The canonical subtractive voice patch routes oscillator → filter → VCA with two envelopes: one for amplitude, one for filter cutoff

The subtractive voice is the foundational Eurorack patch that underlies most synthesizer architectures from the Minimoog to Native Instruments Massive: an oscillator feeds a filter to shape timbre, the filter output feeds a VCA to shape amplitude. Two ADSR envelopes are needed — one controls the VCA (amplitude envelope, shaping the overall dynamic), the other is run through an attenuator and modulates the filter cutoff (filter envelope, adding timbral movement). The attenuator scales how far the filter opens on each note. This architecture generates the classic ‘note with a tone colour that moves’ that distinguishes synthesizers from static tones.

Examples

Patch: Oscillator → Viol Ruina filter in → filter out → VCA audio in → output. ADSR 1 → VCA CV. ADSR 2 → attenuator → filter cutoff CV. Both ADSRs triggered by the same gate. Fast filter envelope + slow amplitude envelope = percussive click fading into a pad.

Assessment

Name the four modules in the canonical subtractive voice patch and describe each one’s role; then explain why the filter envelope needs an attenuator and the amplitude envelope usually does not.