Envelope Follower

Extracts the amplitude envelope of an audio signal and emits it as control voltage. Patch the output anywhere you'd normally use an envelope or LFO, and your modulation now breathes with the dynamics of the sound that's driving it.

How it works

The module rectifies the incoming audio and tracks its level with a one-pole follower that uses separate rise and fall times: when the signal gets louder the Attack time governs how fast the envelope climbs, and when it falls away Release controls how gently it decays. A quick attack and slow release gives the classic smooth, trailing contour. Output is 0–10V CV scaled so a full-level signal reaches near the top of the range.

Controls

  • Attack — how quickly the envelope rises toward a louder input. Sweeps from roughly 1 ms (snaps to every transient) up to 1 s (smooths past them).
  • Release — how slowly the envelope falls when the input quietens; same 1 ms–1 s range. Longer release smears percussive sources into a flowing contour.
  • Gain — boosts or trims the input before tracking; turn it up to follow quiet signals, or back to keep loud ones off the ceiling.

Inputs & outputs

  • In — the audio you want to track. Drums, a vocal, a full mix — anything with movement.
  • Env — the extracted envelope as 0–10V CV.

Tips

  • Feed Env to a filter cutoff or VCA and side-chain one sound to the dynamics of another — a kick can duck a pad, or a hi-hat can shimmer a reverb.
  • Short Attack with long Release is the sweet spot for turning a busy rhythm into smooth, musical modulation.