AW: [Doepfer_a100] Envelope Generator Problem

From yahoo
Sent Tue, Nov 7th 2017, 15:26

Hello,

I took an A-140 and cannot confirm this behaviour. That's what I did:

- wait about 10 seconds
- permanent high signal to the gate input
- measuring the ADSR output (especially the peak voltage) with
oscilloscope -> peak is about +8.4V
- replacing the permanent gate signal by an LFO rectangle with about 10 Hz
- measuring the ADSR output (especially the peak voltages) with
oscilloscope -> all peaks are about +8.4V

I could detect any difference in the peak level of the "first" envelope
(permanent gate) and the peak levels when the A-140 was triggered by the
LFO.

Best wishes
Dieter Doepfer



> -----Ursprüngliche Nachricht-----
> Von: xxxxxxx_xxxx@xxxxxxxxxxx.xxx [mailto:xxxxxxx_xxxx@xxxxxxxxxxx.xxx]
> Gesendet: Dienstag, 7. November 2017 04:11
> An: xxxxxxx_xxxx@xxxxxxxxxxx.xxx
> Betreff: [Doepfer_a100] Envelope Generator Problem
>
>
>
>
>
> 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
>
>
>
>
>
> 



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