Steiner-Parker? Other diode filters?

Sean Costello costello at
Thu Jul 16 19:12:04 CEST 1998

Hi all:

Does anyone out there have any Steiner-Parker schematics?  The
description of these synths sounds interesting.  In particular, anyone
know how the filters work?

On a related note, Nyle Steiner has an article in Electronic Design #25,
from Dec. 6, 1974, about a "simple low-pass, band-pass, high-pass
structure using dynamic resistance of diodes."  Time to head to the
University of Washington again to check out the Engineering Library.

On a less related note, I went to the UW Engineering Library yesterday
to look up info on nonlinear oscillators in music.  Several interesting
papers came out of one N.H. Fletcher, from Australia (lots of cool stuff
about nonlinear mechanisms in gongs and cymbals).

On a more related note, does anyone else out there know of synth VCF's
that used diodes as the control voltage element (as opposed to the
transistors in the Moog design)?  I know of only a few:

EMS VCS3/Synthi
Roland TB-303
Korg MS-50 (these three can be seen at
Practical Electronics Minisonic

What other synths used diode filters?  I suspect the Steiner-Parker
synths used these (perhaps in a state-variable configuration). Did some
of the older Rolands use diode ladder filters?  Didn't PAiA use diodes
in some of their filters?

Once again, any and all info appreciated.  You folks have helped me a
lot lately.


Sean Costello

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