Attack dependant decay/sustain

[Haible Juergen]

	>I just had an idea and I would like to know if sombody else has
thought
	>about this...
	>The idea is to do an attack dependant decay/sustain. Normally, in
acoustic
	>instruments, decay happens with fast attacks due to the inertia of
the
	>interpreter or the instrument itself. But if the interpreter forces
a slow
	>attack (imagine a flute or a violin) there is no decay before the
sustain
	>phase. Based on this, wouldn't it be nice to modulate decay time
and or
	>sustain level depending on attack time? 
	>Has any manufacturer implemented this?
	>It would be easy in a digital design but in an analog one?
	>Just thoughts... 

I can't say too much yet, but apparently the Moog Taurus does some
weird things with its filter envelope. The Gate is AC coupled to the
Attack / Decay stage and it's all very nonlinear, i.e. there are diode
and transitor BE drop voltages that to some truncating of signals -
and the modulation depth is set *before* the Attack / Decay circuit,
not afterwards (as it normally would be).
Some preliminary calculation results: The ENV amount, and the ENV
shape(!) are dependend on the GATE signal, when the gate was last triggered,
if there was intermittent triggering and so on. And the ENV amount
is also changed with Attack time.
All in all this Envelope is more like a "nonlinear BPF" (if you refer to
an ordinary ENV as "nonlinear LPF").

More when I know more ...

JH.