[sdiy] Looking for 2164 12db/oct slopes bandpass filter design.. more detailed..

Jean-Pierre Desrochers jpdesroc at oricom.ca
Sun Mar 9 17:39:38 CET 2014


Roman,

You are right when you say your design does HP and LP separately
with their own CV's controls.
But you are using 2 x 2164 in your design to do so (because you also do BP).
My approach here:

Here is a possible 2 x 2 poles, 12db/oct bandpass design made of one 2164.
http://www.arcenson.com/public/2164_BP_filter.JPG

But thanks for sharing..

JP

-----Message d'origine-----
De : synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] De la part de Roman Sowa
Envoyé : 9 mars 2014 01:04
À : synth-diy at dropmix.xs4all.nl
Objet : Re: [sdiy] Looking for 2164 12db/oct slopes bandpass filter design..
more detailed..

why not take a look at "the classics", now almost 14-years old design, which
among other things, does exactly that - chains 2 state variable 2-pole
filters, one HP, one LP, with control for the gap size.

http://sowa.synth.net/modular/vcf.html

just replace 2164 cell with other OTA in the feedback path so to need only
one 2164 for both filters.

Roman

W dniu 2014-03-08 17:46, Jean-Pierre Desrochers pisze:
> In fact I should have been clearer on my needs..
> I'm looking for a 2164 based  bandpass filter design Built with one 
> separate 2 poles lowpass (12db/oct) (2164 section #1+2) In series with 
> one separate 2 poles highpass (12db/oct) (2164 section #3+4).
> These 2 blocks in series  make it possible to feed 2 separate & 
> different cutoff CV's Thus having the possibility to open or close a 
> 'gap' between the cutoffs Creating a variable bandwidth for the 
> overall bandpass filter CV controlled.
> That's why I cannot use a 'derivated' bandpass from a lowpass design 
> using pole mixing because the cuttof freq would be the same All around 
> the 2164 blocks..
> I'm only looking for schematics of:
> -2 poles 2164 based lowpass filter (12db/oct slope)
> -2 poles 2164 based highpass filter (12db/oct slope)
>
> Your ideas are welcomed.
> J-Pierre
>
>
> -----Message d'origine-----
> De : synth-diy-bounces at dropmix.xs4all.nl
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] De la part de Jean-Pierre 
> Desrochers Envoyé : 7 mars 2014 11:34 À : synth-diy at dropmix.xs4all.nl 
> Objet : [sdiy] Looking for 2164 12db/oct bandpass filter design..
>
> Looking for 2164 based 12db/oct bandpass filter design..
>
> Any web link ?
>
> Thanks
> JP
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