Hi Ernst,

> It seems that my two a-131's are differently calibrated in their
> response to CV. Does
> anyone else here have this problem too

I have only one A-131, so I cannot speak from experience (and it is
also the newer version, marked 'v2 2001') but this doesn't surprise
me. Because of the exponential response, at higher levels of CV
input, a small change of CV produces a large change of gain, and it
is unlikely that the factory set-up procedure is precise enough that
all A-131s have exactly the same response.

The response curve is controlled by two trimpots in the circuit, and
also probably by how well transistors Q1 and Q2 are matched. It may
be possible to adjust the trimpots on your modules to get them to
match more closely, but it would require a good DVM, and a lot of
patience, as the two adjustments will interact to a certain degree
(and knowing what the factory set-up procedure is, presumably in the
technical manual, would also be an advantage!).

Tim