Sonic LAB: Korg MS20 Kit - Built and Modified

US Full-size flatpack synth replica      04/04/14
    MP4 18:2 mins    

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Last year the world went mad for the Korg MS20 Mini - a small scale reproduction of the classic analog monosynth, which by all accounts sells like hot cakes. Then at NAMM Korg introduced a full size, limited edition build it yourself MS20 Kit.

First major difference is that it's a much higher build quality, with everything bolted to to the front panel by 95 bolts (I should know, I tightened them all myself) it's a much sturdier machine. It's got the same electronics as the MS20 mini - including the USB/Midi interface, but with the addition of a selectable filter. The original MS20 had a rev 1 (Korg 35 chip) and rev 2 (LM13600) filter - the first was an angrier less refined design, the newer was smoother when fully resonant. These are selected by a three-pin jumper on the circuit board. Our first task was to attach  a switch to make it selectable externally. But first we had to build it...


Opening up the box it becomes clear pretty quickly that this is more of a self assemble project than a full DIY affair. We're talking screws, attaching some circuit board connectors and a LOT of nuts.

As you take out the tightly packed case parts and fully assembled circuit boards, it's does seem like a heck of a lot of stuff and at first appears a bit daunting. Though be comforted in the knowledge that while electronics boffins may be disappointed at the simplicity of the build, the novice should be able to take it on without distress.

Will It Bend?

The answer appears to be wholeheartedly yes, though please don't rely purely on my non-existent grasp of electronics. We modified the filter selection to be externally selectable with three wires and a switch, there are also many points labelled on the board for PWM, Osc Sync, individual filter and OSC outputs and more. Though I suspect you may have to start cutting holes in the case to access all of this stuff, it's most welcome (PWM especially).

The Build

I'm no stranger to flat pack, and this was no different, the instructions while occasionally puzzling, get you there with the application of some common sense. You would have to try fairly hard to break anything, with most operations simply a matter of lining up and screwing something in. The only tool provided is the spanner for the nuts, the rest can be done with a Philips (crosshead) screwdriver - absolutely no soldering needed.

Did It Work?

Well yes, even I managed it, we timed it at around 1hr 45 mins (not including a tea break). I took a couple of wrong turns - put the keyboard in the wrong way round and had trouble locating the foil end pieces. But at the moment of truth - when I plugged the external power supply in (the other deviation from the original) it powered up!

One other thing, the power will auto shut off if left on for a while - this I believe is a new EU eco power saving directive for all new electronic gear - but it worried me for a moment.


It does sound damn close to my MS20 original - given that its electronics are 30+ years old. I think I also now know I have the late style filter in mine, it seemed the closest - though the resonance kicks in earlier on my old girl. I was pleased to hear that there is a noticeable difference between the late and early filters when switching between them - the later one is smoother and less extreme, especially at high resonance settings on both LP and HP filters.

Paint Job

I noticed in the comments for the full timelapse video we posted, that there were questions about the paint work - some people have reported flaking of the white paint. I can unfortunately confirm that our MS20 kit also suffered from the patchbay area losing some of the white printed paint. This is a damn shame, and something that really should not happen. I would suggest a coat of some tough matt varnish or similar (you would need to research that). It would of course delay the final build - but believe me, you do not want to unscrew all those nuts.

Would You?

I guess, given that there are a number of options at this sort of price (£1000 UK, $1399 US) you have to ask yourself if you would - the more cynical might say "I have to build it myself and pay a premium?". Well yes, this is true, but it's a damn near perfect facsimile of an original MS20, for which one would expect to somewhere around twice the price.

Added to that it's a limited edition instrument and so does have a certain exclusivity.

I do wonder why Korg didn't include the filter selection switch as an option, perhaps a grommet on the panel to bolt it in if desired.

NOTE: it is possible to switch filters by a combination of notes (F#3, G#3 and A#3  for older, and F#3, G#3 and B3 for later filter) on power-up. It reverts to the hardware switch with no powerup modification.

The only real fly in the ointment for me is the issue with the paint, aside from that the build quality is solid (I should know, I built it...)

Limited edition - only 1000 available. £1079/ $1399

Available from local Korg dealers.


FYI Filter Mod Info

Its pretty simple, you just need a single pole, double throw switch, three wires and a Phobya 3 pin connector:
We used an old CPU fan power cable which had three wires and a connector. Then just wired up the centre pin to centre, each side to the outer pins of the switch -



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