[sdiy] AR, AD envelopes

[Tim Parkhurst]

Hi All,

Okay, this should be a stupid simple question, but I want to make sure I've
got it correct in my mind. The more I thought about it, the more I realized
I wasn't 100% sure. Basically, I'm trying to straighten out the differences
between AR and AD envelope generators. Here's what I've got...

AR Envelope: Attack cycle begins when gate signal goes high. If the gate
signal goes low before the Attack cycle has completed, the envelope will
immediately jump to the Release cycle. If gate is still high when Attack
cycle is complete, envelope remains at peak level until the gate goes low,
at which time the Release cycle begins. 

AD Envelope: Attack cycle begins when gate signal goes high. The attack
cycle completes and then the envelope goes to the Decay portion regardless
of the status of the gate signal.

Is this correct? Is there a need for an AD/S (Attack, Decay with Sustain)
envelope? In this one, the attack cycle would complete, the envelope would
remain at peak level as long as the gate signal was high, and then go to the
Decay cycle as soon as the gate went low (this is a little different from
the AR envelope in that the Attack cycle would always finish, even if the
gate goes low before the Attack is complete). 

Again, this should be butt-simple stuff, but I just wanted to make sure. I'm
laying out a simple little EG, and I was curious as to whether the extra AD
and AD/S modes would be worth it. I await your comments, wisdom and insults.


Tim (sweating the details) Servo

"Imagination is more important than knowledge." - Albert Einstein





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