> Thanks Ingo especially for the tip regarding the A170.
> Do I need 2 of the xtreme filter I thought that the module contains
> a LP and HP in one

i'm afraid that you really need two xtreme filters to replicate
the filter section of the ms20. the ms20 has independent filters
for lowpass and highpass, which means that they can have different
cutoff frequency and different resonance, so you will get two
different resonant peaks in the spectrum at the same time and
you can form a bandpass with variable width. all this is not
possible with only one xtreme filter.
also there is the sy02 filter available from analogue solutions,
which is a module with independent filters for high- and lowpass
and a final vca. it is not as versatile as two a106/1, but
it still is a good deal, especially when thinking about the
low british pound. in my opinion two a106/1 sound better than
one sy02, but that is a matter of taste.

> Is there a way to shift/to offset a voltage in positive range or
> negative range only I'm thinking to have (i.e. LFO/ADSR) a
> positive range (no inversion).

there are several ways to shift a bipolar voltage
(f.e. from an lfo) into positive or negative range only.
you could do that with an a138c polarizing mixer (which also has
an offset function on the first channel) or the new a183-2
offset/polarizer module.

best wishes

ingo