[sdiy] Re: hot rod 2044, was Re: "Reviving" the CEM3396

[Harry Bissell Jr]

Hi John (et al)

The expander trick is what I was referring to... but
to say the 2040 is a 'multi-mode' is a little
misleading.  It "might: be multi-mode if you
configured it that way, but most uses would be
straight 4 pole.
The data sheet shows other uses like SVF etc.

The 2040 and 2044 would be similar in the Oberheim
filter. Craig Anderton (whose RTL based fuzzbox was my
first diy project :^) also has a "Multiple Identity
Filter" design using the same technique.

The 3396 was correctly identified as not being useful
for this (because the filter output goes right to the
VCA internally.

H^) harry


--- john mahoney <jmahoney at gate.net> wrote:

> Harry,
> This 3372 trick (thanks, Rainer!) sounds like what
> you were suggesting
> for the SSM2044, which is also a 4-pole VCF chip
> (not a multi-mode
> filter like the 2040). Comments?
> --
> john
> 
> 
> ----- Original Message ----- 
> From: "Rainer Buchty" <rainer at buchty.net>
> 
> 
> > >Also, I've seen the tricks used in the Xpander to
> get a variety of
> > >filter modes out of the 3372 (15 different modes
> with combinations
> of
> > >LP, BP, Notch and All Pass), and I was wondering
> if the same
> circuitry
> > >could be applied to the VCF in the 3396
> > >
> > >http://matrix-12.tripod.com/xpsvc26.jpg
> > >http://matrix-12.tripod.com/xpsvc27.jpg
> >
> > I wonder if it'd work with a 3328 and/or 3379 as
> well? Or was it
> just
> > the costs of the additional 6 OPs, the 4051, 4053,
> and passive stuff
> > which kept other synth manufacturers from using
> this neat circuitry?
> >
> > Rainer
> >
> 
>