Shapers
Low-Pass Gate
A low-pass gate: a filter and a VCA that close together. The secret behind “west coast” plucky, wooden, bongo-like notes.
Learn about it in Envelopes & VCAs: how notes start and stop
How it works
A STRIKE opens it fully, and then it closes the way an old vactrol does: quickly at first, then with a long soft tail. Because the filter closes with the volume, notes get darker as they fade — like a real struck object. CV holds it open instead (an LFO, an envelope, a voltage). BOTH is the classic sound; FILTER keeps only the tone change, VCA only the volume change.
Inputs
| IN | Audio to gate — a VCO, noise, a resonator. |
|---|---|
| STRIKE | A trigger plays a note. |
| CV | Opens it by this much (0–1) without a strike. |
Outputs
| OUT | The gated sound. |
|---|
Knobs and switches
| BOTH / FILTER / VCA | Filter and VCA, filter only, or VCA only. |
|---|---|
| Decay | How long notes take to close. |
| Res | Filter resonance — a woody “bonk” when high. |
Patches to try
- A sine or triangle VCO in, Euclid into STRIKE: instant marimba.
- Noise in, short decay: shakers and brushes.
Lessons that use the Low-Pass Gate
Each one opens as a working patch in the synth.
Words to know
- Filter — Removes part of the frequency range, making a sound darker, thinner or more focused.