22 Filter Envelope
Sequential
Setting
keyboard
to
full
when the filter is self oscillating will cause the filter-
generated pitch to follow the keyboard in tune (i.e. in semitones). Setting the
keyboard
to
half
will cause the filter-generated pitch to follow the keyboard pitch in quarter
tones.
Filter Envelope
The Trigon-6’s lowpass filter is modulated by a dedicated four-stage
envelope generator. The Filter Envelope is used to shape the harmonic
characteristics of a synthesized sound over time 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 instruments
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