Korg MS-20 V

How it works

It is a subtractive semi-modular: the modules are already wired internally in a standard path (you play without cables), but a patch bay lets you break or add connections with virtual cables.

The basic path

Two VCOs → mixer → resonant high-pass filter → resonant low-pass filter → VCA. EG2 controls volume and filters, EG1 controls pitch and the speed of the Modulation Generator (MG, Korg's name for the LFO).

Control voltages (CV)

Every module has inputs that accept voltages: a voltage on FREQ changes the pitch, on CUTOFF the cutoff, on the VCA the volume. A source (MG, envelope, keyboard, S&H, noise, sequencer, even an audio output) connected with a cable to an input becomes a modulation. The MG/EXT and EG/EXT knobs set how much that modulation acts.

The character

The MS-20 filter is designed with very few components: with high resonance the signal saturates and “screams”, especially when the input sound is loud. You can also send an external signal (voice, guitar, drums) into the External Signal Processor, which extracts pitch, envelope and triggers to make the synth play or to filter it.

Character and tone

Timbre

Raw, growling and alive: two simple VCOs and two filters in series (high-pass and low-pass) with a resonance that whistles and saturates in an unmistakable way. The MK1 (Korg 35) filter is rawer and dirtier, with less sub; the MK2 (OTA) has more bass and a cleaner, “screaming” resonance.

Where it sits in the spectrum

Sharp in the upper mids (1–5 kHz) when the resonance is high, but with a firm bass if the high-pass stays open. The resonant high-pass allows thin, nasal sounds that cut through the mix.

Strengths

• Aggressive resonance and series filters that can be modulated together or separately (Link).
• Semi-modular: it plays without cables, but the patch bay opens up cross-modulation, S&H, VCA, feedback, ESP.
• EG1 with Delay/Attack/Release, EG2 with Hold: unusual and very musical envelopes.
• In the Arturia version: polyphony, unison, PWM, 12-step 3-channel sequencer, 16 effects.

Limitations

• Essential oscillators (no fine detune on VCO1, VCO2 with a ±13 semitone range).
• Not a very “elegant” sound: refined pads are not its territory.
• MK1 in polyphony is CPU-heavy.

Comparisons

• vs ARP 2600: both semi-modular, but the 2600 is cleaner and more lab-like; the MS-20 dirtier and more aggressive.
• vs Minimoog: the Moog is round and warm, the MS-20 sharp and scratchy.
• vs TB-303: both for acid, but the MS-20 is rougher and more versatile, the 303 more “squish” and tied to its sequencer.

Architecture

Original (Korg MS-20, 1978–1983)

• Monophonic, 2 VCOs: VCO 1 triangle, saw, variable pulse, white noise; VCO 2 saw, square, narrow pulse, ring modulation.
• Resonant HPF + LPF in series (Korg 35 in the early series, later a softer OTA circuit).
• EG1 (Delay, Attack, Release) and EG2 (Hold, Attack, Decay, Sustain, Release); MG with variable waveform (triangle/saw/ramp and variable duty-cycle pulse).
• Patch panel with S&H (actually track & hold), VCA, white/pink noise, patchable wheel and momentary switch, External Signal Processor (amplifier, band-pass, frequency-to-voltage converter, envelope, trigger).

Signal path

VCO 1 + VCO 2 → mixer (+ External In) → HPF → LPF → VCA (EG2) → Signal Out; modulations from MG, EG1, EG2, KBD, wheel, patch.

What Arturia adds (Korg MS-20 V, V Collection 9)

• Polyphony and Unison (up to several voices with detune 0.1–100%), Note Priority, Voice Allocation Reassign/Cycle, MPE.
• PWM of VCO 1 (MG/EXT), EG1 modulation assignable to VCO 1, VCO 2 or both (FM assign), VCO audio outputs, Master In, Signal Out.
• MK1 / MK2 selector, cutoff Link (same direction, opposite, off).
• EG1 with Trig/Gate/Loop mode; EG2 with Classic/Modern range and Decay Curve; Cutoff Mod Sidechain (velocity) and Amplifier Modulation.
• MIDI patch points: VEL CV OUT, AFTER CV OUT, separate inputs for tracking and trigger, unlimited mults.
• Analog 12-step 3-channel sequencer (A, B, C) with swing, gate, portamento and CV outputs.
• Effects: 3 slots (series/parallel) with 16 effects.
• Dispersion with 6 trimmers (under the Korg logo).

The controls, one by one

VCO 1

Waveform

Triangle, sawtooth, variable-width pulse, white noise.

PW

Pulse width from 50% (square) to 0% (silence); it also subtly affects the triangle.

Scale

32', 16', 8', 4'.

VCO 2

Waveform

Sawtooth, square, narrow pulse, ring modulation (VCO 1 × VCO 2: sum and difference frequencies).

Pitch

Interval relative to VCO 1 from -13 to +13 semitones, finer near zero (double-click = 0).

Scale

16', 8', 4', 2' (one octave above the VCO 1 range).

Oscillator switches

VCO 1 > VCO 2 Sync

VCO 1 restarts at every cycle of VCO 2 (Arturia addition): modulating VCO 2 gives sync sweeps.

Unison

Several voices on the same note in Mono Legato/Retrig; number of voices and detune in the bottom bar.

VCO Mixer

VCO 1 level / VCO 2 level

Levels of the two oscillators into the filters: high levels make the filter saturate (grit).

Pitch Modulation

Portamento

Glide from 4 ms to 2.57 s.

Frequency Modulation MG/T.EXT

Amount of MG (or of the signal in the TOTAL jack) on the pitch: vibrato, trills, sirens.

Frequency Modulation EG1/EXT

Amount of EG1 (or of the FREQ jack) on the pitch: pitch sweep, zap, kick.

FM assign (VCO 1 / VCO 2 / both)

Which oscillator receives the EG1/EXT modulation: modulating only VCO 2 gives single-oscillator FM or sync sweeps.

Pulse Width Modulation

PW Modulation MG/EXT

Amount of PWM from the MG or from the PWM IN jack (Arturia addition).

Filter Section

Highpass Cutoff Frequency

High-pass cutoff (at the bottom = no cut).

Highpass Peak

High-pass resonance: nasal, 'telephone' sounds, whistles.

Lowpass Cutoff Frequency

Low-pass cutoff.

Lowpass Peak

Low-pass resonance, up to screaming and self-oscillation.

Link

Links the two cutoffs: same direction (band sweep), opposite direction (widens/narrows the band) or 0 (independent).

MK1 / MK2

MK1 = Korg 35: less sub, more noise, raw and scratchy in distortion. MK2 = OTA: more sub, cleaner and more screaming resonance, less CPU.

HPF Cutoff Modulation MG/T.EXT

Amount of MG/TOTAL on the high-pass.

HPF Cutoff Modulation EG2/EXT

Amount of EG2 (or of the dedicated jack) on the high-pass.

LPF Cutoff Modulation MG/T.EXT

Amount of MG/TOTAL on the low-pass.

LPF Cutoff Modulation EG2/EXT

Amount of EG2 (or of the dedicated jack) on the low-pass.

Modulation Generator (MG)

Free / Reset

Free: runs free (like the original); Reset: restarts on every note (noticeable in polyphony).

Waveform

Continuous shape: the triangle output morphs from saw to triangle to ramp, the pulse output from narrow to square to inverted narrow.

Frequency + Sync (musical note value)

From 0.093 to 17.8 Hz or synced (straight, triplets, dotted) from 8 bars to 1/32; red LED when sync is active.

EG1/EXT

Modulation of the MG speed from EG1 or from an external CV (vibrato that speeds up).

Envelope Generator 1

Delay Time

Delay before the attack, from 0 to 13.3 s.

Attack Time

From 3 ms to 60.8 s.

Release Time

From 51 ms to 70.4 s; between attack and release it stays at maximum.

Trig / Gate / Loop

Trig: full cycle at every key; Gate: like the original (holds as long as you press); Loop: repeats like a second MG.

Hard-wired destinations

Pitch Modulation, MG frequency, patch bay VCA; OUT and REV OUT outputs.

Envelope Generator 2

Hold Time (Classic)

Time the envelope stays at sustain after the key is released, before the Release (0–29.8 s): useful as an extended gate.

Decay Curve (Modern)

In Modern mode it replaces Hold: decay curve from -20 to +20 (default -4); negative = percussive, positive = soft or 'two-step'.

Attack Time

Classic 24 ms–14 s; Modern 1 ms–20 s.

Decay Time

Classic 32 ms–16 s; Modern 1 ms–20 s.

Sustain Level

Held level.

Release Time

Classic 30 ms–25 s; Modern 1 ms–20 s.

Classic / Modern

Original time ranges or wider and faster ones (truly instantaneous attacks).

Hard-wired destinations

Main VCA and cutoff of both filters; OUT and REV OUT outputs (negative).

Cutoff Mod Sidechain and Amplifier Modulation

Cutoff Mod Sidechain

Velocity → cutoff of both filters (brighter notes when playing hard).

Amplifier Modulation

Overall level modulated by the MG (tremolo) or by a CV in the EG2 Sidechain input.

Patch Panel: signal chain

TOTAL

Input that modulates VCO 1+2, HPF and LPF together (amount with the MG/T.EXT knobs).

PWM IN

CV for the pulse width of VCO 1.

FREQ

CV for the pitch of both VCOs.

EXTERNAL IN

Audio input into the mixer before the filters; also for feedback (Signal Out → External In).

HP / LP CUTOFF FREQ (CV in)

Separate modulation inputs for the two filters.

EG2 SIDECHAIN

CV that modulates the EG2 levels.

VCO 1 OUT / VCO 2 OUT / SIGNAL OUT / MASTER IN

Audio outputs of the oscillators and of the final signal, master input.

Master Tune / Volume

Tuning and master volume.

Patch Panel: MG and EG

MG triangle OUT (bipolar) / pulse OUT (unipolar) / Freq CV IN

MG outputs and control input for its speed.

EG1 OUT / REV OUT

Normal and inverted output (positive unipolar).

EG2 OUT / REV OUT

Normal and inverted output (negative).

Patch Panel: keyboard and controls

KBD CV OUT / TRIG OUT

Note voltage and trigger at every key.

VCO 1+2 CV IN / VCO2 CV IN / TRIG IN / EG1 TRIG IN

Inputs to drive pitch and trigger from other sources (e.g. sequencer, ESP).

VEL CV OUT / AFTER CV OUT

Velocity and aftertouch as patchable voltages.

WHEEL / MOMENTARY SWITCH / EXT OUT

Outputs of the wheel (if not patched it gives ±1 semitone vibrato with CC1) and of the momentary button.

Patch Panel: utility

Sample & Hold: IN, CLOCK, OUT

Actually track & hold: it follows the input while the clock is high and freezes it when it falls. Noise in IN + MG pulse in CLOCK = random values.

VCA: IN, CONTROL INPUT, OUT

Patchable VCA for audio or CV (e.g. attenuating an LFO with an envelope).

Noise Generator: Pink / White

Noise as audio or as CV.

External Signal Processor

SIGNAL IN + Signal Level

Input and preamplification of the external signal.

Low Cut Freq / High Cut Freq

Band-pass that cleans up the extremes before analysis; outputs after the amplifier and after the filter.

F-V Converter: CV Adjust / F-V CV OUT

Extracts the pitch of the signal as CV (to be sent to VCO 1+2 CV IN).

Envelope Follower: ENV OUT

Voltage that follows the volume of the signal.

Threshold Level / TRIG OUT

Threshold above which a trigger fires to play notes.

Dispersion (under the KORG logo)

6 trimmers

Pitch stability, PW uniformity, envelope parameters, cutoff, resonance, modulation stability (0 perfect, 1 unstable); especially useful in polyphony.

Sequencer Panel

Voltage Controlled Clock Generator + Sync + Power

Speed 0.1–100 Hz or tempo-synced (8 bars–1/32); power.

Clock Speed Modulation

External modulation of the clock speed.

Sequence Mode

A+B+C (three parallel channels) or AB+C (A and B chained), each Loop, Loop Retrig or Single.

Sequence Length

1–12 steps (double-click = 8).

Swing

From 50% to 75% (67% is the classic swing).

Gate

Note length per step from 5% to 95%.

Portamento A/B and C

Glide times 0.01–2.82 s, applied to the steps with the button on.

CV Mapping (knob per step)

-5/+5 value of each step.

Channel Range

A and B: ±1 V or ±5 V; C: ±5 V or Pitch (±12 quantized semitones).

Portamento Channel C / Trigger (buttons per step)

Glide and trigger active for each step (syncopated patterns).

CV OUT A / B / C, TRIG OUT EG1+2

Patchable outputs; without cables C controls the pitch (transposable from the keyboard) and the triggers play the envelopes.

Effects Panel

Routing, Presets, Copy, Sync, Dry/Wet

Three series/parallel slots with 16 effects: Delay, Tape Echo, Pitch Shift Delay, Reverb, Distortion, Bitcrusher, Compressor, Multiband, Chorus, Chorus JUN-6, Stereo Pan, Phaser, Flanger, BL-20 Flanger, Multi Filter, Parametric Equalizer.

Side Panel: Settings

MIDI Channels

Channel or All.

Poly mode

Mono Retrig, Mono Legato or Poly (the original is Mono Legato with high priority).

Note Priority

Low, High, Last.

Voice Allocation

Reassign or Cycle in polyphony.

MPE + MPE Slide 1/2

Per-note expression.

Sound design tips

Filters

• Resonance and input level: the “screaming” character also depends on how hard you push the VCOs in the mixer: high levels + high Peak = saturation and grit; low levels = cleaner, whistling resonance.
• MK1 vs MK2: MK1 for dirty, noisy, “broken” leads and basses; MK2 for basses with more sub and more singing resonances. If an MK1 bass comes out thin, try MK2 before adding EQ.
• HPF as an instrument: the high-pass with Peak at halfway and cutoff between 200 and 600 Hz gives a nasal lead that sits above the bass without touching it.
• Opposite Link: widens or narrows the band with a single gesture: useful to “open” a sound without changing its center.
• Key tracking: the MS-20 has no dedicated filter key tracking on the panel; patch KBD CV OUT to LP CUTOFF FREQ if the resonance must follow the notes.

Envelopes

• EG2 attack vs decay: in Classic the minimum attack is 24 ms: for percussive clicks switch to Modern (1 ms) and use a negative Decay Curve (-6/-10).
• Hold: keeps the sound after release: with tight sequences reduce it to zero or the notes will overlap.
• EG1 Delay on pitch: a pitch sweep that starts after 200–500 ms gives leads that “bend” at the end of the notes.
• Release and tempo: at 130 BPM an eighth note lasts about 230 ms: EG2 release of 100–200 ms for tight riffs.

Frequencies and mix

• The MS-20 resonances have strong peaks between 1 and 4 kHz: in the mix use a dynamic EQ or a light de-esser instead of lowering the whole volume.
• For distorted basses, cut below 30–40 Hz (useless energy) and keep the character between 80 and 250 Hz.
• VCO 1 noise with high HPF and short decay gives hi-hats; with closed LPF and resonance, snares and toms.

Patching and modulation

• S&H with noise in IN and MG pulse in CLOCK on the cutoff: the classic “thinking computer”; sync the MG to the tempo to make it groove.
• EG1 → pitch with a high amount and attack 0 + short release = synthetic kick.
• VCO 2 ring mod with Pitch near zero: slow, in-tune beating; far from zero: dirty bells.

Velocity, glide, unison

• Moderate Cutoff Mod Sidechain (20–40%) makes basses and leads dynamic.
• Portamento 40–120 ms in Mono Legato for acid slides; with the sequencer use per-step portamento.
• Unison with MK1 is very heavy: for unison leads use MK2.

Common mistakes

• VCO 1 PW at 0%: silence.
• Patches that break internal connections: a cable in an input can disconnect the hard-wired modulation.
• Peak at maximum on both filters with high levels: whistling and volume that explodes.

Presets to recreate

In genres and records

• Techno, acid and 1990s electronic music: documented users include Aphex Twin, Hardfloor, Luke Vibert, The Prodigy, Apollo 440, Coldcut, The Shamen, Biosphere, Astral Projection and Mr. Oizo. Acid basses, sequences, screaming filters.
• EBM and industrial: Front 242, Front Line Assembly, Skinny Puppy, KMFDM, Die Krupps, Severed Heads, Einstürzende Neubauten. Distorted basses and noises.
• Synthpop, electro and electroclash: Vince Clarke, Orchestral Manoeuvres in the Dark, Ladytron, The Faint, Soulwax, Röyksopp, Daft Punk. Dirty leads and basses.
• Electronic music and trip hop: Jean-Michel Jarre, William Orbit, Air, Portishead, Stereolab, Add N to (X), Jimi Tenor.
• Modern rap, trap and drill: distorted leads, glide, ring mod.
• Hyperpop, indie electronic and alt-rock: aggressive leads, sound design.
• Dubstep, bass music, IDM: S&H modulation, extreme resonances, sync.
• Horror and sci-fi soundtracks: sirens, drones, noises.
• Experimental ambient and noise: patches with feedback and external signal processor.