Thanks Ken and everyone else who answered. That explains it
quite sufficiently. I was interested in fairly accurate tracking as
I'm interested in using the formants to "vocalise" the synth
sound, kind of like a poor mans vocoder. However, you've
convinced me not to bother...well, I might add a fourth band pass
with vactrols one day. Switching Opamps to OTAs is beyond my
ken, at the moment. Since I already have the PCBs from Ken,
and the components are in the post, I'll be quite happy with my
static filter bank (and VCO).
I like the sound of the MOTM 101, but I'm committed to the
Eurorack format for now. I'm building a 12U case which will be A
Sys/Doepfer compatable. Perhaps I'll invest in MOTM one day.
Once again, thanks for the replies.
Show quoted textHide quoted text
--- In cgs_synth@yahoogroups.com, sasami@h... wrote:
> The usual trick is to use OTAs instead of the op-amps to vary
the frequency,
> and as OTAs don't use the same physical or electrical
configuration, it
> would get ugly. Now if you are simply wanting to do the triple
resonant
> filter and don't care about accurate tracking, some possibilities
do open
> up. Basically, you replace the dual 100k pot with a pair of
vactrols in
> parallel with a couple of fixed 100k resistors. The current
through the LEDs
> will now control the frequency.
>
> Ken
>
> >Yep, they're definately terms that a newbie can understand...
> >I got the idea after looking at the Doepfer A127 triple resonant
> >filter. I'm not interested in the in-built LFOs, but I like the idea
of
> >being able to VC the freqs (talking synths). Is there a
technical
> >reason why the CGS30 isn't suitable for VC? (jut out of
curiosity,
> >Ken, I'll assume you know what you're talking about ; )
> >
> >Many thanks
> >
> >Stuadh
> >
> >
> >
> >
> >--- In cgs_synth@yahoogroups.com, sasami@h... wrote:
> >> I'd suggest building a different sort of filter if you want
voltage
> >control.
> >> It's kind of like asking how to add wheels to your motorbike
> >because you
> >> want a car.
> >>
> >> Ken
> >>
> >> >Hi list,
> >> >
> >> > I'm about to start building a 3 x band Pass filter + DC
mixer
> >as
> >> >shown on the website.
> >> >
> >> > However, can anyone explain (in terms that a newbie
might
> >> >understand) how to add voltage control to the frequency of
the
> >BP
> >> >filter. I'd like each channel to have this in addition to the
> >manual
> >> >control.
> >> >
> >> >Yours Aye
> >> >
> >> >Stuadh
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >See the following URLS for the CGS Modular Synth home
> >page:
> >> >Main: http://www.cgs.synth.net/
> >> >Secondary: http://otherunicorn.0catch.com/synth/
> >> >Yahoo! Groups Links
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >>
>
>_________________________________________________
_
> >_____________________
> >> Ken Stone sasami@h... or sasami@c...
> >> Modular Synth PCBs for sale
> ><http://www.blaze.net.au/~sasami/synth/>
> >> Australian Miniature Horses & Ponies
> ><http://www.blaze.net.au/~sasami/>
> >
> >
> >
> >
> >
> >
> >See the following URLS for the CGS Modular Synth home
page:
> >Main: http://www.cgs.synth.net/
> >Secondary: http://otherunicorn.0catch.com/synth/
> >Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
> >
>
__________________________________________________
_____________________
> Ken Stone sasami@h... or sasami@c...
> Modular Synth PCBs for sale
<http://www.blaze.net.au/~sasami/synth/>
> Australian Miniature Horses & Ponies
<http://www.blaze.net.au/~sasami/>
