[sdiy] Article "Analyzing the Moog Filter"

Donald Tillman don at till.com
Thu Aug 22 22:51:40 CEST 2019

I think he's got a point.  How many filter topologies are there that are analog, audio range, and accurately voltage controlled over a substantial range?   I count two.

The Diode Ladder is essentially derivative of the Moog, even though it works differently.  

There are VCFs based on the Sallen-Key, or any other active filter topology, hacked up for voltage control, sure.  Though they have less precise tuning.

In practice, don't the Moog Ladder and the State Variable account for 95% or more of the filters used in synths?  What am I missing?

I have several filter topologies of my own, of course, so I'm not saying there are inherent limitations or anything.

  -- Don
Donald Tillman, Palo Alto, California

> On Aug 22, 2019, at 12:52 PM, Kylee Kennedy <kmkennedy at gmail.com> wrote:
> Honestly it was hard to get past "Learn about one of the only audio filter topologies out there, the Moog filter!"
> Kylee
> On Thu, Aug 22, 2019 at 12:33 PM Ian Fritz <ijfritz at comcast.net <mailto:ijfritz at comcast.net>> wrote:
> Not many synth filters? That could make many people unhappy. Oh well 
> it's just a kid.
> Ian
> On 8/22/2019 12:51 PM, Ingo Debus wrote:
> > Anyone seen this?
> > https://www.allaboutcircuits.com/technical-articles/analyzing-the-moog-filter/ <https://www.allaboutcircuits.com/technical-articles/analyzing-the-moog-filter/>
> > https://www.allaboutcircuits.com/technical-articles/small-signal-open-loop-transfer-function-moog-filter/ <https://www.allaboutcircuits.com/technical-articles/small-signal-open-loop-transfer-function-moog-filter/>
> > 
> > Ingo
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