Minimoog VCF

[Sean Costello]

Terry Michaels wrote:
> 
> I have seen several reports that the Minimoog filter circuit available on
> the web contains errors. Does anyone know if this is really true?  I have a
> good print of the Minimoog schematics I got directly from Moog, if anyone
> is willing to host the filter circuit on their web site, I will scan it and
> email it to you.  That should put to rest the "Minimoog filter circuit with
> errors" problem once and for all.

I have a scan of the Minimoog circuit on my web site
(http://www.seanet.com/~costello) that is also up at Harmony Central.  I
had made some corrections to the schematic; at one point I thought that
they might be in error, but I think that the schematic is actually
correct as it stands.  The changes I made were to obvious errors in the
revised Minimoog schematic I scanned in.  I based the changes on an
earlier Minimoog filter schematic that was in my schematic set, as well
as a hand-drawn version of a Gene Stopp circuit that made the rounds
around 1996.

I could never get that circuit to work, or any other ladder-type filter
- the only filter I managed to get working was a 13700-based 4 pole
filter based on a design in Electronotes #41.  I may try to get an MS-20
filter working one of these days, but I am pretty busy with Csound and
other computer music things right now.  I haven't touched my analogs in
months.  Anyone want any x0x boxes? (I sure ain't gonna sell my Moogs or
Octave Cat, though).

Sean Costello