Polysynth chips, MS-20 and Steiner
Three filter chips gave the great polysynths of the late 1970s and early 80s their voices. Two more circuits gave monosynths their scream and their bite. KiMiA has all five, modeled on what is published about them.
- Hear the three polysynth chips side by side
- Make the MS-20 scream and the Steiner bite
- Choose a circuit for a pad, a brass section or a lead
01Three polysynth chips
When polyphonic synthesizers arrived, every voice needed its own filter, and that meant chips. Three of them shaped the sound of a whole era. KiMiA names its three types after them: IR3109, SSM2040 and CEM3320.
All three are four stages in a loop, as the Poly is (Lesson 6.1), and all three take Slope: 12 or 24 dB. They differ in where their circuits clip and in how much bass their resonance takes away, which is exactly what you hear in a chord:
Three polysynth chips at the same setting
| Type | Where it comes from | Its character | Reach for it when |
|---|---|---|---|
| IR3109 | The great Japanese polysynths and their smaller siblings | Each stage saturates on its own; it keeps its level as resonance rises | Brass, strings, lush pads |
| SSM2040 | The first American five-voice polysynth, early models | Warm and fat; its resonance is softer and compressed; the least bass lost | Big, round pads and poly basses |
| CEM3320 | The later American polysynths | The cleanest; it clips only in its resonance path; the most bass lost | Bright, defined chords that cut through |
Choosing between the chips is a matter of seconds: load a pad, hold a chord, click the three types in turn. The differences are small on a chart and clear in a band. When in doubt, SSM2040 for warmth, CEM3320 for clarity.
02MS-20: the scream
The MS-20 LP and MS-20 HP types follow the filters of a famous late-1970s Japanese semi-modular monosynth. The low-pass is 12 dB, and its resonance runs through a clipper: the harder you push it, the more it screams, but it never blows up. The high-pass is gentler and has a peak of its own.
The MS-20 filters: low-pass and high-pass
That clipper is the point. On most filters, very high resonance whistles; on the MS-20 it snarls, and a driven MS-20 lead cuts through any mix. At the very top of Resonance it sings a steady sine of its own, as the Ladder does.
Load 06 · MS-20 Scream and play a bluesy lead. Push the mod wheel… nothing yet: Module 14 shows how to put the Cutoff on your wheel. For now, ride Cutoff and Resonance with your free hand while you play.
03Steiner: the bite
The Steiner type follows a rare American filter of the 1970s, made famous again by later analog monosynths. One core gives low-pass, band-pass and high-pass at once, and a Mode knob, in the Slope row’s place, sweeps between them. Its diodes clip the resonance hard.
The Steiner-Parker: one core, three outputs
Clean, the Steiner is an ordinary, slightly hollow filter. Driven and resonant, it bites: the clipping turns the peak into a gritty edge, ideal for basses and aggressive leads. Mode a little toward band-pass thins the low end and adds a nasal bark.
04Which circuit for which sound
| Sound | First choice | Why |
|---|---|---|
| Poly brass, strings | IR3109 | Keeps its level as you push the resonance |
| Warm pad under a singer | SSM2040 or Poly | Fat and soft, compresses big chords |
| Bright, defined chords | CEM3320 | Clean, lean low end |
| Screaming lead | MS-20 LP with Drive | Resonance that snarls instead of whistling |
| Biting bass | Steiner, Mode toward band-pass, Drive | Hard-clipping resonance |
| Classic mono bass and lead | Ladder (Lesson 6.1) | Warm, thick, singing |
05Try it
- Compare the chips. Load 06 · Chip Brass and play a few chords, soft and hard. Switch the Type between IR3109, SSM2040 and CEM3320. Which one would you use in a ballad, and which in a funk tune?
- Make it scream. Load 06 · MS-20 Scream. Raise Drive to 70% and Resonance toward the top while you play. Then try the same on the Ladder: hear the difference?
- Find the bite. Load 06 · Steiner Bite and play the bass line of your favorite funk tune. Move Mode from 0 to 50% while you play.
- The MS-20 band. Load 06 · Course Init. Set Filter 1 to MS-20 HP at 300 Hz and Filter 2 to MS-20 LP at 2 kHz, Routing 1 → 2, both Resonance 60%. Play a lead and sweep both cutoffs.