Emulator Composite.book - Creative

12 - 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.
time
level
Atk1
Key
Down
Atk2
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. (See “Clock Modulation” on page 282.)
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.
Dcy1
Dcy2
Sustain
Complete Mode
In Complete mode, the envelope generator continues through all six stages when a key
is pressed, ignoring the status of key sustain. This feature allows you to create long
evolving soundscapes with a quick tap of the key, enveloping percussive sounds such
as piano and drums, or plucked strings. This mode is also useful to conserve CPU
resources, since the voice will turn off as soon as the amp envelope cycle completes.
The EOS envelope
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.
By routing the
Auxiliary Envelope to
control the pitch (Cords)
you can easily hear the
shape of the envelopes
you are creating.
280 Emulator X2 Operation Manual
Rls1
Key
Released
Holds here
until key release
Rls2