This adjustable envelop can have note off occur at any time and fade out from there. I tested it a bit to make sure there wasn't an odd state where this would happen but of course I could still be missing something.
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What is the processor usage of the TSynth usually?
I can't replicate the click. Is it happening in other modes? Is it the resonance of the filter clipping?
I finally fixed up my adjustable envelope object I've been messing around with forever. You can get it here.
Shape is adjustabe from a sharp exponential curve, 1.0 is a very chonky log for each ADSR stage....