[Fpga-synth] Linear / Expo Release for ADSR Working

[Eric Brombaugh]

Scott Gravenhorst wrote:
> I've got my ADSR modified to release linearly or exponentially on a
> selectable basis.  I like it.  I'm getting some pretty good bell sounds now
> with GateManPoly/8.  

You beat me to it! I spent yesterday diddling with a delay line, but 
I've got a start on my expo release & hope to have it going some evening 
this week. I need to build a simple ASR for the FM index parameter too - 
it sounds good running from the mod wheel, but consistent variations 
would be nice to have also.

Eric