Doepfer

> 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