Ugh - the complicated quad EG emulation v1 is seriously bugged.
The 4th EG was completely broken, and the retrigger blocking logic did not work properly if the gate is held high while the sustain is off.
A corrected version 2 required significant changes. The logic module was replaced by 4 T type flip flops. In order for looping to work I had to set the Envelope Factories to use fast triggers (1 sample instead of 1 msec). But this then required a 2nd AD/ASR per EG to convert the EOC 1 sample triggers back into 1 msec triggers.
Here is the corrected version 2.
Buchla 284 Quad VC Envelope Generator v2.vcv (10.3 KB)
And here is an image of the functional internals for v2. The UI has not changed.
All in all, I think the single Envelope Factory per envelope generator is a much better solution.