[sdiy] Ken Stone Synthacon VCF?

[Luís Marka]

I built one to see how it sounded. Immediately after I built two more, and I
am about building other two! There are a few errors in the schematics:
replace the 10k resistor in series with the Res potentiometer with a 1k one,
and reverse the 10uF electrolitic capacitor connected to the colector of
2N2907. In my prototypes I replaced the two 2N2222 connected to CV with
2N3904s, because the 2222s had not enough gain. And it would be nice to put
CV attenuators with reverse action, like this:
http://www.buzzclick-music.com/gizmotron.html. I also increased the output
gain, replacing the 47k resistor between pins 6 and 2 of TL071 with a 100k
one. And if you want a nasty resonance, up to distortion, replace the 1k res
pot with a higher one. 2k2 should be enough, depending on the gain of your
transistors.

How it sounds? In one word: Electronic. I think it's a wonderful filter,
made out of cheap parts (I built the first prototype mostly out of parts
taken from a few burned PC power supplies!). Go and build it, man! It's very
well worth the effort.


----- Original Message -----
From: "Thomas Kahn" <thomas at roundhouse.se>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Tuesday, March 25, 2003 8:06 AM
Subject: [sdiy] Ken Stone Synthacon VCF?


> I'm interested in building Ken Stones version of the Steiner Parker
> Synthacon VCF. Since there are no boards for sale I guess I will have to
> build it on veroboard. There is a schematic on the site and an image of
> the board with a printed overlay. I'd like to have a "clean" version of
> the board as well (without the overlay, just the circuit traces). Does
> anyone have this?
>
> Since I'm asking about this - has anyone built it? Does it sound nice?
> Do you use it a lot?
>
> /Thomas
>
> Thomas Kahn
> Maaki webbkommunikation
> thomas at maaki.com
> Tel: 08-545 210 03
> Mob: 0704-22 66 44
> http://www.maaki.com