For Sale: Original Korg MS-20

The Korg MS-20 is a classic semi-modular monophonic analog synthesizer released by Korg in the late 1970s (1978), designed with the concept of “a wall on your desktop.” It emphasized providing modular-synth-like patching freedom at a relatively affordable price.

It uses a hard-wired (pre-patched) + patchable design: it can produce sound without any patch cables for normal use, but the right-side patch panel (35 x 6.35mm / 1/4” jacks) allows complete signal rerouting, enabling sound design far beyond typical synthesizers. It’s often called the “poor man’s ARP 2600.”

Core Specifications & Features (purely original 1978 version characteristics, excluding later Mini/Kit/FS revisions)

•  Keyboard: 37 keys (C–C, three octaves), full-size keys (not mini)

•  Polyphony: Monophonic

•  Oscillators ×2 (VCO)

•  VCO1: Triangle wave, sawtooth wave, square wave (with adjustable pulse width PWM), pink noise, white noise

•  VCO2: Sawtooth wave, square wave, narrow pulse wave

•  Built-in Ring Modulator between the two VCOs, capable of producing metallic, bell-like, or extremely dissonant sounds

•  Coarse/fine frequency tuning, Scale adjustment (can intentionally create non-equal-tempered or chaotic scales)

•  Filters ×2 (in series — the true soul of the MS-20)

•  High Pass Filter (12dB/oct) + Low Pass Filter (12dB/oct)

•  Both filters have extremely strong self-oscillation capability (max resonance produces near-sine-wave screaming tones)

•  Uses the famous early Korg-35 filter chip, with extreme characteristics: very aggressive resonance, easy overload/distortion, rough scraping texture, ferocious low-end punch, piercing sharp highs

•  This filter pair is widely regarded as one of the most aggressive and characterful in synth history

•  Amplifiers ×2 (VCA)

•  VCA1: Primarily controls keyboard-triggered volume

•  VCA2: Often patched for additional modulation or external signal processing

•  Envelope Generators ×2 (EG)

•  EG1: Hold + Decay (ideal for controlling filter sweeps or percussion-like hits)

•  EG2: ADSR (standard envelope, mainly controls VCA volume)

•  Very wide time ranges, from ultra-short attacks to extremely long releases

•  Modulation Generator (MG = LFO)

•  Waveforms: Square wave + adjustable-shape triangle/sawtooth mix

•  Extremely wide frequency range: from ultra-slow (tens of seconds per cycle) to audio-rate (usable for audio-rate FM/AM)

•  Two independent outputs: one pulse, one ramp/slope

•  Other Built-in Sources

•  Noise generator (white noise + pink noise)

•  Sample & Hold (commonly patched with noise for random stepped sequences)

•  External Signal Processor (ESP) — extremely powerful feature

•  Accepts external audio input (microphone, guitar, drum machine, etc.)

•  Auto pitch detection → outputs CV to control VCO pitch (similar to a simple vocoder/follower)

•  Envelope follower (tracks input volume) → can control filters or VCA

•  Trigger detection → triggers internal EGs

•  Turns the MS-20 into a “voice transformer,” filtered guitar processor, drum-triggered synth, etc.

•  Patch Panel (35 x 6.35mm / 1/4” jacks)

•  Includes inputs/outputs for all major signals: Keyboard CV/Gate, VCO pitch/freq mod, VCF cutoff mod, VCA gain control, EG outputs, MG outputs, S/H, Noise, Ring Mod output, various ESP outputs, etc.

•  Example patch ideas:

•  MG → VCO pitch → crazy vibrato/LFO pitch sweeps

•  EG → VCO PWM → wah-wah dynamic pulses

•  Noise → S/H → random CV to filter or pitch

•  VCO square wave → self-oscillating filter → industrial screaming

•  External drum → ESP trigger → EG filter sweep

•  VCO1 → Ring Mod → VCO2 → extreme metallic tones

Sound Character Summary (unique or most pronounced in the original)

•  Extremely raw, dirty, and overloaded (especially the early Korg-35 filter)

•  Filter becomes particularly vicious at high resonance, easily producing strong distortion and gritty scraping textures

•  Huge dynamic range, thick heavy lows, razor-sharp highs — very industrial/experimental/aggressive vibe

•  More “raw” and unstable than later Mini versions (oscillators can drift slightly), but this gives it a more “alive” analog feel

•  No MIDI, no USB, no built-in effects — pure analog hardware

The charm of the original MS-20 lies in its “imperfections” and “extremes”: ferocious filter, high patching freedom, raw wild sound — it’s a direct representative of late-70s to 80s industrial, noise, and early electronic music tones.

Famous Patch Example: Classic Acid Bass / TB-303-style Acid Bass (one of the most iconic — essential for industrial/acid techno)

•  Characteristics: Raw, gliding, heavily resonant sweeping acid bass; the MS-20 filter is naturally perfect for this.

•  Key Patch:

•  EG1 Out → LPF Cutoff Freq

•  EG1 Rev Out → HPF Cutoff Freq (reverse sweep: high-pass opens as low-pass closes)

•  (Common) MG square → slight VCO pitch mod, or keyboard CV → VCO

•  Settings Tips:

•  VCO1: Square wave; VCO2: Ring mod or square wave

•  Resonance extremely high (8-10), LPF cutoff low (2-4), HPF medium-high

•  EG1: Attack 0, Decay 3-6; EG2 controls volume

•  Turn on a bit of Portamento for classic glide/slide

•  Many people call this one of the MS-20’s “most classic” signature sounds.

100v Version

We accommodate different regions by supplying the correct power transformer according to your local voltage (e.g., 110-120V or 220-240V).