Doepfer

Hello to everyone at Doepfer’s,

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 module’s 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 module’s IC with an ST HCF4052BE and removing the two added resistors?

Hello

The difference between the two brands of the 4052 shouldn't matter.

In regards of the resistors, one would have to know which ones are the 
added resistors and also one would have to know the values of the 
resistors (the regular ones on this module and the added ones).

Florian

Am 03.07.2014 14:18, schrieb thomas_escure@yahoo.fr [Doepfer_a100]:

>
>
> Hello to everyone at Doepfer’s,
>
> 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
> module’s 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 module’s IC
> with an ST HCF4052BE and removing the two added resistors?
>
>
>
>
>

Hello

 > By the way : I call these two resistors "added resistors" because
> obviously they were not part of the initial electronic design of the
> module, since they are soldered to the soldering side of the board, as
> opposed to the component side. And this is a brand new module, it was
> not modified by anyone. Obviously the two resistors have been put there
> at the factory.
I think, that Dieter has to jump in after his vacation, because he is 
the only one who can say whether there were changes in the production run.

Florian

> Hello to everyone at Doepfer’s,
>
> 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 module’s 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 module’s 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