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PML-TX01 transformer for the Marshall JMP-1
And here it is... my PML-TX01 replacement and upgraded transformer for the Marshall JMP-1

This project has taken months but after tracking down Graham Sopp, the guy who designed the original transformer for the JMP-1, I'm delighted to announce that the PML-TX01 upgraded transformer for the Marshall JMP-1 is now available, featuring laminates made with a higher quality material.

You don't need to be a rocket scientist to notice that the original transformer in the JMP-1 is not stressed. Just take a peek at the regulators and you'll notice an obvious lack of heatsinks suggesting that the current draw from the supply lines is far from excessive. Measuring the input voltages to the regulators indicates that the voltage drop across them is not too much and of course we all know that the valves take very little current.

Marshall JMP-1 Regulators
The regulators in the JMP-1 don't have any additional heatsinking because they don't run hot.

So why then, does the JMP-1 transformer get so hot?

Well, it's due to the fact that the transformer's laminates oscillate. That's right. They oscillate so much that apart from the hum, a considerable amount of heat is also produced.

I spent a lot of time looking at the mystery of the Marshall JMP-1 humming transformer, refusing to acknowledge any issue with the laminates as I just didn't want to believe it. Once the penny dropped though, it all made sense.

My PML-TX01 replacement transformer for the Marshall JMP-1 is pin-for-pin compatible with the original.
My PML-TX01 replacement transformer for the Marshall JMP-1 is pin-for-pin compatible with the original.

It took a while but my first batch of PML-TX01 transformers is now here and while not perfect, it does perform better than the original Marshall TXMA-00014, with a little less hum and considerably less heat.

Although the laminates are made of a different material, thus lowering heat dissipation, the flux density of the device is the same, which means that the transformer could still hum.

Since heat generation is reduced however, we can now install a dampening material such as sponge or foam to the top of the transformer without fear of cooking the device. In tests, hum has been completely eliminated.


The transformer is soldered to the now very old, double-sided main board in the JMP-1. Please take care when removing the original transformer. It's a relatively heavy device and the through-hole plating isn't exactly the best quality. The last thing you want to do is strip it!


My PML-TX01 transformer is a high specification replacement for the TXMA-00014 transformer of the Marshall JMP-1 only. It is NOT suitable for other pre-amps such as the Marshall 9001.

If you have any questions about my PML-TX01, please don't hesitate to contact me or you can just

Nebula balanced outputs for the Roland MKS-70
This is Nebula, a new jack board for the Roland MKS-70 with an upgraded MIDI interface and balanced outputs.

Shortly after Christmas 2020, Guy Wilkinson and I were having one of our long and deep chats on the phone. I mentioned an idea to him which he seemed to like. Since then, I’ve been developing my idea and after working in my spare time for seven months, I’m delighted to announce Nebula – balanced outputs for the Roland MKS-70.

Nebula balanced outputs jack board for the Roland MKS-70 is very discrete
The back of these two MKS-70s look almost identical but one them hides a rather cool little secret.

Above, are my two MKS-70s. The bottom one is heavily modified with one of Guy’s OLED display modules, his P0004 power supply, Fred Vecoven’s PWM and his Super-JX flash upgrade. The other MKS-70 is unmodified but…. it does hide a secret. The top MKS-70 is running Nebula which means it has a revised, up-to-date MIDI circuit and… balanced outputs! SERIOUSLY????? Yes... SERIOUSLY!!!! 😀


There’s a big advantage to running balanced signals from your sources to your mixing desk or DAW audio interface and that is, an increased immunity to noise.

Environmental noise exists everywhere all the time. There’s human generated environmental noise such as radio signals, noise generated from switching circuits and so on but there’s also a considerable amount of natural background noise.

To screen signal carrying conductors from noise, cabling comprises a shield which is attached at one end, to the chassis of the source device and at the other, to the chassis of the destination device, thereby ‘extending’ the chassis of each device.

The problem is that screening isn’t 100% effective. We want our cables to be flexible and it’s impossible to achieve a 100% screen, while maintaining a good degree of flexibility.

Unbalanced signal plus noise
Unbalanced signal is in in green and noise is in red. Noise mixes nicely with signal!

NOTE for all the would-be rocket scientists out there. YES, I'm quite aware that the output waveform doesn't actually look like that but unfortunately packages like Adobe Illustrator aren't able to display a Fourier combination of what they see as a pair of vector traces. That's why I've blatantly written 'CRUDE REPRESENTATION'. In addition, I personally think this representation makes it easier to 'see' what's going on, particularly for the uninitiated.

So where were we? Ah, yes...

Another approach is that of the balanced line

Instead of sending a single signal, we send two signals; one being a copy but 180° out-of-phase with the first and then at the receiving end, we put things back to a single in-phase signal.

Noise is in-phase, everywhere. Nothing is producing a 180° out-of-phase load of noise, right? This means that noise is affecting both the in-phase and out-of-phase signals in exactly the same way.

With me so far? Good.

At our receiving end, the (differential) input stage rejects all signals that appear the same on both the in-phase and out-of-phase lines, this being… noise and ‘passes’ everything that is 180° out-of-phase… our signal.

Balanced signal plus noise
Similar to the previous figure but the out-of-phase signal is in blue. Now, take a closer look at the last pair of waveforms and you'll notice that noise (in red) is in-phase on both signal lines. When fed into a differential amplifier, any common phase signal such as this noise, is 'filtered' out or rejected .

So how cool is that?

I get asked this a lot but after reading the above, I hope you now understand that balancing the outputs of your equipment will NOT get rid of noise generated by your equipment. It’ll only reduce the effects of noise picked up by connections between your source and destination devices.

A figure known as the Common Mode Rejection Ratio (or CMRR) is the measurement in decibels, of how much signal that's common to both phases is filtered out by a device.

I don't like reinventing the wheel but since the jack-board not only has the MIDI sockets on it but also the MIDI interface hardware, I figured this might be an opportunity to review this thirty-five year old circuit.

MIDI circuit from MKS-70 Service Notes
Designing a new jack-board for the MKS-70 with balanced outputs was also an opportunity to potentially 'modernise' the MIDI circuit.

So anyway, there were a couple of initial design challenges. For example, the sockets on Nebula had to line up perfectly with the existing holes in the MKS-70 rear chassis.

Well luckily, a non-switching, 3-pole version of the original jack sockets still seems available. A bonus is that they’re the same size as the original 2-pole sockets. A version of the triple 5-pin DIN array is also still available. This was all really a big deal. If I couldn't get hold of those sockets, Nebula might not have happened because other 3-pole sockets are much wider than the original 2-pole (unbalanced) versions.

Then the obvious problem; there isn't exactly a lot of room to play with at the back of the MKS-70. How am I going to get a whole load of chips in such a small space? Even if I use SMDs, there's not a lot of room here. It seems like "the only way is up" and so I made the decision to build a double-decker (stacked PCBs) system.

Getting Nebula's PCB to fit, ended up being quite expensive. Everything had to line up properly and with four internal screw posts, six sockets and a switch, I must confess that it took me four attempts to get it all right. That's a lot of prototype PCBs! 🙁

Nebula balanced outputs for the Roland MKS-70
I usually get this kind of thing right first time but it took four attempts to get Nebula's bottom PCB to fit properly. No doubt the most expensive part of the project.

Back in the eighties, part of Roland’s design philosophy was to always support live music and believe it or not, even huge machines like the MKS-70, were designed with a mono-mix output, which could be fed straight into an amp, thereby allowing musicians to take their equipment down the pub for the odd gig. Madness, I know but you have to hand it to Roland for putting performing musicians first.

I’ve respected that philosophy and so the mono-mix output remains unbalanced.

Roland handled the switching of the outputs from stereo to individual, rather cleverly, by using switched, 2-pole jack sockets and a simple but effective array of resistors. Depending on which jacks were used, the MKS-70, either output a stereo pair or four individual outputs; Voice-board A left, voice-board A right and voice-board B left and voice-board B right.

Nebula balanced output sockets are the same series as the original sockets
With the exception of the 'total mix' output jack, Nebula's jack sockets are the non-switched 3-pole versions of the original switched mono jack sockets.

To do the same with 3-pole jacks was impossible as switched, 3-pole jack sockets are just too wide and would not have fitted or lined up with the holes in the rear chassis of the MKS-70. I therefore elected to use a manual mechanism to switch between stereo and individual outputs.

Nebula balanced output jack-board for ther Roland MKS-70 is available as DS or DIP switch version.
Nebula DS or DIP switch version. A DIP switch is used to engage a couple of relays that change the mode of the outputs from stereo to individual.

Accessible through the rectangular hole originally used for the output level selector switch, Nebula’s original design used a DIP switch to engage a pair of relays that changed the output configuration from individual to stereo. While this worked just fine, I then realised that if I used the original output level selector switch to do this job, the back of the MKS-70 would look unchanged. Pretty cool but that meant that Nebula would no longer be ‘plug-and-play’. Hang on a minute… why don’t I provide for both? So, the final version of Nebula has provision for either a DIP switch (Nebula DS) or use of the original output level selector switch (Nebula OS).

Nebula OS
Nebula OS or original switch version. Not quite Plug 'n' Play.

It's such a shame that the Alps SSP12240A, original output level selector switch isn't available anymore. If you decide to go for the OS version of Nebula, you'll need to remove the output level selector switch from the original jack-board and install it on to Nebula's jack-board. While the switch is quite robust, please do take care! This component cannot be replaced.

To keep things simple, I opted for a fixed output level of the mono-mix output and set it to 'high'. Hey come on. Does anyone even use that?

The first revision of Nebula used 0805 and even 0603 SMD passive components and SMD chips. It took a long time to build the prototype and it was apparent that if I was going to be making a few of these, doing things like this wouldn’t be practical or cost-effective. I therefore redesigned everything with 1210 package SMDs and full-sized DIP ICs. Amazingly, I still managed to get everything to fit on my two PCBs and so the version 2 was born.

I guess I should also mention that version 1 had dual stereo outputs when switched to 'STEREO'.

Nebula original rear sticker
Original Nebula reference sticker for the back of your MKS-70, showing dual stereo outputs.

A neat idea but I decided to ditch that one as I needed to be mindful of current consumption. Nebula's current draw from the +5V supply is a little less than the original jack-board as I'm using a SN74HC14 instead of the SN74LS04. More about that later. Apart from the headphone amp, Nebula ended up with an additional eight devices; four op-amps and four balanced line drivers, all pulling an additional +/- 40mA. In separate output mode, the relays kick in to switch routing, increasing current consumption from the +15V line by another 8mA. Even with upgrades like Fred Vecoven's PWM kit however, this won't be a problem but the dual stereo configuration might have been pushing things and I wasn't prepared to take the risk.

Choosing the op-amps and balanced line output drivers was only a minor challenge as I kind of knew what I was going to use. In fact, I like to think that I got a good balance (pardon the pun) between quality and cost. The fact that the ICs are DIP format means that I could now socket them and this got me to think that people could potentially try their own selection of chips. This was an unexpected bonus to using old-fashioned, full-size DIP ICs, LOL. 😀

The first Nebula had a gain-stage in-between the high impedance input buffers and the balanced line drivers. Like the dual stereo output idea, this also got scrapped but for different reasons; as the balanced outputs yield 6dB over the unbalanced versions, more gain wasn’t necessary. The other reason was that apart from the headphone amp and hence, the mono-mix output, the outputs on the original jack-board are basically driven from the last op-amp (you guessed it, a M5218) on the respective voice-board. This means that the jack-board itself, doesn’t generate and hence, pass on any noise on to the outputs. As such, any replacement jack-board would have to compete with something that’s dead quiet.

Nebula version 2 3D capture from EasyPC
This is a 3D capture of the final versions of Nebula's PCBs, from EasyPC, my design software.

Version 2 therefore, had a simple array of unity gain, non-inverting voltage-followers offering a high impedance to the outputs of the voice-boards and lots of drive for the inputs of the balanced line drivers.

I’ve always used dedicated balanced line drivers such as the SSM-2142 and the THAT-1646, in preference to messing around with various configurations of op-amps. The results are ALWAYS better. This time around, I settled on the Texas Instruments DRV-134. Specification-wise, all these chips are pretty much the same. With the SSM device being long obsolete however, the choice was narrowed down to two.

For superior performance, Nebula uses dedicated balanced line driver ICs as opposed to an op-amp configuration
For superior performance, Nebula uses dedicated balanced line driver ICs as opposed to an op-amp configuration.

Designing and manufacturing components for vintage equipment doesn’t make for a good business plan. In fact, I dare not tell my bank manager that I do this kind of work. By definition, your market is technically shrinking as some machines sadly die and are beyond repair. The quantities of respective systems that I’m able to make isn’t exactly earth-shattering which means components are purchased in relatively small batches and so I'm unable to take advantage of quantity discounts.

The point I’m making is that I do everything I can to keep the price of my designs as low as possible but without sacrificing performance or quality. With negligible technical differences between the THAT-1646 and the TI DRV-134, I'm not ashamed to admit that the decision to use the latter, was based solely on cost. Having said that, if for whatever reason, you want to swap out the DRV-134s for the THAT-1646s, or even SSM-2142s if you still have some, you’re more than welcome to do so. The devices are all pin-for-pin compatible.

Balanced line driver ICs are NOT op-amps! Indeed it should be noted that one of the crucial differences is their input impedance which in the case of the DRV-134, is a mere 50kΩ, much, much lower than an op-amp. The other devices I mentioned have even lower input impedances. Dealing with low input impedance devices, was another reason I was reluctant to design a passive array (similar to what Roland did) and hence, implemented the previously mentioned unity gain, non-inverting voltage-followers, to go in between the outputs of the voice-boards and DRV-134s.

Nebula produces high quality balanced outputs
I've designed a lot of balanced output stages over the years and in my experience, using dedicated devices like the DRV134 always delivers accurate, high quality results.

Like all the stuff I design, Nebula includes a few extras and so the design incorporates the following refinements:

  • diodes on all output phases to protect against high capacitance loads and phantom power (we’ve all done it),
  • ferrite bead / capacitor filter network on each phase of each output to reduce the effects of RFI / EMI.
  • Capacitors on ‘SENS’ outputs of balanced line drivers to mitigate effects of dc offsets on outputs.
Nebula has diode protection on all output phases
Nebula has RFI / EMI filtering and diode protection (pictured) on all output phases.

Some will argue the point of implementing the above in favour of cost but to be honest, I just wouldn’t have been happy had I missed all of that out.

Nebula retains a driver IC for the front-panel headphone output but it’s been upgraded from the original M5218L, to one of my favourite ICs for headphone amp applications, the NJM-4556AD.  Like the NJM-2068D that I used for the buffers, the 4556 is a well spec’d dual op-amp but, it’s also particularly good at driving high-reactance loads… like headphones.

Nebula uses the NJM4556 for the headphone amp as it's great for driving high reactance loads... like headphones
Nebula uses the NJM4556 for the headphone amp as it's great for driving high reactance loads... like headphones.

Having worked for Simmons and Roland back in the eighties and having designed a lot of audio equipment over the decades, I didn’t doubt that Nebula’s audio and MIDI wouldn’t work. I was however concerned about how the MKS-70’s CPU would respond to the revised MIDI circuit.

Nebula MIDI sockets
Nebula has upgraded MIDI as well as balanced outputs.

At the time, Roland opted to use the TLP-552 CMOS opto-isolator, which is much faster than devices like the Sharp PC-900 which although very popular in the eighties, had a Darlington output. I looked carefully at a variety of modern equivalents and came back to my favourite MIDI opto-isolator; the 6N137.

Nebula uses 6N137 for MIDI opto-isolator
The opto-isolator on Nebula is the 6N137, one of my favourite devices for this kind of stuff.

I don’t really know why its successor, the 6N138 is so popular for MIDI, as the 6N137 is a far superior device, especially if you’re looking to do something like Nebula. Quite simply, the 6N137 is faster, more accurate and has better output drive meaning that for driving an ol’ girl like the MKS-70, it’s absolutely ideal.

Similarly, I substituted the SN74LS04 hex inverter, with a 74HC14. Apart from being a low-power device (HC), the 74HC14 has Schmitt trigger inputs, meaning that the output of each stage, only switches between states (0V and 5V or '0' and '1'), when the input crosses a specific threshold. Theoretically, this makes the MIDI circuit less likely to pass spurious voltages on to the processor.

Well, I’m pleased to confirm that after extensive testing, Nebula’s MIDI circuit works just perfectly, supplying a much ‘cleaner’ MIDI signal to the CPU. In fact, your MKS-70 will love it! 😊

Oh, by the way, since MIDI OUT also passes through two inverters of the 74HC14, the advantage works both ways, meaning that the MIDI data stream leaving your MKS-70 will be, well... squarer!

As per the original circuit, All MIDI lines are fitted with ferrite beads, again to reduce the effects of RFI / EMI.

Nebula comprises two PCBs; the top (audio) PCB has the main audio components on it and the bottom (jack) PCB has the headphone amp, audio jacks, MIDI sockets, selector switch and MIDI circuitry.

Nebula balanced outputs for the Roland MKS-70
Nebula has two tiers; one for audio and one for MIDI, sockets and headphone amp.

A couple of otherwise redundant inverter stages on the 74HC14, are used to drive a conveniently placed LED, thereby providing a MIDI status indicator. This means that with the lid off your MKS-70, you can easily check to see if MIDI data is coming into the unit. Please note that ALL MIDI data will trigger the LED, including clock and active sensing as there's no filtering here, it's just raw MIDI data.

If you find it distracting, a jumper close to the MIDI indicator LED, allows you to turn off this function.

Nebula's MIDI status LED can be turned on and off via a simple 3-way header
Nebula's MIDI status LED can be turned on and off via a simple 3-way header / jumper.

The DIP switch (DS) version of Nebula is plug-and-play and if you really want to keep the back of your MKS-70 looking factory, then transplanting the output level selector switch makes Nebula virtually plug-and-play. The positions of the headers connecting the original jack-board to the rest of the MKS-70, have been respected and it’s only the audio connection from the MKS-70 voice-boards that is slightly different, being on the top (audio) board. This means that there's no need to mess with Roland's impeccable wiring loom! 🙂

Nebula balanced outputs for the Roland MKS-70, installs quickly and easily
Nebula installs quickly and easily with headers all in the right place for the internal cables.

To ensure the best visibility and accessibility, I thoroughly recommend that the MKS-70 voice-boards be removed prior to fitting Nebula. I should also point out that there's only a couple of millimetres clearance between the voice-boards and Nebula's double-decker PCBs, so trying to fit Nebula with the voice-boards in place... well, Nah!

Nebula is supplied assembled and the top and bottom boards need to be separated prior to installation. With a gentle pull, Nebula’s boards easily come apart, allowing the jack-board to be lined up and secured as per the original.

I personally found that after removing the metal jack socket retention plate from the original jack-board and fitting it to Nebula’s jack-board, lining up the sockets with the holes in the MKS-70 rear panel and then loosely screwing the jack-board to the four internal posts using the supplied 30mm PSB spacers, followed by gently securing the external screws, was the most reliable method of installing Nebula.

Original MKS-70 jack-board showing jack socket retention plate
Original MKS-70 jack-board showing jack socket retention plate.

One last point on assembly; unless you have plans to send your MKS-70 on a deep space mission out of the solar system, please, please, please DON'T OVER-TIGHTEN the screws!

The multi-pin connections between Nebula’s boards are soldered with the boards in place and should therefore line up nicely, after the 30mm PCB spacers are fitted to the jack-board. Once secured, just make a final check to see that all twelve pins of CN7 and all three pins of CN8 are properly mated with CN5 and CN6, respectfully, prior to securing the audio-board with the four screws.

Nebula balanced outputs for the Roland MKS-70 inter-board connectors are solder with boards assembled for perfect alignment
Nebula's inter-board connectors are soldered with boards in place to ensure perfect alignment.

So, once I finally got things to fit properly, I was actually really excited about Nebula balanced outputs jack-board for the MKS-70 and to be honest, I found it a bit difficult to keep quiet. In fact, I couldn’t help myself and let slip to some of my regular customers. Oh boy… I couldn’t believe the response and although Nebula hadn’t even been built, let alone properly tested, suddenly I had a small backlog of orders. Thanks for the vote of confidence, guys but seriously?!!?!

Although I have recently found new premises for Plasma, following last year’s flood, I’m still working at home with limited access to my ‘usual’ equipment and so the development of Nebula balanced outputs for the Roland MKS-70 had other, indirect challenges. It was however, a fun little project and I’m so pleased that it all worked. Yes, I wasted a little time and money on getting things to line up and fit properly but I knew what I was letting myself in for. Once the version 2 prototype with DIP package ICs was built however, it was truly rewarding to see it all come to life.

Nebula balanced outputs jack board for the Roland MKS-70
A nice snug fit, Nebula kind of looks like it belongs, like it's always been there.

I have now installed Nebula in both of my MKS-70s and at the time of writing, Nebula is also working perfectly in two customer units (thanks Jason and Chris). One more installation and that’s my first batch gone! 😊

Unlike some vintage synth upgrades, Nebula isn’t exactly a “Must Have”. On the other hand, I’ve always thought it odd that hot, unbalanced signals need to be attenuated via a DI box and then re-amplified, so as to get balanced signals. It just seems such a waste. Nebula fixes that and also gives the MKS-70 a most welcome MIDI boost.

Although incredibly simple to install, I still feel obliged to write installation instructions which will take a while. In the meantime however, if you’ve got any questions about Nebula balanced outputs for the Roland MKS-70, please don’t hesitate to get in contact. If you're convinced, you can just buy it.

UPDATE - 19th August 2021

I'm always reluctant to just post my stuff (like Nebula) on social media groups as I  respect the rules which often include restricting self promotion and sales, for example. I will therefore endeavour to contact one of the administrators to ask their permission to do so. On this occasion, however, I feel rather humbled that Keith Meiere, admin' of the Roland JX-10 and MKS-70 Synthesizers Facebook group, put up a post featuring Nebula, before I'd even approached him. Thank you so much, Keith.

People have commented on the idea of a version of Nebula for the JX-10. Yeah, I forgot to mention that. Of course designing something like Nebula, you kind of think that you're doing so for two machines; the MKS-70 and... the JX-10. The problem is that the JX-10's jack-board is really quite different to that in the MKS-70. Being a performance keyboard, it has a load more sockets than it's rack-mount cousin. On top of that I don't have a JX-10! 🙁 but... let me think about it...

Plasma Music Limited -

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:

  1. I can be confident that workers are treated fairly and earn a proper wage.
  2. I can be confident of the standard of quality of each item that is delivered to me.
  3. Communication is important and using local manufacturers, all correspondence is quick and understandable.
  4. I believe in supporting the local economy.
  5. I can be confident that the disposal of manufacturing waste is managed properly and in accordance with national and EU law.

Plasma Music uses local manufacturers

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.

Yesterday, 4th August, was my birthday. My youngest daughter Tsunami has moved back home after finishing university and my eldest daughter Katana, kindly came down from Manchester for a few days.

Got up in the morning and on the coffee table amongst the cards, was what appeared to be a picture all wrapped up.

I opened it and got the chock of my life! My wife Julie had commissioned my good friend and excellent artist to paint this:

Portrait of Alexander Bhinder 2021 by Tony Burlinson

It's a million times more amazing in the flesh and I'd just like to thank Tony and Julie for getting together and delivering this magnificent piece of art.

As if that wasn't enough, half way through the morning, the girls disappeared only to call me to the house that will be the location of the new studio.

Seriously?!?!?!? A frigin' Marshall fridge!!!!

Marshall fridge for my birthday

The kitchen has been ripped out and the kitchen / diner has been prepared for something a little more efficient, let's say. Now I can't wait to get things finished so I can install my new appliance. 🙂

Thank you Julie, Katana and Tsunami for making this the best birthday ever! 🙂

Flooded - Plasma Music Lab (2020.08.12)
It only took ten minutes to cause so much damage.

12th August 2020 and if the COVID-19 pandemic wasn’t bad enough, my studio flooded. A torrential downpour overwhelmed the badly maintained drainage system in the road leading to my studio and within ten minutes, the basement was under 25cm of dirty road-water. You can read all about that here. A devastating experience, I was in no state of mind to begin looking for new premises for Plasma Music.

Despite having been at my previous premises for ten years, I was concerned that the same thing might happen again and reluctantly, made the decision to leave.

20th November 2020 was my last day. On the evening of the 19th, my wife Julie and my good friend Tony, made one last trip to the old studio. It was a little emotional, to say the least. All three of took a sigh and were very aware of what we were individually feeling. I designed the whole place and Tony paid for a lot of the build. ‘Area 51’ had a lot of good memories, not just for us but many friends and customers. A final goodbye, Tony and Julie reminded me that it was time to move on.

Since then, my wife and I have been carefully negotiating the huge stacks of equipment that accommodate every corner of our home. Of course I haven’t been able to do anything music-wise but I have tried to carry on with repairs, service and design and manufacturing. It’s been a real strain. Trying to dig out tools, equipment and parts has sometimes been like looking for a needle in a haystack.

New premises for Plasma 2021
Last week I ripped out the old kitchen. With a lot of help from my friend Mike, a scaled down, galley-style kitchen will be going in.

Anyway, seven months later and I might have new premises for Plasma Music. It’s a large detached house which is going to need a lot of work before I even consider moving my stuff in. Last week I ripped out the kitchen which is going to be replaced with something a little scaled down. Upstairs isn’t too bad and basically just needs redecorating. Apart from the kitchen, downstairs also needs a lot of the flooring replaced and a little damp sorting out.

I hate DIY!
You can probably tell that I'm not a natural!

I’d just like to take this opportunity to say THANK YOU to my family, friends and neighbours. My youngest daughter, Tsunami was actually responsible to motivate me (kick my arse) to make a start. She’s just graduated with a 1st but has put her dad first, too!

My wife Julie, has been incredibly patient over the past few months, what with our home seemingly disappearing under a deluge of amplifiers, keyboards, mixing desks, guitars and a lot more. Julie has also been helping with stripping wallpaper and organising skips, etc.

Then there’s my neighbour Mike Graves who pulled up the damaged flooring and has already made a start on preparing for the new galley-style kitchen. Mike knows a lot more than I do about building and has been so helpful sorting out lots of bits ‘n’ pieces.

Plasma Music moves into new premises.
I don't really have the patience for this kind of stuff.

While focusing on the inside of the house, another neighbour, Joe Scibetta, has done an awesome job on the gardens. Joe worked tirelessly to get the lawns into a half decent state. He ripped down the old shed and removed a tree that was growing out of control. He even put up a new fence panel which apart from looking awesome, has improved security from the front aspect of the property.

I reckon it’s going to take a couple of months before I consider moving stuff over but I quite honestly, can’ wait. Of course I’ll keep you posted.

I'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.

TCI Type 1 2-channel unbalanced to balanced converter
After having made possibly hundreds of these over the years, my Transformer Coupled Interface Type 1 is now available to everyone.

TCI started as a problem solver in my own studio. Before long, friends asked me to build TCIs for them and then they got the attention of musicians, engineers, producers and even audiophiles, further afield. With a proven track record, there are already hundreds of these boxes all around the world, some of which may be over twenty years old! Out of all the things I've built over the years, people seem to love my humble TCI.

Making a commercial product is a great opportunity to offer a truly high-specification device, to a wider audience and I'm very proud to have squeezed all of this in:

30Hz – 30kHz
6.4kΩ - 6.5kΩ
2 x ¼” (6.35mm) 2-pole jack socket
2 x 3-pin male XLR socket (pin 2 is in-phase)
(L) 80mm x (W) 80mm x (H) 47mm inc. feet

The title says it all and you've just read the specifications but there's even more information about my Transformer Coupled Interface Type 1 unbalanced to balanced converter in my post, here.

Yes, I know; what about the 'Type 2'. Well, the Type 2 is (you guessed it) a passive 2-channel balanced to unbalanced converter. Indeed I've also built a few of these. I'm going to see how the Type 1 does before I consider releasing the Type 2.

There's also a Type 3. That however, is for another time... and another post! 🙂

This 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.

RE-MPG-80 replacement rack ears for the Roland MPG-80
RE-MPG-80 replacement rack ears for the Roland MPG-80, mounted to my new machine!

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…

RE-MPG-80 replacement rack ears for the Roland MPG-80
I'm really happy with these replacement rack ears. They look stunning.

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.

RE-MPG-80 replacement rack ears for the Roland MPG-80
A perfect fit and the finish is just great!

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.

RE-MPG-80 replacement rack ears kit
Of course, you get the rack ears but also included are four fixing screws that seem much 'blacker' than the originals.

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.

Plasma Music Limited -

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:

  1. I can be confident that workers are treated fairly and earn a proper wage.
  2. I can be confident of the standard of quality of each item that is delivered to me.
  3. Communication is important and using local manufacturers, all correspondence is quick and understandable.
  4. I believe in supporting the local economy.
  5. I can be confident that the disposal of manufacturing waste is managed properly and in accordance with national and EU law.

Plasma Music uses local manufacturers

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.

Broken Data Cartridge Slot on Roland MKS-80
You might just be able to make out that the M-64C data cartridge is kind of just hanging in there. It isn't sitting squarely in the data cartridge slot.

Over 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.

MKS-80 Data Cartridge Slot Rear Assembly
MKS-80 data cartridge slot rear assembly.

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.

MKS-80 Data Cartridge Slot Front Assembly
MKS-80 data cartridge slot front assembly showing intact top screw flange.
MKS-80 Front Data Cartridge Slot Assembly Attached to Front Metal Chassis
MKS-80 data cartridge slot front assembly is attached to the front metal chassis (under the front panel), via two M3 screws.

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.

V06 Bracket for Roland MKS-80 Data Cartridge Slot
A simple but elegant solution, the V06 Bracket sits on top of the Aurora Board B (or Board Bx) and is a great fix for a broken data cartridge slot on a Roland MKS-80.

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?

V06 Bracket for Roland MKS-80 Data Cartridge Slot
V06 showing convenient cut-out for access and measurement of CR123 Live Forever battery on Aurora Board Bx.

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.

V06 Bracket for Roland MKS-80 Data Cartridge Slot
6mm high-density neoprene rubber, provides excellent shock absorbency between the data cartridge slot's rear PCB and the V06 bracket.

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! 😀


  • 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.
The V06 is supplied with four 20mm M3 stand-offs and two 6mm neoprene rubber pads with double-sided adhesive tape.
The V06 is supplied with four 20mm M3 stand-offs and two 6mm neoprene rubber pads with double-sided adhesive tape..

If you have already bought Aurora and would like a V06, please just get in touch.

UPDATE - 4th May 2021

Jed Allen, first V06 customer
Jed Allen collecting his Aurora powered Roland MKS-80 with new V06 bracket.

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. 🙂

Give your Roland SH-101 a little TLC

Recently, 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.

Roland SH-101 serviced at Plasma Music
The dust covers underneath the Portamento and transpose switch levers, just crumbled. Difficult to see in this picture but I managed to replace them with some of my black magic thingy!!!

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.

Roland SH-101 keyboard bed after decades of neglect
Roland SH-101 keyboard bed after decades of neglect and being kept in a smoker's environment.
Keyboard contact strip after decades of neglect
Same with the keyboard contact strip. Looks absolutely awful.
Roland SH-101 keyboard bed and contact strips after cleaning
Before and... after. I got lucky with this one. After such a long time (and especially after long-term exposure to tobacco smoke), it's quite common for the contact strips to tear when removing them from the keyboard bed.

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.

A sadly familiar sight to many Roland SH-101 owners - a broken screw post
A sadly familiar sight to many Roland SH-101 owners - a broken screw post.

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.

Replacement M3 pillar on Roland SH-101 keyboard chassis
Here's one of the two replacement M3 support pillars that I fitted on to the keyboard chassis. Two non-self-tapping screws, pass through the metal bottom-case and into these pillars.

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.

Roland SH-101 serviced at Plasma Music
Dan's Roland SH-101 almost looking like new again and definitely feeling and sounding a lot better than when it came in.

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!

Nice shiny looking and smooth feeling keys
WOW! Nice shiny looking and smooth feeling keys.

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 Pro Solo Mk 3
One of several gadgets made by Kenton Electronics that'll get your Roland SH-101 connected to your MIDI studio, the Pro Solo Mk 3 stand-alone MIDI / CV converter, is fast and accurate.

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.

RE-MPG-80 replacement rack ears for the Roland MPG-80
RE-MPG-80 replacement rack ears for the Roland MPG-80, mounted to my new machine!

Hiwatt amp found in pyramid
A truly remarkable find - Rokatiti tomb, chamber 3C showing Hiwatt DR-103 amp, tucked in round the back.

A 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.

Hiwatt amp found in ancient tomb
And this is chamber 21F. Check out the Hiwatt DR-103 at the back.

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.

Hiwatt DR-103 found in ancient tomb is full of sand and rubble
Ancient Egyptian sand and rubble inside this Hiwatt DR-103.

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.

Hiwatt amp found in ancient tomb needs cleaning before anything else
These amps needed serious cleaning before I can do anything else.

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.

Hiwatt DR-103 switches need replacing. One has been replaced before.
Quite unsafe, these switches on the second DR-103 really didn't look too healthy. In fact, at some point, one of them had already been changed.

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.

New switches on Hiwatt DR-103
Satisfying the two objectives of keeping things as original as possible and making these amps sing again, was a challenge but for the sake of safety, I decided to fit new switches on the second amp.

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.

Hiwatt Attention to Detail
Check out that wiring! No wonder these Hiwatts were often referred to as "posh Marshalls".

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...

Rock Faro Rokatiti
Undoubtedly the loudest 100W amps ever, Pharaoh Rokatiti could be heard jamming with his Hiwatt, for miles.

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.

Hiwatt DR-103 renovation - new screws and screw-cups
New screws and screw-cups where appropriate, made a big difference.
Hiwatt DR-103 renovation - new feet
Having disintegrated to a few millimetres in height, the original feet were at the point of crumbing into dust and so I fitted new ones.

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.

Hiwatt DR-103 with Marshall branded EL34s
I decided to use Shugaung manufactured EL34Bs in these Hiwatt DR-103s. Derek passes on the great deal he gets from Marshalls, on to his customers. Hey, check out that heatshield at the back and err... no sand!

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.

Hiwatt DR-103 - original and new replacement capaciotrs
The difference in terminal orientation and pitch between the original capacitor on the left and the new capacitor on the right, isn't normally an issue. On this occasion however, I was keen to retain the famous, tidy Hiwatt wiring which made the power capacitor transplant really quite challenging.

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.

Second amp after clean up
Here's the second amp with new power capacitors. Notice the holes in the rear of the chassis which were part of the mods and which I didn't hesitate to remove. I later cleaned these up and then plugged  them.

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 .

Plugged mod hole in front panel of Hiwatt amp found in pyramid
It was unfortunate that the second amp had holes drilled in the chassis. I did my best to cover these up as tastefully as possible.

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. 🙁

Hiwatt DR-103 with plugged mod holes
You can get away with a couple of holes on the rear panel but straight through the serial number plate? SERIOUSLY?!?!?!

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...

Pre-amp valves in Hiwatt DR103
Harma ECC83 pre-amp valves from my friend, Derek Rocco at Watford Valves.

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.

Testing Hiwatt amps found in pyramid
It was always felt that the only way to get an overdriven sound out of a Hiwatt, was with an overdrive or distortion pedal. Indeed the headroom on the inputs and the power amp is considerable.

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 DR0193 renovation 1

"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!

Alex with two Hiwatt DR-103s that have been refurbished after having been discovered in pyramid
Hiwatt amps found in pyramid looking like new and sounding BIG! Hey, Alex, is that one of Pharaoh Rokatiti's Shark-Fins???.

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.

Electric Warrior by T Rex
Simple but iconic, the album artwork on Electric Warrior by T. Rex. When I saw this awe-inspiring image, I just knew what I wanted to do for the rest of my life.

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-70 and JX-10.

Introducing 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!

MCK-70 in action

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. 🙂

MCK-70 Boot
MCK-70 will work on the Roland JX-10 as well as the MKS-70.

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?


  • 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!