On Tue, 2 Dec 2008 17:59:42 +0000 "Solen Music" solenpuredata@googlemail.com wrote:
Does anybody know if there's any theory about soft knees, program related releases, etc., so as to maybe emulate opto style compression or other types of esoteric compression?
Putting a low pass filter of a few Hz into the side chain can provide an attack. To soften the knee you need a smooth transfer function that multiplies the gain curve (so its a sort of second order thing). Places a curve between the linear 1:1 gain and reduced gain 1:n lines.
Opto is a feed forward style, and IIRC the photoresistor (ORP12 CdS2) has a slight persistence so it responds sluggishly to changes. I'm not sure if that's actually due to the slow cooling of a filament lamp some designs use one, but others use a LED which seems to be instant on/off)
Anyway, you could model feed-forward in Pd using a small delay buffer and a lowpass filter.