hello joachim,

> I would like to share two module suggestion that came to my mind
> while patching:
>
> 1. A simple and cheap dual 48 db filter to use with the BBD modules.
> Only 2 jacks (in/out) and 1 potentiometer (frequency) per filter.

in principle a good idea, but i'm not sure if it would be
really satisfying for using it with a bbd, at least for me.
without a cv input the filter cannot follow the clock of the bbd,
which means that you need to close the filter more than necessary,
when the delay time is modulated. the a188 has a cv output for
controlling a vcf, so you can dial in just as much filtering as
necessary, which is a great feature imho. this is of course not
valid if the delay time is not modulated, but isn't that a big
part of the fun on bbd delays often i also add a slight portion
of resonance on the vcf to emphasize the higher frequencies,
which reduces the dulling effect even more. i always use
the a108 for that, but somehow it is a bit of an overkill,
especially when you want to filter before and after the bbd
and therefore need two of them. so to make it cheaper without
omiting the useful things, i would prefer a very steep
dual vcf with reduced functions. only one cv input per channel
instead of 3, no resonance insert, no attenuators for the
audio input and a more neutral sounding and simpler filter
circuit (no need for selected transistor ladder stuff here).
it should have 48db steepness, or even 60db if possible.
i want such a module since the a188 is available and i would
buy it instantly. there was a switched capacitor dual filter in
the planning stage some years ago, for exactly this purpose,
but i believe that technical issues delayed the development
and i don't know if this project is still alive.

> 2. A simple and cheap (maybe passive) Hipass filter (80 Hz), maybe also
> dual:
> 2 jacks (in/out) + bypass switch.
> Useful for modules which generate too much low end signals.
> If it would be active and dual, one 80 Hz and one 40 Hz filter would
> make sense in my eyes. The latter could then be used for basses and
> bassdrums and cut those frequencies that almost no loudspeaker can
> handle and thus increase the headroom and help reduce some nasty
> unwanted distortion effects.

a passive dual highpass filter is not a bad idea,
i just don't know how many people would buy it,
as it is a very simple circuit.
maybe you should start a poll

best wishes

ingo