I got a custom A-138c with hand picked resistors. Excellent service
by Doepfer!

Best regards
Jari Jokinen

--- In Doepfer_a100@yahoogroups.com , <hardware@...> wrote:
>
> > The amplification range of my A-138c is not -1 to +1, but
something
> > like -0.9 to +0.9. According to the manual, the range can be
changed by
> > replacing a resistor. I wonder, if it would be difficult to get
very
> > accurately -1 to +1
> >
> > I am routing keyboard CV through the A-138c and precision is
needed. As
> > it is now, I need to add (and tweak) an extra amplification
module to
> > compensate.
> >
> > Does anyone know, how accurate the Serge 3p is
> > http://www.analoguehaven.com/bananalogue/3p/
> >
> > Best regards
> > Jari Jokinen
>
> From the theory the amplification should be +/-1 as all resistors
in the
> circuit are 100k. Probably the actual amplification differs from +/-
1 due to
> the tolerances of the resistors. Another reason maybe the 1k output
> protection resistor (R16). You could short this resistor to try if
it helps.
> It is located just behind the output control.
>
> To obtain exactly +/-1.0 amplification all 100k resistors of the
module have
> to be selected. We can arrange that but additional charges for the
manual
> selection of the resistors (each resistor has to be measured before
> assembly) and the manual assembly/soldering arise.
>
> Best wishes
> Dieter Doepfer
>