Filter Envelope - Dave Smith Instruments Sequential PROPHET X User Manual

Filter Envelope

The Prophet X filter has a dedicated, 5-stage envelope generator (ADSR
plus delay). The Filter Envelope is used to shape the harmonic charac-
teristics of a synthesized sound by giving you filtering control over its
attack, decay, sustain, and release stages.
This is one of the most important aspects of 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 not how real-world
instruments behave.
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
delay
time
note on note off
A typical 5-stage DADSR envelope
Prophet X User's Guide Filter Envelope 37