Synthacon Filter

Steiner Parker VCF

The Steiner VCF, also referred to as the Synthacon VCF, has recently become well-famed thanks to Ken Stone. In 1979, I came across the original article by Nyle Steiner (Electronic Design, 1974). I was seduced by the simplicity and low cost for such a versatile filter. I gave it a try and eventually built three of them. One was integrated in my very first modular synth (built in 1979-1980), and the two others were never incorporated in a synth...

I started a new modular project, and it appeared to me that I needed to include a few Steiner VCFs in it. But instead of using the original circuit I thought it would be interesting to design some variants of this fascinating filter. Eventually, I chose to build one around a CA3096 transistor array and a second one around a 2SC1583 dual transistor and a regular OPA.