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9 - Synthesizer Basics
Envelope Generators
Envelope Generators
An envelope can be described as a "contour" which can be used to shape the sound in
some way over time. There are three envelope generators per voice and all of them are
the rate/level type.
This is how the rate/level envelopes work: When a key is pressed, envelope starts from
zero and moves toward the Attack 1 Level at the Attack 1 Rate. As soon as it reaches this
first stage, it immediately begins the Attack 2 phase and moves toward the Attack 2 level
at the Attack 2 rate. As long as the key is still held, the envelope continues on through
the Decay 1 and Decay 2 stages. If the key is still held when the envelope reaches the end
of Decay 2, it simply stops there waiting for you to release the key. When you release the
key, the envelope continues through its Release 1 and Release 2 stages, stopping at the
end of the Release 2 stage. The rate/level envelopes give maximum flexibility to program
both complex and simple envelopes.
level
time
Key
Down
The Amplifier Envelope generator controls the volume of the voice over time and has 6
stages: Attack 1, Attack 2, Decay 1, Decay 2, Release 1 and Release 2. The Filter Envelope
generator controls the filter morph and also has 6 stages. Unlike the amplifier envelope,
however, the filter envelope has the ability to go negative as well as positive. There is
also an Auxiliary Envelope generator which is a general purpose envelope. The auxiliary
envelope is identical to the filter envelope and can go negative as well as positive. The
time of each stage can be adjusted to create myriad envelope shapes, which in turn
shape the sound over time.
The way the volume of a sound changes over time determines how we perceive that
sound. For example, a bell struck with a hammer is instantly at full volume, then slowly
dies away. A bowed violin sound fades in more slowly and dies away slowly. Using the
Amplifier Envelope, you can simulate different types of instrument volume envelopes by
programming them appropriately.
Retriggering
The Filter and Auxiliary envelopes can be retriggered by an LFO or any other
modulation source such as clock divisor.
Patch the desired modulation source (using a positive value) to Filter Env Trigger or Aux
Env Trigger. Envelopes are triggered on a positive-going edge.
146
until key release
Sustain
Key
Released
(See "Clock Modulation" on page 148.)
f
generators are just like
standard ADSR' s , except
that they have two
segments for each stage.
To create a standard
ADSR curve, set the
"2" levels the same as the
"1" levels and set all the
"2" rates to 0.
Holds here
f
Auxiliary Envelope to
control the pitch (Cords)
you can easily hear the
shape of the envelopes
you are creating.
Proteus X Operation Manual
The EOS envelope
By routing the
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