[sdiy] Ray Wilson Filter question

[synth at oldmail.charlielamm.com]

At the risk of sounding dense....I'm having trouble visualizing this
1M/1K mod....Do you mean run a 1M resistor from IC-2B pin 14 to ground, in
addition to what's already there?


> Adding a 1M resistor to this input (ie 1M / 1K divider) will allow
> you to add
> a trimming voltage to reduce the DC offset as well !   From my experience, you
> need only
> add the trimmer to one stage.
> 
> H^) harry
> 
> synth at oldmail.charlielamm.com wrote:
> 
> > I am trying to use this Ray Wilson filter in something I am building:
> >
> > http://www.musicfromouterspace.com/analogsynth/statevariablefilter.html
> >
> > I am using +/- 15V instead of +/- 12V.
> >
> > I am also using mod CV of 0 to 5V--the circuit looks to me like it expects
> > 0-10V for a good sounding filter freq sweep?
> >
> > To make this work, I think I need to change R6 to about 47K for the 0-5V
> > CV for freq mod, and R14 to about 180K to accommodate the greater supply
> > V's.  I can't think of any other mod necessary.
> >
> > Can anyone else?  Are my subs OK?
> >
> > Thanks in advance for any help.  --Charlie Lamm
>