[sdiy] all analog FM synthesis?

[Don Tillman]

   > From: "JH." <jhaible at debitel.net>
   > Date: Tue, 1 Mar 2005 13:39:05 +0100
   >
   > > Instead of VCO he is using self oscillating moog ladder filters.
   > 
   > How do you modulate an oscillating filter thru zero ?

Hey JH!

>From the description at http://www.jayemsonic.de , I'm guessing that
the Neuronium synthesizer ladder filters are not thru-zero devices.

The only thru-zero VCF I know of is by Henry Walmsley; he uses it as
an oscillator for his frequency shifter.  It's basically a forward
biquad filter and a reverse biquad filter spliced together:

http://homepage.ntlworld.com/henry01/frequency_shifter/frequency_shifter.htm

It may be possible to do something similar with a ladder filter.

  -- Don

-- 
Don Tillman
Palo Alto, California
don at till.com
http://www.till.com