Hi

> the a121
> highpass is somehow strange when putting to low frequencies (more
> like
> bandpass),

This is a known problem of this chip and it is described in the service
manual of the A100:

You have two possibilities with the circuit:
either to have a controllable resonance behaviour for the price of a
littlebit limited hipass characteristics

or to have a perfect hipass characterics but uncontrollable and
unstopable selfoscillation when the cutoff frequencey became once quite
high.


This is not a fault of Doepfers module, but a problem of all
Multimodefilters that use the CEM3320.


Florian


btw:
I only can recommend to buy the service manual. It contains a lot of
explanations and tips!