[sdiy] Band-Pass Filter with CV control of Frequency Cut-off?

[Tom Wiltshire]

I don’t know if it helps Justin much, but that’s an awesome idea in its own right even if it doesn’t!

After all, the whole point of the circuit is that it’s just controlled by a single-gang 100K pot. So…one vactrol, or maybe even a FET?

==================
       Electric Druid
Synth & Stompbox DIY
==================

> On 31 Mar 2018, at 16:41, Quincas Moreira <quincas at gmail.com> wrote:
> 
> maybe adapt the Crybaby filter to use CV?
> https://www.electrosmash.com/crybaby-gcb-95
> 
> On Sat, Mar 31, 2018 at 9:16 AM, Tom Wiltshire <tom at electricdruid.net> wrote:
> If you want CV control with no vactrols, you’re looking at an OTA or VCA. If you want bandpass, it’s going to need two slopes, so you need two OTAs or VCAs. In short, it’s not going to be *much* less complicated than the SVF.
> 
> I guess you could do it with one VC-LPF stage followed by one matching VC-HPF stage. That might be somewhat simpler than a full SVF. THAT2162 is a nice dual VCA which would give you exponential control. They have an application note showing the construction of different filter stages with their VCAs:
> 
> http://www.thatcorp.com/datashts/dn130.pdf
> 
> HTH,
> Tom
> 
> ==================
>        Electric Druid
> Synth & Stompbox DIY
> ==================
> 
> > On 31 Mar 2018, at 13:14, Justin Owen <juzowen at gmail.com> wrote:
> >
> > Hello,
> >
> > Can anyone point me to some schems of a reasonably simple, analogue band-pass filter with CV control over the frequency cutoff - that *isn't* the well-established two pole multi-mode architecture and I guess - at the other end of the scale - isn't a passive filter with the resistor/s replaced by a vactrol.
> >
> > I'm looking for something to use as part of a feedback effect I've been tinkering with - so I don't need anything too fancy or highly-specced but the standard two pole multi-mode is currently more complex than my needs.
> >
> > Is there such a thing?
> >
> > Thanks!
> >
> > / Justin
> >
> >
> >
> >
> >
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> -- 
> Quincas Moreira
> Test Pilot at VBrazil Modular