Hi Folks

 

Sorry to post this again but my whole modular synth is unusable until I fix this problem so I still need help.

 

The problem: All of my envelope generators do the same thing - When I play a note they peak at a certain voltage, lets say 5 volts. But when I play a second note that peak rises to 6 volts. And in some cases when I play 16th notes it rises even more.

 

So when I connect the output of an envelope generator to a VCA the first note I play is always MUCH quieter than every following note.

 

I have 3 Doepfer LC9 cases with various modules in each. This behavior is consistent in all three boxes with all of my envelope generators.

 

The modules are:

Doepfer A-140 (3 of these)

Doepfer A-143-2 quad

Roland 540

 

Also, the all 4 of the envelopes in the A-143-2 do not actually sustain. The voltage constantly falls when a note is held, even when the sustain level is set to maximum. That is a separate problem but I thought I'd mention it.

 

Also, for some reason the release time of the Roland 540 is only 2 seconds (even on the Slow setting) when plugged into any VCA, however when it is plugged into the Roland filter the release time is much longer. Another weird problem but I thought I'd mention it in case it was an important clue.

 

I have tested the output of all of the envelopes with both analog and digital volt meters to confirm the behavior.

 

At this point I'm not sure what to do to fix this. I guess the first question is:  Is this the way these envelopes are supposed to work   I have owned analog synthesizers since 1978 and own a lot of them right now and not a single one has this behavior. Other than when using velocity sensitivity, every note played is exactly the same volume.

 

Is this a known issue Are there combination of modules that can cause this to happen Could it be the power supplies I have moved the modules around and found the behavior is the same regardless of how many modules (or which ones) are in a case.

 

What kind of troubleshooting can I do With only a trigger voltage being sent to the Envelope module I don't think there could be anything else interfering but I'm looking for any clues at all, even the most obvious ones that I may have overlooked.

 

I did a video to show the problem:  https://youtu.be/x8_1ZnmPWLo

 

Thanks for any ideas anyone might have!

 

Scott