--- In Doepfer_a100@y..., Florian Anwander <
Florian.Anwander@c...> wrote:

> Hi Tim
>
> There is a modification that gives a much better highpass

behaviour at low

> cutoff frequencies to the A-121. I don't know whether it is

documented in

> the service manual. But this may cause a uncontrolled and

unwanted self

> oscillation in high cutoff frequencies.
>
> > I don't have an A-123 high pass module, but I
> > note that it uses the same CEM 3320 chip - it would be

interesting to

> > hear from other list members whether it behaves in a similar

fashion.

> No. As far I understood the problem appears only in the state-

variable

> circuit. And the 123 is a pute pure hipass filter.
>
> Florian

That was going to be my next question, whether the A-123 has
the same characteristics.

I'd be interested to know more about that modification to the A-
121 though.

Thanks to all for the extensive information.

M. Dimm.