %) THD+N AD: < -104 dB (< 0.00063 %) Crosstalk AD: > 110 dB Dynamic range DA: 116 dB RMS unweighted, 119 dBA (unmuted) THD DA: < -103 dB (< 0.0007 %) THD+N DA: < -100 dB (< 0.001 %) Crosstalk DA: > 110 dB Input/Output level for 0 dBFS @ Hi Gain: +19 dBu Input/Output level for 0 dBFS @ +4 dBu: +13 dBu Input/Output level for 0 dBFS @ -10 dBV: +2 dBV Sample rate internally: 32, 44.1, 48, 64, 88.2 kHz, 96 kHz, 128, 176.4, 192 kHz Sample rate externally: 28 kHz - 200 kHz Frequency response AD/DA: -0.1 dB: 5 Hz - 21.5 kHz (sf 48 kHz) Frequency response AD/DA: -0.5 dB: < 5 Hz - 43.5 kHz (sf 96 kHz) Frequency response AD/DA: -1 dB: < 5 Hz - 70 kHz (sf 192 kHz) UPDATE - 11th March 2021 I regularly receive inquiries about the RME Fireface 800 and have been toiling with the idea to make an external power supply. I've tested a couple of my designs which power the Fireface really well. My designs don't get hot and will last much longer than the original. The problem is that they're all external! So, there are a few problems to overcome... You need to get a 6-pole connection reliably into the chassis of the unit. The obvious place to do this, is in the position of the IEC power inlet. The problem is that the power inlet is a snap-in type so there are no screw holes. Synthax UK have kindly offered me an old demo unit to play with but I need to be confident that what I do, can be also done by end-users. As I said, my replacement power supply works just great so that's a good start. I'll keep you posted on how this project progresses....
