[sdiy] 2164-based SVF [was: Re: SEM filter questions]

[Tom Wiltshire]

On 23 Apr 2012, at 17:33, David G Dixon wrote:

>> Here is Motohiko Takeda's example:
>> 
>> http://www.aleph.co.jp/~takeda/radio/harvest/img/schem/ssm2164
>> -schem.gif
> 
> This one is interesting too, as he has put the limiting diodes on the input
> summer, and has used the spare pair of VCAs as a linearized VCA, and used a
> JFET to provide VCQ.  There seems to be a very large variety of approaches
> to handling the resonance.  Someone should do a comparison...


Another big thumbs up from me for Motohiko Takeda's lovely example. A filter/VCA combination in only 3 ICs appeals to me. With that schematic, you're halfway to a Oberheim synth voice.

All SSM2164 SVF filters are basically the same, except for the resonance and the limiting. This one has a interesting treatment of the resonance (love the JFET) and the limiting on the first mixer stage with LEDs is very novel too. Great work.

About the only thing I'd want to see additionally is some way to get at the other responses.

Tom