From yahoo Sent Mon, Jul 7th 2014, 09:41
From yahoo Sent Mon, Jul 7th 2014, 09:41
> Hello to everyone at Doepfers,
>
> I have a two-voice system in which I use two A-141-1 modules as
> amplitude envelope generators to drive the final VCAs (second
> generation A-131s).
>
> Some time ago I discovered that the envelope curves seem to be a
> little different from one A-141-1 to the other. When connected to
> the same A-131, it appears that one of the two A-141-1 is
> definitely a little sluggish compared to the other one.
>
> I was curious to see if there could be differences in their
> circuits and/or if I could find trimmers to adjust the curves, so
> I took the A-141-1 modules out of the rack and had a look at the boards.
> There I noticed that the IC at the upper right of each main board
> was not the same for the two modules. The first module has an ST
> HCF4052BE while the second one has a TI CD4052BE.
> Also there are two added resistors on the soldering side of the
> second modules main board.
>
> Could these differences be the reason why the two modules have a
> slightly different behaviour? And if so, do you think that I
> could get the same curves from the two modules by changing the
> second modules IC with an ST HCF4052BE and removing the two
> added resistors?
I'm back from holidays and are able to answer questions again.
There is a trimming potentiometer labelled P9 OFFSET on the pcb. I suppose
that the setting of this parameter is a bit different for the two modules.
I'd use one of the modules as reference and adjust P9 of the other module so
that they behave in the same way. You may e.g. set the attack control for
both to 3 and trigger both modules with the same gate signal. Then adjust P9
of the second module so that the attack time is nearly the same as for
module #1.
Best wishes
Dieter Doepfer
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