Alesis micron Reference Manual

 

For each of the three envelopes, set the attack time and slope 
(Atk), the decay time and slope (Dcy), the sustain time and level 
(Sust), and the release time and slope (Rel). 
 
The sustain time parameter determines the length of the sustain 
stage of the envelope.  If you are familiar with analog synths, this 
parameter may surprise you, since a traditional synth will remain in 
the sustain stage as long as you have the note held down.  The 
Micron provides this behavior, of course–simply set this parameter 
to “hold”, and your note will be sustained until your finger gets 
tired.  But many physical instruments do not work like this.  A 
piano, for example, exhibits a distinct attack and decay as the 
hammer strikes the string, but the string does not then ring 
forever—the volume slowly diminishes until the string is silent.  
The Micron allows you to model this behavior by specifying a 
sustain time.  This is the amount of time it takes for the envelope 
level to drop from the sustain level to zero.  Once the envelope 
has sustained to zero, the envelope has completed and will remain 
at zero.  When the amp envelope has sustained to zero, that means 
the entire note has completed and will no longer use one of the 
synth’s voices.   
 
The sustain level parameter specifies the level that the sound settles 
into as the envelope completes its decay and moves into the 
sustain stage.  At 100%, decay becomes inaudible.  At 0%, the 
decay becomes complete, resulting in silence.  Generally, values in 
the middle of the range are most useful.    
 
For the filter and pitch/mod envelopes, this parameter can be 
negative.  Since the subsequent envelope stages always head back 
towards zero, a negative sustain level will give you an envelope 
that zigs high, zags low, and ends up somewhere in the middle. 
 
Here are the additional envelope parameters: