News Check out all the latest news here on my 'News' page. Got any questions? Then just contact me. 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 Power Supply for the Roland MKS-8017 July 2020>>> NOW AVAILABLE <<< Aurora - a modern switched-mode replacement power supply for the Roland MKS-80. The Roland MKS-80 is an amazing piece of equipment and 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 I still have an installation manual to produce but in the meantime, here's a few things to consider... 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 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. Aurora Replacement Power Supply for the Roland MKS-80 is MADE IN THE UNITED KINGDOM 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 Prices page. Just scroll down 'till you get to Aurora.... 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 only upside-down, relative to itself. 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. If the amplitude of both sets of outs is the same, you’ll get nothing if for example, when you mix the two together. 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. Like my MKS-70 rack-ears, these are made from aluminium with a back anodised finish on top of a horizontally running mill finish (just like the originals) and of course, they fit perfectly. They'll be supplied with eight black countersunk M4 machine screws. I'm now happy to announce that these rack ear kits are available to purchase. You can either check out my Prices page here, or just Buy Now. Don't hesitate to contact me if you need more details on RE-MKS-80 rack ears for your Roland MKS-80. IMPORTANT: Shipping price is for UK mainland only. If you're an international buyer, I'll send you an e-mail stating the difference to pay to ship to your country / region. And finally, a BIG "thank you" to Lenton Engineering in Watford for delivering another precision job. MADE IN THE UNITED KINGDOM 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 Made from aluminium with a black anodised finish on top of a horizontally running mill finish (just like the originals), these rack ears will be supplied with eight black M4 countersunk machine screws. I'm now happy to announce that these are available to purchase. You can either check out my Prices page here or just Buy Now If you want more details on my RE-MKS-70 kit, then please just contact me. 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. MADE IN THE UNITED KINGDOM 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. 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 (also referred to as AC/DC converters) 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 converter 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. 🙂 Of course, there’s a down-side to switched-mode power supplies. The regulator in a linear supply is replaced with a ‘switching’ regulator in a switched-mode power supply. The switching happens at several thousand times per second and generates considerable noise and so for audio applications, the output needs to be cleaned up. This is normally done using a filter network comprising passive components such as inductors, capacitors and resistors. The maths to achieve proper filtering can be quite involved but… it doesn’t stop there. Careful attention has to be given to the physical layout of the printed circuit board (PCB) as tracking for example, can act as a pick-up or aerial and a lot of that maths previously used to design that all-important filter stage, could go to waste if some rules aren't observed at the PCB design stage. Relative proximity of components must also be considered carefully. When space is at a premium, this last aspect of switched-mode power supply design is particularly challenging. 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 280 mm x 210 mm. 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 fixing 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 +15 V supplies are on one connector, all the -15 V 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 10 V 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 0.9 W. With on-board 5 V regulators, that means that the current drawn is about 180 mA. The 10 V reference source is just that, a reference and so current requirement isn't an issue. That means we're left with +/-15 V for the voice boards and +5 V 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 25 W converters for the +/-15 V rails and a 15 W converter for +5 V 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 Vigortronix's 9 V version of the 2 W converter which will deliver 222 mA. The 9 V supply is being sent outside of the MKS-80, so Roland decided to protect it with a 125 mA 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 +5 V and +15 V 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: +5 V line measured in at +5.01 V (10 mV ∼ 0.2%.) +15 V line measured in at +15.08 V (80 mV ∼ 0.53%). -15 V line measured in at -15.10 V (100 mV ∼ 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 carefully studied the service notes. I looked over the schematics many, many times. I just couldn't find any reason for the high level of accuracy for the +5 V and +15 V rails and yet the accuracy for the -15 V line was pretty average. The CPU-board should work fine on a little less than (bang-on) 5 V. In fact slightly lower would be better. Although the 10 V reference voltage is initially derived from the +15 V rail, the circuit that generates it, wouldn't require the high degree of accuracy specified. 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. All voltages good with +15.00 V, -15.07 V, +4.97 V and +9.01 V 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. This means that Aurora is finally good to go. My official post on Aurora is here and you can now 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. 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 22 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.... LCD Backlight 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 LCD backlight 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 component called an inverter which converts dc within the unit to high-frequency ac which is required to drive the EL-panel. As this component deteriorates, 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.... 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. This was going to be a hard fix. My worst fears an' all that... I'll get back as soon as I get somewhere... or not 🙁... 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 2020NO MESSING AROUND WITH LOADS OF APPS NO CUT AND PASTE COMMANDS JUST SET THIS UP AS A DEVICE IN GOOGLE HOME OR AMAZON ALEXA Occasionally I build a batch of things which I put up here for sale. It's not worth me puting up an on-line shop just yet, so if you want anything, just contact me. Anyway, recently I built a bunch of smart momentary switches which will allow you to turn on your computer from your Google Assistant or Amazon Alexa. Just say "OK Google, switch on my computer" or "Alexa, switch on my computer" and it just happens! This item is basically a kit comprising some parts which need to be attached to the header on the motherboard inside your computer. Hence, this kit is ONLY suitable for computers which have an accessible motherboard and a standard motherboard header. UNFORTUNATELY THIS KIT 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 either find someone who is or think again about buying this. Included is a small ABS box which contains the electronics and which has an integral USB lead for power, a USB power supply, a standard PCI back-plate (this should fit most ATX sized cases) and a connection cable which connects the box to your computer via standard 3.5mm jack plugs. Oh and a link to download full instructions (in UK English only, I’m afraid), are also included. I can't exactly call this box an OK Google switch on my computer box! Instead, I'm just calling it 'SMS' which stands for Smart Momentary Switch. 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? £59 including postage to UK mainland. 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. 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. I designed the transformer myself as not only did I want the best linearity I could get over the entire audio spectrum but I also wanted minimum phase distortion, especially down the bottom end, something that cheaper transformers tend to generate. Anyway, I managed to get a bunch of these things made here in the UK and the TCI was born. 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 the signal path between your source and destination equipment is 'broken'. With the ability to easily lift the earth on the output (balanced side) of the TCI, these things are just great for getting rid of ground loop problems! IMPEDANCE All equipment has what’s called an input impedance and an output impedance. Impedance, like resistance and is measured in Ohms but differs in that it's frequency dependant. The impedance varies depending on the frequencies in the signal. Taking a guitar signal as an example, the input impedance of an amp let's say, will be different at 500Hz than it will 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 device. 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 exception; unbalanced outputs on a lot of ‘studio’ gear can be low impedance. This makes life a lot easier! The TCI has a low input impedance 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.... 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-for-Ever’ battery mod’. The battery is bang in the middle of the board 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, 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 If there's one annoying characteristic of an ageing Marshall JMP-1, then it's got to be the humming transformer. Anyone in the know, might think it strange that this box which resides in a 1U rack enclosure doesn't have a toroidal transformer. The thing is, the JMP-1 transformer chucks out several voltages including those required for the two valves and it's quite challenging to build all that into a toroidal design. So after a few years, the laminates inside the conventional transformer can become lose and start oscillating. The mechanical vibration can be annoying but does not appear on the audio signal. If you're heavily in love with your humming JMP-1 and want to do something about it, then give me shout! 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 bargin 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 the Marshyall JMP-1 forum on Facebook: https://www.facebook.com/MarshallJmp1/ If you have a JMP-1 and it'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. 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 Mains Switch11 February 2020Over the past couple of weeks, I’ve been designing 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 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 so as to properly drive the power amp. 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 which of course, the main (consumer) A/V 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! 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 seem 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. 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'r 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. You can pay here or 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) ...
