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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. Unfortunately, noise mixes well with audio signals!

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 signals such as this noise, are '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 noise that's picked up 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.
Here's a very early Nebula version which used a DIP switch to engage a couple of relays that change the mode of the outputs from stereo to individual. While functional, I didn't really like this approach.

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 stereo to individual. 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 original versions of Nebula had provisions for either a DIP switch (Nebula DS) or the reuse of the original output level selector switch (Nebula OS).

Nebula OS
Nebula original Alps SSP12240A version worked just fine and looked great but required the output level selector switch to be removed from the old Roland jack-board and repurposed. Nebula would no longer be Plug 'n' Play as I originally intended it to be.

Well, I wasn't happy. That switch thing bugged and bugged me. As mentioned, one of the objectives of Nebula was that it should be plug and play with no soldering involved. A medium sized Phillips screwdriver should be the only requirement to fit my new balanced outputs jack-board for the Roland MKS-70.

The problem was that I couldn’t find a right-angle slide switch big enough. Yes, you read correctly; BIG enough.

Modern switches are much smaller than what was used in the eighties and I couldn’t find anything with adequate clearance between the lever and the bottom edge of the slot cut-out on the rear of the MKS-70.

But I persevered,  my quest continued and indeed I eventually found a switch which was physically as similar to the original as it was going to get.

Nebula with final choice of switch
And finally... I found a very suitable switch to change Nebula's output mode from stereo to individual.

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, version 2 was born.

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

A neat idea but I decided to ditch that one as I needed to be mindful of current consumption.

Nebula Output Configuration Label
Nebula is supplied with a self adhesive label detailed how to switch between stereo and individual output modes.

Some users get confused about the four outputs on the back of the MKS-70. Well, the MKS-70 has two module-boards and each module-board has two (stereo) outputs. Both pairs of outputs can be mixed so as to provide a simple stereo output from the instrument.

The outputs from each module-board however, can be accessed individually. Some users take advantage of this feature as it's like having two synthesisers and opens up a whole new bunch of possibilities.

Nebula Output Configuration
Here's a quick reminder of how to connect the outputs from the MKS-70 so as to take advantage of either stereo or individual outputs..

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 a bit ambitious and with no practical benefit in the real world.

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.

This is a 3D capture of the final versions of Nebula's PCBs, from EasyPC, my design software
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
Delivering superior phase coherency, Nebula uses individual, dedicated balanced line driver ICs to produce balanced outputs of each channel, as opposed to a dual op-amp configuration.

Keeping costs down without sacrificing performance or quality is a challenge common to any design process. 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 10kΩ, much, much lower than an op-amp. The other devices I mentioned have similar 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 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.

These refinements have nothing to do with balancing the signal. They're included so as to ensure that the output of your MKS-70, is as clean and as noise-free as possible and that they're protected against bad things from the outside world!

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. At the end of the day, Nebula does make the MKS-70 sound better!

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 changes.

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

Roland used the TLP-552 CMOS opto-isolator in the MKS-70's MIDI circuit, which was much faster than devices like the standard and very popular Sharp PC-900 which also 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 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 logic '0' and logic '1'), when the inputs cross 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, which is used as a MIDI status indicator. With the lid off your MKS-70, you can easily check to see if MIDI data is coming into the unit. Please note however, 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 next to the LED, allows you to turn it off.

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 two of my three 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! 😊

To conclude, here’s what Nebula offers:

    • Plug 'n' Play installation only requiring a Phillips screwdriver and a little patience
    • 6dB hotter signals than unbalanced outputs
    • Increased immunity to external noise
    • Better signal-to-noise ratio
    • Greater dynamic range
    • Reduced crosstalk between left and right channels
    • Reduced crosstalk between module-boards
    • More powerful and cleaner headphone sound
    • Increased MIDI stability

Nebula is available for purchase here:

Nebula balanced outputs jack-board for the Roland MKS-70

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...

UPDATE - 17th October 2021

Firstly, I'm pleased to announce that detailed and illustrated installation instructions for Nebula are now available for download after purchase.
Thomas Dolby's Roland MKS-70

Secondly, many thanks to Chad Kainz for his lovely write-up, detailing his Nebula installation. You can read all about his ex-Thomas Dolby MKS-70, how he did it and check out his brilliant photos, here.

Thanks Chad. 'Makes me feel very humble.

UPDATE - 5th October 2022

I love it when people send me interesting questions and today I received an e-mail asking if Nebula would help reduce crosstalk between the MKS-70's outputs. The answer is YES but you can read all about why and how here. 😀

UPDATE - 15th November 2023

I'm very lucky to have such awesome customers and occasionally, I get some feedback which makes my day. 'Rob H' recently contacted me and here's an extract from his message:

"Love the new output board for the MKS-70, btw. I installed it a few weeks back, and it really improved the overall quality of the sound."

UPDATE - 19th January 2024

Screened audio cables are part of this Roland MKS-70 full upgrade
My new screened audio cables for the Roland MKS-70, improve the signal quality going into Nebula.

Giving the Roland MKS-70 balanced outputs improves noise rejection between the MKS-70 and the destination device, improving overall sound quality. Nebula can't do anything about noise picked up between the outputs of the module-boards and its inputs.

To improve the quality of the signals going into Nebula, I therefore designed a pair of screened audio cables which do indeed reduce the noise picked up from within the MKS-70. You can read all about them here.

My screened audio cables for the Roland MKS-70 are now offered as an option when you purchase Nebula.

UPDATE - 22nd March 2024

Nebula is one of the least cost-effective things I make. High quality components and very labour intensive, I simply can't charge for the actual time it costs to make. Luckily, I love what I do and when I receive e-mails like this, it makes it all worthwhile.

"Thank you - label received! Also, I installed Nebula last week with no issues and it works fantastic! Very happy that my MKS70 is louder and clearer now - so much more useable, like a new synth!

Many thanks;

Matthew " 🙂

UPDATE - 21st April 2024

Nebula-X Rev. 1.0 Design Preview

Almost as soon as I announced Nebula, people were asking if I was going to develop a balanced outputs jack-board for the Roland JX-10. I seriously considered the idea but there were just too many complications, unique to the JX-10.

For a start, the JX-10 is a performance instrument so it has a mired of sockets on the back panel, all of which are mounted on the jack-board and many of which are excluded from the studio version of the machine, the MKS-70. Apart from overcoming various technical problems, keeping cost down would be a big challenge.

Secondly, the programmer port is also mounted on the jack-board. Indeed, with the exception of the data cartridge, anything you can connect to a JX-10, is done so via the jack-board.

While the assigner-board and module-boards in the JX-10 and the MKS-70 are identical, the jack-boards are very different indeed with the former being considerably more involved.

Anyway, regular visitors to my website and my Facebook page will be aware that several weeks ago, I developed a pair of screened audio cables for the Roland MKS-70 which greatly reduce noise picked up from within the instrument, as a result of all of that noisy eighties electronics.

My new cables were supposed to available in two versions; one for the MKS-70 and one for the JX-10 and were supposed to be called “screened audio cables for the Roland Super-JX”. Well, you learn something new everyday and while developing the cables, I was most surprised to discover that unlike the standard 'wires' that connect the module-boards to the jack-board in the MKS-70, the same connections are made using screened cables in the JX-10.

So why is the JX-10 still so noisy?” I asked myself.

Well, there are several reasons but to cut a long story short, the idea of ‘Nebula-X’ was actually born from a quest to reduce JX-10 noise at the audio outputs and not to provide the instrument with balanced outputs. As it happened, I thought I’d kill two birds with one stone, as they say. Well, seeing as people asked, what else could I do?

Nebula-X Rev. 1.0 Design Preview

Incorporated into the Nebula-X design, there are a couple of cool tricks which I've used before over the years, with a view to combat internal noise. I'm afraid it's all way too much to go into any depth here but of course when Nebula-X is released, you'll be able read all about it!

What I will tell you, is that just like Nebula for the MKS-70, Nebula-X uses the same balanced line driver ICs and also has upgraded MIDI circuitry which includes an on-board MIDI activity indicator.

I'm afraid things are still a few weeks away until Nebula-X hits my on-line store. I still have to order PCBs and there's a lot of testing to do but... 

Stayed tuned, Super-JX fans! 🙂

Nebula-X Rev. 1.0 Design Preview showing MIDI activity indicator
Nebula-X has a lot of the cool things that I used in my Nebula for the MKS-70 design like a convenient MIDI activity indicator.

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.

Following 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 MKS-70 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 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 Wilkinson's switched-mode power supply installed intoa Roland MKS-70
A P0004 switched-mode replacement power supply installed in a Roland MKS-70. Look... no transformer!

There are two MASSIVE hidden bonuses when using something like Guy's P0004 power supply;

  • Unlike the original Roland PSU, the +5V supply on the P0004, is NOT derived from the +15V line and is fully independent. Hence, any fault on the +15V line, won’t affect the +5V supply.
  • In the event of a failure, the respective supply will simply stop working and chuck out 0V.

Big deal, so... Well, sadly, I occasionally see a MKS-70 which has had a failure of the +5V supply. If the failure is as a result of the +15V going wacky, this often results in the +15V line jumping to like +22V, thus maxing out the +5V regulator circuitry and taking out your assigner board. That’s basically a bricked 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.

Roland Super-JX upgrades - Guy Wilkinson's Super-JX OLED upgrade module
Guy Wilkinson's Super-JX OLED module.

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! 😛

Guy Wilkinson's OLED installed in MKS-70
Guy Wilkinson's OLED for the Roland Super-JX, installed in a MKS-70.


Guy Wilkinson's VFD module looks more like the original Roland display. With Fred's firmware, brightness of the GU-280 can be changed.

Guy Wilkinson's GU-280 VFD for the Roland MKS-70
And here's Guy's GU-280 VFD for the Roland Super-JX, also installed in a MKS-70.

As I continued my research into the world of Roland Super-JX upgrades, I came across 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.

Roland Super-JX upgrades - Vecoven PWM kit.
Assembled PCBs of the Vecoven PWM upgrade for Roland MKS-70 and JX-10.

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?

Roland Super-JX upgrades - the Vecoven Super-JX Flash Module
Vecoven Super-JX flash module (highlighted in red) installed in a Roland MKS-70.
Vecoven Flash Module Installed In Roland MKS-70
Voice boards lifted for a close-up view.

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.
    • 1 x insulating boot for IEC socket.
    • 2 x Pre-cut earth leads terminated at one with earth tag.*
    • 1 x M3 earth tag (for one side of IEC socket).

*One earth lead connects IEC earth to chassis via one of the screws that secures the IEC socket. The other earth lead connects the P0004 power supply to the chassis via any M3 screw.

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.
It is paramount that if fitted, a 2-pin IEC C10 mains socket be replaced with a 3-pin IEC C14 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.

Custom mounting bracket for Vecoven PWM mod for MKS-70
Custom mounting bracket for Vecoven PWM kit in Roland MKS-70. The benefits of using this include no holes to be drilled in the voice-boards, makes general maintenance so much easier and of course your MKS-70 can be put back to factory any time.
Custom mounting bracket for Vecoven PWM mod for MKS-70 installed
An elegant solution (even if I say so myself), my custom bracket makes installing the Vecoven PWM mod into the Roland MKS-70, so much easier.

The IDC connectors I've used, don't have the tidy fold-over clamp (retainer). That's because those ones are too high and this neat little mounting solution won't work as the whole assembly will simply be too high to fit in the MKS-70's 2U case.

The other point to note is that the V02 mounting bracket puts the Vecoven PWM daughter-boards, in very close proximity of the voice-boards. Hence and unlike if mounting the Vecoven PWM daughter-boards to the voice-boards, vertical and NOT right-angle IDC headers must be fitted to the PWM boards.

I wasn't going to offer this bracket as an item as it didn't seem worth it but I've been persuaded to get some made up and so I’m selling them with fixing hardware (screws, washers, spacers), as a kit for 27.60 GBP. This includes tax but excludes shipping. 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!


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.

Taped mole grips to protect case
Doesn't look very pretty but helps protect your case.

When re-assembling, I would recommend replacing the nuts and soaking them in a lubricant like WD-40 prior to fitting.


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.
Roland MKS-70 Fully Upgraded
Boot screen of fully upgraded Roland MKS-70.


Live Forever battery mod at Plasma Music

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:

  1. Will last a lot longer than the standard CR2032 which is found in most synthesisers and effects processors.
  2. Mounted off-PCB so in the remote event that it does leak, sensitive electronics inside your equipment is protected.
  3. 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.


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 MKS-70 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! 😀

Ctrlr Panel for Vecoven Super-JX

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 MKS-70 upgrades (or JX-10 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: - This is Guy Wilkinson's website full of seriously useful information about the Roland Super-JX. - Sites like this, truly keep the legend alive! - An excellent reference site. - You just knew that there had to be a Facebook group, right? - ...or two!!!

Retroaktiv MPG-70 hardware Super-JX programmer

UPDATE: 11th July 2020

Wow! Since I put up this post, things have got a little busy.

Super-JX mods at Plasma Music
Three MKS-70s and yes, well done! You've spotted the MKS-80 in the foreground.
Super-JX mods and upgrades at Plasma Music
This machine is having my Super-JX upgrade bundle fitted.

UPDATE - 17th August 2021

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

Today I launched Nebula, a replacement jack-board for the MKS-70 with upgraded MIDI and balanced outputs.  Read all about it here.

UPDATE - 19th June 2022

I've been meaning to add this update for months so finally...

A few months ago, Fred Vecoven launched his digital PWM upgrade. It's brilliant! You can read more about it here.

Digital PWM installed on Super-JX Voice-Board
Simple and elegant, Fred Vecoven's new digital PWM upgrade for the Roland Super-JX is quite simply beautiful.




Simple and elegant, Fred Vecoven's new digital PWM upgrade for the Roland Super-JX is quite simply beautiful.


UPDATE - 19th January 2024

Over the past few days, I've been experimenting with replacing the wires that connect the module-boards to the jack-board, in the Roland MKS-70, with screened cables.

It's not as simple as it might sound. To start with, I needed a tool that cost over 400 GBP. I also needed to carefully consider some aspects of the original connection.

Screened audio cables for the Roland MKS-70
Perhaps the most boring thing I've ever photographed! My screened audio cables for the Roland MKS-70.

After some tests and experiments however, I'm delighted to announce that my screened audio cables for the Roland MKS-70 are now available in my e-store. You can read more about this easy to install upgrade, here.

Switched-mode power supply for Roland MKS-70
Guy Wilkinson's P0004 switched-mode power supply for Roland Super-JX.

Never thought I’d make a new friend over lock-down but I have recently struck up a relationship with Guy Wilkinson of

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 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 Wilkinson's Super-JX OLED upgrade module.
Guy Wilkinson's Super-JX OLED module. The background images show an actualSuper-JX OLED installed in a Roland MKS-70.

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.
    • 1 x insulating boot for IEC socket.
    • 2 x Pre-cut earth leads terminated at one with earth tag.*
    • 1 x M3 earth tag (for one side of IEC socket).

*One earth lead connects IEC earth to chassis via one of the screws that secures the IEC socket. The other earth lead connects the P0004 power supply to the chassis via any M3 screw.

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.
It is paramount that if fitted, a 2-pin IEC C10 mains socket be replaced with a 3-pin IEC C14 mains socket and that the chassis and the P0004 are connected to earth.


The IEC C14 socket that I use, is a drop-in replacement for the 2-pin IEC connector found on many Roland keyboards and rack modules. It is NOT necessary to drill, file, cut or modify the case to fit this IEC C14 socket.

A little known fact is that even keyboards with integral (hard-wired) power cables, have the power cable mounted to a metal bracket which is secured to the same screws holes and with the same type of screws, that are used on versions with IEC connectors! Behind that plate, is a cut-out for an IEC C14 connector.

Below is an image of the back of a Japanese JX-8P with a hard-wired power cable. You can clearly see that the cable goes into a cable gland which is in a very IEC C14 sized metal plate. T H A N K  Y O U, Roland!!!!

Power cable inlet on hard-wired JX-8P
Even a hard-wired power inlet can be fitted with an IEC C14 power connector WITHOUT having to do any drilling!

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!

Guy Wilkinson's switched-mode power supply installed into a Roland MKS-70
Look, no transformer! Coooool.

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.

Guy Wilkinson's OLED installed in MKS-70
Never knew what people meant when they referred to tech as "sexy". Now I do. I can't stop looking at it!!!!

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. 

UPDATE - 9th June 2022

I'm a big believer in the saying "If it ain't broke, don't fix it". On the other hand, isn't wisdom all about taking action before stuff goes wrong?

Today I had the most terrible job of telling a customer that the only way he's going to get his MKS-70 up 'n' running, is by acquiring a new assigner board. 🙁 That basically means buying a new MKS-70!

Yet another PSU failure and yet another totally scrapped MKS-70.

I can't emphasise this enough;


Look, there are two MASSIVE hidden bonuses when using something like Guy's P0004 power supply;

  • Unlike the original Roland PSU, the +5V supply on the P0004, is NOT derived from the +15V line and is fully independent. Hence, any fault on the +15V line, won’t affect the +5V supply.
  • In the event of a failure, the respective supply will simply stop working and chuck out 0V.

Big deal, so... Well, sadly, I occasionally see a MKS-70 which has had a failure of the +5V supply. If the failure is as a result of the +15V going wacky, this often results in the +15V line jumping to like +22V, thus maxing out the +5V regulator circuitry and taking out your assigner board. That’s basically a bricked MKS-70! 🙁