Doepfer

Sorry, I overlooked that Sean was asking for the old version of the A-131:

Increasing the input level: increase R10 (now 47k)
Increasing the output level: increase R12 (now 47k)

Best wishes
Dieter Doepfer


> -----Ursprüngliche Nachricht-----
> Von: Doepfer_a100@yahoogroups.com
> [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von Florian Anwander
> Gesendet: Montag, 21. August 2006 14:14
> An: Doepfer_a100@yahoogroups.com
> Betreff: Re: [Doepfer_a100] A-131 Increased Gain modification
>
>
> hi Sean
>
> > I'm trying to modify my old style A-131 Exp. VCA module to get a
> > gain >1 as the output often seems weedy and I would like the option
> > of a little (or a lot of) overdrive.
> >
> > I'm guessing that I can do this in 2 ways:
> > 1. change the resistors connected to the audio In pots to a lower value.
> > 2. change the resistor connected to the output voltage of the
> CV circuit.
> I think the VCAs OTA is not the place where you should change the level.
> Usually a change of amplification should be done by decreasing the
> feedback resistor of an OpAmp. As far as I remember, the old A131 with
> the Curtis CEM3382 does not use an separate buffer stage at the output
> (thats where you might do this). So I suggest to modify a Mixer A-138,
> where you could change either the feedback of the summing amp (to
> amplify all four inputs), or change the input resistor of one channel.
>
> Florian
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>