Component
VCA
v0.5.108
Amplifier: controls the volume.
Software v0.5.108
Overview
Amplifier: controls the volume.
A voltage-controlled amplifier. Gain sets a base level and the CV input adds on top: patch an envelope into CV with Gain at 0 and every note gets its shape; turn Gain up and the VCA stays partly open, with the envelope riding on top. With Gain at 0 and nothing on CV the VCA is closed.
Resp chooses the curve. Lin is linear (0.5 gives half the amplitude); Exp is exponential over 48 dB, so an envelope decay sounds like a natural fade rather than a sudden drop at the end.
Controls
| Control | Range | Default | What it does |
|---|---|---|---|
| Gain | 0 … 1 | 0 | The base volume; an envelope on CV adds on top. |
| Resp | Lin / Exp | Lin | Lin: in a straight line. Exp: an exponential curve, so an envelope fades naturally. |
Ports
| Port | Direction | Signal | What it carries |
|---|---|---|---|
| In | in | audio | The audio to be amplified. |
| CV | in | cv | The level, 0 … 1, typically from an envelope; linear. |
| Out | out | audio | The audio at the level set by CV. |
How it works
The level is Gain + CV, limited to 0 … 1, then shaped by the curve. The VCA multiplies the audio by that level. The CV arrives at the control rate (1 kHz); to avoid zipper noise from those 1 ms steps, each new value is reached with a 2 ms linear slide, so the steps join into a smooth curve.
Runs on
- Teensy 4.1 (the MusicBrain Brain): about 0.2 % CPU per instance (one note, default settings), measured on firmware 0.5.108.
- The browser: the editor's simulator runs the same C++ code as WebAssembly, so what you hear while patching is what the Brain plays.
Try it
Patches to play (open them in the editor from their page): 6-stemmig ladder-filter.
In the editor's example set: 1-stemmig (mono), 2-stemmig, 4-stemmig, 8-stemmig, 16-stemmig, 4-stemmig + aftertouch → filter, 🎺 CS-80 brass (aftertouch), 🎹 Axel F-lead (2 saws), Reservoir demo (gedeelde bron), 🌌 Krell (zelfspelend), 🎺 CS-80 brass ×4, 🎸 Axel F lead, 🌌 Krell.
Editor: https://editor.musicbrain.nl
Sources & licences
- The multiplier is
AudioEffectMultiply, with anAudioSynthWaveformDccarrying the level, from the Teensy Audio Library by PJRC (MIT licence). - The MusicBrain module code is MIT licensed.
Versions
- 0.5.108: Gain and Resp work (before, only the CV set the level).
- First version (May 2026): linear VCA with the 2 ms CV slide.