Korg MS-20 – the semi-modular revolution

The Korg MS-20 synthesizer was released in 1978. This landmark indicated to American synthesizer manufacturers the coming dominant factor in the synthesizer field: Japan.

In its brief life span (production stopped in 1983), there were more than 20,000 (!) MS-20 sold. Monophonic ARPs and MOOGs and even the very popular Sequential Pro-One could only dream of such numbers!

Korg MS-20

Korg MS-20

Due to its semi-modular concept and integrated patchfield, the MS-20 is also known as “the poor man’s ARP 2600”.

“A budget classic – the poor man’s ARP 2600. Probably a good half of the facilities – at a quarter of the price – although that’s starting to creep up to a third of the price as the MS-20’a popularity grows rapidly.”

(Peter Forrest: The A-Z Of Analogue Synthesisers)

Korg MS-20

Korg MS-20

Let’s start by comparing these two instruments. While sound programming and patching, in particular, is done quite easily on the ARP 2600 (thanks to its clear layout and logical overall concept), musicians trying to do the same on the MS-20 could get pretty desperate …

Chaos dominates the MS-20 patchbay, which is surely the most confusing patchbay on a commercially-produced market synthesizer. Am I exaggerating? Maybe. But I think it’s impossible to combine, while playing, the MS-20 pre-patched signal and the puzzling patch area in realtime. Simple routine-modulations might work, but don’t try patching a dozen cables …

Korg MS-20

MS-20 keyboard

So “poor man” could also mean “poor musician” …!

Concept of the “Small ARP 2600”

“A maximum of features at a very low price”… That might have been Korg’s philosophy when constructing the dual-oscillator MS-20 synthesizer. Maybe it didn’t mutate into an ARP 2600, but it is a sort of a cut-down version of the gorgeous PS-3100. Some people even say its predecessor is the small Korg 770. My ears tell me the MS-20 comes closer to a PS-3100 than to a 770 …

Korg Family

Part of the Korg family, 1978

As soon as we leave the conceptional discussion and have a look at musical flexibility, that nice ARP 2600 is no bad comparison. Korg’s MS-20 offers heaps of features, including 2 VCOs plus ringmodulator, 2 VCFs, S/H, noise etc. All these beauties, combined with a versatile patch field, has let the MS-20 become one of the most interesting FX-soundmachines. In some ways its potential for musical expression isn’t far from an ARP 2600.

The following table provides a components list for both instruments:

Korg MS-20 ARP 2600
VCO 2 3  (switchable to low frequ)
LFO 1 1  (3620 keyboard only)
VCF 12dB LowPass
12dB HighPass
24dB LowPass
Delay + AR
VCA 2 2
Noise White Noise
Pink Noise
White Noise
Pink Noise
Low Frequ
Extras Ringmodulator
Ext. Signal Prozessor / Envelope Follower
Sample & Hold
Assign. Wheel

Microphone (Ext In) PreAmp /
Envelope Follower
Sample & Hold
Portamento (3604 + 3620 keyboard)
Pitch Bend Knob (3604 + 3620 keyboard)
3x Voltage Processors
Lag Processor
Electronic Switch
Spring Reverb

To sum it up: the association of MS-20 with ARP 2600 is not as far out as it may seem. The equipment and concepts of the two instruments are very similar.

Korg MS-20

Korg MS-20 and ARP 2600


As a pre-patched synthesizer the MS-20 offers:

2 VCOs

  • VCO1 – triangle, saw, pulse, noise. Range 32′ to 4′
  • VCO2 – saw, pulse 1, pulse 2, ringmodulator. Range 16′ to 2′

VCO Mixer – just to let you know: one single VCO sometimes sounds brilliant ..!
2 VCFs
– with individual CV inputs. Combining both filter results in BandPass, sounds great!

  • HPF (with resonance)
  • LPF (with resonance)

LFO (triangle, saw, pulse)
2 ENVs

  • ADSR (+ hold function)
  • AR (+ extra delay)

VCA 1 (+ external CV input)
External Signal Processor
Trigger Button
Master Tune

Korg MS-20

MS-20 patch panel

The following features are offered via the patch panel:

VCA 2 (+ external CV input)
S/H generator (with external clock input)
ENV 1/2 reverse output
Pink & White Noise

Those features are quite impressive, aren’t they?

I forgot one rather dubious “highlight”: the 3-octave keyboard is a nightmare! Some MS-20 keyboards are so clunky and noisy you need headphones to hear the music above the din of the keyboard. Modern expressionists and “very” modern artists could assert that disturbing noises are part of the desired result … The MS-20 keyboard is one of the cheapest constructions ever made, although I must admit, Roland keyboards of the late 70s were even worse. They didn’t rattle that much, but they (and we) suffered from double trigger problems. And yes … the Formanta Polyvoks keyboard is even much (!) worse, of course.

The Filter(s) – acoustic fingerprint of the MS-20

You are right: the MS-20 offers two filter sections. But when talking about “the” MS-sound, people generally have its wonderful 12dB low pass filter with dirty resonance in mind. It’s sort of an acoustic fingerprint of the MS-20, a distinctive source of unique sounds.

Korg MS-20

MS-20 filter compartment

Even comparing the LPF with other Korg synthesizers, it’s in a class of its own. The MS-50 has a different filter sound, as does the huge PS-3100 – but on those instruments less aggressive resonance, less dirty sound variations are possible.

It is also noteworthy that the quality of the filter sound can vary greatly from model to model. I have had three units of this synthesizer over the years, but just one model was really “a cracker”. The other two MS-20 were OK, but not that unique. Why? I don’t know. Maybe there really were an early and a late MS-series, as wild speculations claim.

But then such speculations are often an attempt to justify unnecessarily high prices by claiming the instruments in question are part of a specific, rare series.

Although the 12dB low pass filter is certainly the most characteristic feature of the Korg MS-series (MS-10, MS-20 and MS-50 use it), it’s the 12dB high pass filter which makes the Korg MS-20 so special.

Korg MS-20

Korg MS-20

“Having a genuine voltage-controlled high-pass filter with ‘peak’ (resonance) is a good bonus, and is important in producing a lot of the MS-20’s most characteristic sounds.” (Peter Forrest: “The A-Z to Analogue Synthesisers”)

In any case, the MS-20 filter seems to be in vogue again. Korg uses the low pass filter in its new Monotribe. Of course, a filter and a VCO (Monotribe, for instance) don’t make a full-fledged MS-20 (not even an MS-10), but I must admit: The Monotribe has a seductive, lively and very, very fresh sound. More about this later.

Sound and Performance

Never underrate the MS-20! (And don’t even think that any modern MS-20 re-issue – even if it was released by Korg themselves – comes close the sound of the original.) Let’s take a look at the MS-20 sound potential …

First, its position as superb sound machine for FX tones is – in my personal opinion – unchallenged!

Second, bass sounds are not bad! Sadly VCO 2 ends at 16′ while VCO 1 goes down to 32′. Well, you need to be a little creative: use the Frequency Modulation MG/T.EXT knob (and patch the wheel to the VCO’s FREQU input) and transpose both oscillators one octave down. Then adjust each VCO at 16′ – as soon as you play the keyboard, they both sound at 32′. Quite simple, I know. You even could go further and turn VCO1 to 32′, while it sounds at 64’… but I guess that’s where it starts acting as a low frequency oscillator.

Korg MS-20

MS-20 oscillator scaling

Sure, IF there was a 4-octave keyboard, no one would argue about transposing problems – but there isn’t. So, again, maybe you can make a case for the “poor man’s ARP 2600”.

Third, lead sounds profit from the wonderful filter constellation. Full of character the LowPass and separate HighPass (with extra resonance!). Together they act as a BandPass filter – not bad! The cutting sound character, combined with the short envelopes (“percussive release” is probably the nearest to it, even if, technically speaking, no such musical term exists) brings out tasty timbres similar to Yamahas early polyphonic CS-synthesizers CS-40M and CS-20M, respectively. Maybe the sound character differs, but the sound behaviour is in all three cases very much the same.

Last but not least: the patchable single wheel on the MS-20 is another strong point. Nice soli and inspiring melodies are not that difficult to produce with brilliant performance options, etc.

Korg MS-20

MS-20 single modulation wheel

Fourth, subtle tones are one of the unknown strengths of a Korg MS-20. Whether they belong to the FX-area or to the lead sound section… most musicians will be immediately convinced. Quite a few of the sensitive fx-sounds are very similar to the ARP-2600! It may take some time to get to the bottom of those sound creations, but in principle they are possible.As usual, there are three golden rules for producing one’s own sounds:

  • First, be patient. Discovering the ideal filter- and envelope-adjustments takes time.
  • Second, use the whole instrument. No MS-20 is complete if you leave out its patchbay. You may occasionally end up in a confusing patch-orgy, but you’re just as likely to come up with brand new, excellent modulation sounds.
  • Third, less is more. Using all the oscillators, all filters, the internal LFO plus some external ones; modulating the instrument via wheel and analogue sequencers at the same time; investing all to do your very best is no guarantee for unique, interesting sounds full of character. Less is more. Start with one VCO. Use the dull sounding triangle wave. Run it through one filter and experiment with resonance effects and modulation possibilities, sensitive adjustment of attack time, etc. Give it a try! Sometimes surprising sound impressions are based on very simple constructions.
Korg MS-20

MS-20 patch panel detail: Ext Signal In

Korg Legacy Collection and MS-2000 – virtual synthesizers

Just a few words about these instruments. Since a couple of years, the MS-20 is available as software synthesizer. Part of the Korg Legacy Collection, it came with a dedicated MS-20 USB controller – a small replica of the original MS-20 with a mini-keyboard and patchbay. (But even if it looks nice – after all it is nothing more than software, right?) The Korg MS-2000, however, is a 4-voice virtual analog synthesizer based on the MS-10/20 and Monopoly. It came out in 2000 as a competitor to Clavia’s NordLead and Roland’s JP-8000.

Monotribe – small analog workstation with MS-filter

As generally known, Korg has turned again to analog synthesizers in recent years. They’re very small. The Monotron from 2010, for instance, looks like the remote control of an electric garage door. Costing point: a dinner for one. Its “big” brother, the Monotribe followed in 2011. Korg is currently in business again with the MS-20 low pass filter – something that was actually designed 20 years ago.

Let’s face it, the sound of the Monotribe is not comparable to the MS-20 of those golden days. Nonetheless, the Monotribe has its very good points. Its concept (the combination of funky analog sounds with sequencer and drum loops) is inspiring and quite excellent. You might get addicted …

Korg Monotribr

Korg Monotribe with MS-10/20 lowpass filter

Historically, the current trend is very interesting. If “workstation” were a term applicable to the monophonic synthesizer field, it would go a long way toward describing the marvellous MS-synthesizers (or say: MS-family) in 1978. However, the MS-20 was missing an on-board sequencer and/or arpeggiator, which is why Korg released the SQ-10. It was (and still is) a perfect match for the MS-20.

The circle has now been completed to that “idea” of an affordable workstation. In essence, such an analog package is back again in the new Monotribe. The package is even supplemented with a simple, on-board drum machine à la TR-808 (reduced to three sounds: bassdrum, snare, hi-hat) …

MS-20 today

In 1978, Korg’s MS-20 was a hot potato. It has remained a very popular and unique music instrument up to this day. Many people fell in love with it due to a unique filter design, due to modular options, due to its unusual (maybe brilliant?) analogue sound character. Both professionals and home studios use this beauty nowadays. It’s one of the most important synthesizers available regularly on the vintage market. Sure, it’s gotten to be a bit expensive. 1,000 – 1,500 Euros/Dollars is far too much for a little old analogue synthesizer. Or is it?

Korg MS-20

Korg MS-20

After all, there are alternatives in that price region. The Doepfer A-100 modular system, for example, starting from 1700 Euros (basic system). Or a comparable instrument from Analogue Systems (I really love the RS-200 sequencer, by the way) or Analogue Solutions. Any of these modular systems has much more sound potential than the semi-modular MS-20.

But certainly, it’s up to you. Making the right decision is actually easy: look at the MS-20 features, listen to those powerful sounds, imagine its versatile modulation routings, etc. Then sit down, have a cup of coffee (or some tea!) and decide whether or not this ingenious musical instrument is worth its currently high price.

Filed under 2012, Reviews

“Es genügt, einen Ton schön zu spielen” sagte der Komponist Arvo Pärt im Jahre 2005. Diese Aussage ist ebenso einfach wie ich auch exzellent: Es braucht kein Meer an Tönen, denn entscheidend ist der Klang. Dass so mancher Vintage-Synthesizer der 70er und 80er Jahre teils unerreicht hochwertige Klänge liefert, steht außer Frage. Doch tatsächlich leben wir “heute” in einer nahezu perfekten Zeit. Einerseits hat man – mehr oder weniger – noch Zugriff auf die Vintage Analogen, andererseits wird auch bei Neugeräten die wichtige Komponente des hochwertigen Klanges wieder zunehmend berücksichtigt. Doepfer, Cwejman, Synthesizers.com, MacBeth, Moog, GRP, Studio Electronics, COTK, John Bowen und andere Hersteller bauen hervorragende Synthesizer, die den “Klassikern” in nichts nachstehen. All diesen (alten wie neuen) “großartigen” Instrumenten ist Great Synthesizers gewidmet. _________________________________________________________ In 2005 composer Arvo Pärt said: “Playing one tone really well is enough”. In other words, it is sufficient to play one tone 'beautifully'. I agree with that. All musical efforts are focused on the sound itself. Although I studied classical music (piano and drums), it’s the electronic sound that inspires me. Synthesizers are the epitome of new sounds and exciting tonal spheres. Today, many companies produce high-quality - excellent! - synthesizers: Doepfer, Cwejman, MacBeth, Moog, GRP, Synthesizers.com, COTK, Studio Electronics, John Bowen and others. It's their products I'm really interested in ... apart from Vintage Synthesizers, which I have been collecting for 20 years. Subsequent to our former websites Bluesynths and Blogasys, Peter Mahr and I have now created GreatSynthesizers. We hope you like it.


  1. Mads Gelting

    Excellent writeup.
    It would be interesting to see a review of the New MS20 mini to see just how it compares to the original.

  2. Hi Theo!
    Great as always! Just one Q. Did you used old, Korg 35 version for this demo and have you ever compared later version sound wise?

  3. Theo Bloderer

    Hi Miro … in these demos, I used the “old” MS-20. Do have both versions and like the early bird more. If it’s just that particular model or the whole bunch of “old” MS-20 that sounds better, I don’t know …

  4. Hi there are no speculation on early and late models. The early one have the korg 35 filter and the late a on board filter. They really don’t sound the same. Some prefer the late and other the early one. I have the early one and really refer it : )

  5. You’re confusing the MS-20 “Mini” (which is a FULL reproduction of the MS-20 and can be played without a computer) with the MS20 “Legacy Controller” which required the Korg Legacy software to be loaded into a computer or tablet and required to be connected to said device. Suggest you do some more research, https://www.soundonsound.com/reviews/korg-ms20-mini

  6. Theo Bloderer

    … hello Mike … I see no confusion here. MS-20 “Original” / “Legacy Controller” / “Mini” – it’s all clear. But thanks for the link – I will add it to the review. Cheers …

  7. Mark Pigott

    The Monotribe can be made to punch above its weight with a few simple mods.
    On the 6 I own I have done the following to 5 of them

    a)Input to the filter CV by tapping the middle lug on the cutoff pot and sending to an 1/8″ jack
    external CV via a 12k resistor.

    b)VCO square mute. I have a shorting 1/8″ jack, that when square is selected the VCO is muted.
    This allows externally filtering without the VCO of external signals. When I plug into this jack,
    I break the normal and have external square to output of external gear.

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