22 Filter Envelope
Dave Smith Instruments
Filter Envelope
The Prophet-6’s low-pass and high-pass filters share a dedicated, four-
stage envelope generator. The Filter Envelope is used to shape the
harmonic characteristics of a synthesized sound by giving you filtering
control over its attack, decay, sustain, and release stages.
This is one of the most important factors in designing a sound. Without
an envelope, the filters would be completely static. They would stay
open or closed by a fixed amount that wouldn’t change over the duration
of a sound. That’s not very interesting to listen to and it’s not how instru-
ments behave in the real world.
In general, sounds produced by an instrument are brighter at their begin-
ning (the attack stage) and grow mellower as they die out (the decay
and release stages). In other words, their harmonic content changes over
time. This is exactly what the filter envelope is designed to emulate.
FILTER ENVELOPE
ATTACK
DECAY
SUSTAIN
RELEASE
Filter envelope
Attack
Decay
Sustain
Release
Amplitude
Time
A typical 4-stage envelope