[sdiy] What would be THE best, most versatile VCF available on DIY community ?

[ChristianH]

On Tue, 29 May 2012 23:24:40 +0800 David G Dixon <dixon at mail.ubc.ca> wrote:

> > this is something that has long bothered me...when looking at 
> > schematics that use the CEM chips or SSM chips, is it 
> > possible to simply transfer the entire design to OTA's? 
> > (13700s) or is there some sort of MAGIC (something in the 
> > patent?) in those chips which makes them hard to copy?
> > 
> > for instance.....the Anderton Multiple Identity 
> > Filter...could you make the same thing with OTAs? in his 
> > introduction he mentions making it with SSM chips instead of 
> > CEM chips...I took that as a good sign.
> 
> There's no magic.  Any filter can be made with OTAs and buffers (or VCAs and
> integrators).  The key (and I say this not to sound like a pedantic jerk,
> but simply because it is true and never fails if you know how to use it) is
> to derive the transfer function of the filter you're trying to emulate and
> then use algebra to figure out where to put the various inputs and outputs
> and feedbacks in your own version of it.

Wasn't there some pretty asymmetric distortion going on in the SSM 2040?
I never really cared for the internal circuitry, so I'm not quite sure
what it was about.

Yuck, where is JH when you need him... :-(

Chris