KORG MS-20 - The Iconic Analog Synthesizer That Stands the Test of Time

Korg MS-20 is one of the most renowned analog synthesizers, becoming a legend thanks to its semi-modular architecture, aggressive filters, and flexible sound design options. This instrument was introduced in 1978 and remained in production until 1983. Due to its unique construction and wide range of connectivity options, it became popular among experimental musicians, producers, and sound designers.

History and Development of Korg MS-20

The MS-20 was designed as an affordable semi-modular synthesizer, allowing users to connect different modules using patch cables. Unlike fully modular systems, the MS-20 had a fixed internal signal path, which could be rerouted via its patch panel. This concept enabled users to experiment with sound without requiring complex programming.

During its production, the MS-20 underwent two main versions, differing in their filter types:

Older version featured the Korg 35 filter, known for its aggressive resonance and distinct “screaming” character. Newer version was equipped with the LM13600 filter, which had a smoother response and less aggressive resonance.

Technological Innovations – What Makes MS-20 Special?

The MS-20 introduced several key innovations that set it apart from other synthesizers:

•  Two independent VCOs – each oscillator had its own tuning, waveform, and modulation controls.
•  Dual filters in series – combining high-pass and low-pass filters allowed complex frequency shaping.
•  External Signal Processor (ESP) – enabled control of the synthesizer using external audio sources.
•  Patch panel – provided extensive connectivity options for experimental sound design.
•  Two envelope generators – allowed detailed control over sound dynamics.

Oscillators and Sound Architecture

The MS-20 used two VCOs, offering various waveforms:

•  VCO1: Triangle, sawtooth, pulse wave, white noise.
•  VCO2: Sawtooth, square, narrow pulse, ring modulation.

Through frequency modulation, users could create complex sound textures, ranging from deep basses to experimental noise effects.

Filters and Modulation

One of the most distinctive features of the MS-20 was its dual self-oscillating filter setup with distinctive distortion, arranged in series:

•  High-pass filter – helped remove low frequencies and create sharp tones.
•  Low-pass filter – delivered warm analog character to the sound.

Filters could be modulated via LFO, envelope, or external signals, allowing dynamic frequency shifts.

Effects and External Signal Processor

The MS-20 featured an External Signal Processor (ESP), enabling:

•  Control of oscillators via external sounds (e.g., a microphone or guitar).
•  Frequency-to-voltage conversion – allowed pitch tracking from external audio signals.
•  Envelope follower – modulated parameters based on the volume of an external signal.

Connectivity and Studio Integration

The MS-20 was equipped with CV/Gate inputs and outputs, facilitating integration with modular systems. Additionally, it offered:

•  VCF mod input – allowed external modulation of the filter.
•  VCO mod input – enabled connections with additional oscillators or external LFOs.
•  Patch panel – permitted custom signal routing, making experimental sound shaping possible.

Unconventional Signal Routing on Korg MS-20

One of the greatest strengths of the MS-20 is its semi-modular architecture, which allows non-standard routing via its patch panel. This capability helps create unique sound structures not typically found in standard analog synthesizers.

Unique Signal Routing Techniques

•  Self-oscillating filter as an oscillator – the MS-20’s resonant filter can be adjusted to
   produce a pure sine wave, effectively serving as an additional oscillator.
•  Envelope feedback loops – by routing the envelope’s output back into VCF or VCA, users
   can create dynamic tonal shifts.
•  FM between oscillators – connecting VCO1 to VCO2’s frequency input creates complex
   frequency modulation, adding a metallic character to the sound.
•  External signal modulation – using ESP (External Signal Processor), users can apply external
   sounds to modulate MS-20’s parameters, such as controlling the filter with a voice or guitar.

These techniques enable experimental sound design, ideal for film music, ambient compositions, and avant-garde electronic production.

DIY Mods and Customizations for Korg MS-20

The MS-20 is popular among musicians who enjoy customizing their instruments. Several well-known DIY modifications extend its capabilities.

Popular Hardware Mods

•  MIDI expansion – adding MIDI input/output enables direct integration with DAWs and
   external sequencers.
•  Improved tuning stability – modifications can add temperature-compensated oscillators, improving
   pitch stability.
•  Expanded patch panel – adding additional inputs/outputs enhances advanced modular connections.
•  Exponential FM – some modifications allow deeper frequency modulation, producing richer
   harmonic textures.

Software Modifications and Emulations

•  Virtual MS-20 – software versions of the MS-20 provide accurate digital emulations of its
   analog sound.
•  Hybrid modular integration – some musicians connect the MS-20 to Eurorack modules, expanding
   its modulation options.

Thanks to these upgrades, the MS-20 remains one of the most adaptable synthesizers, seamlessly integrating into modern studio setups.

Comparison with Other Synthesizers of Its Era

The MS-20 was launched during a time when analog synthesizers were booming. How did it compare to competitors?

Korg MS-20 vs. ARP 2600

Although the concept of these instruments is quite similar, the ARP 2600 was real professional three-oscillator semi-modular synthesizer, whereas the MS-20 was semi-modular instrument at a quarter of the price but with unique frequency low-pass and high-pass filters.

Korg MS-20 vs. Moog Minimoog

Minimoog had a warmer tone with more standard, albeit completely iconic sound potential, while the MS-20 was patchable semi-modular synth featured aggressive filters suited for experimental sound design.

Korg MS-20 vs. Roland SH-101

SH-101 was simpler but included arpegiator and sequencer, while the MS-20 offered extensive modulation capabilities and also high-pass filter.

Modern Reissues and Current MS-20 Versions

Due to the long-standing popularity of vintage MS-20 synthesizers, Korg released a reissue series in 2013, called the MS-20 Mini (the classic MS-20 – recreated in mini size). Compared to the original, the MS-20 Mini featured USB and DIN-style MIDI connectors for easy connectivity during studio work. In 2014, the Korg company also introduced MS-20 Module (a desktop version), with expanding modulation possibilities, for example, oscillator synchronization, FM, and also the ability to switch between individual emulations of frequency filter types (REV 1 – Korg 35 and REV 2 – LM13600) directly on the instrument on-board.

In 2020, Korg released a limited re-edition (between musicians very asked full-size version),  the Korg MS-20 FS, which unlike the desktop version, did not offer oscillator synchronization and FM modulation. Also, switching between the REV 1 and REV 2 frequency filter emulations was only possible using a switch located inside the instrument. Unfortunately, despite the continued interest of musicians, the Korg company now only offers the smaller version, Korg MS-20 Mini.

Cultural Impact of Korg MS-20

The MS-20 became a favorite instrument among musicians, its distinctive sound appearing in the works of artists such as:

•  Aphex Twin
•  Daft Punk
•  Portishead
•  Mr. Oizo
•  The Prodigy

Conclusion

The Korg MS-20 is a timeless analog synthesizer, defining a new approach to semi-modular synthesis. With its aggressive filters, flexible modulation, which allows to create unique sound effects, it has become an icon of electronic music. Even today, it remains a source of inspiration for musicians and producers.