Doepfer

--- In Doepfer_a100@yahoogroups.com, <hardware@...> wrote:
>
> 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
> >


hi Dieter

Is there a PDF available for the service manual for the A-131 to help me identify the 
correct resistors?

vielen dank
sean