[sdiy] 32 Stages of Vactrol Phase Shift

[scottnoanh at peoplepc.com]

Hi Pete,

Thank you very much!

Absolutely - I intend to post all the info about it, including schematics.
I'm still nailing down what I want to put into it, but I think I'll start
posting the basic blocks of it - really, if one wanted to build it, it could
be customized to what one wants to build.  In fact, there's so much I want
to do with it, I'll have to choose what I like most - otherwise, the panel
will end up being as large as a Packard.

There's nothing terribly complicated about it, just a lot of repetition (32
stages), but it certainly is fun.  The idea is to allow the the regen and
wet signal to be tapped from any even stage, individually, and inserted into
the first stage (even number of stages) or the second stage (odd number of
stages).  Some guy by the name of Moog did this with his original rack phase
shifter (except he kept the regen/signal insertion point fixed at even
number of stages).

With this setup, being able to mix and match wet signal and regeneration,
one can get an absolutely gigantic range of effects out of it!

On the regeneration line, I'm using a That Corp. designed soft knee
limiter/compressor that really sounds nice in this app.  I have the phase
shifter divided into two 16 stage sections because that's about all the
current modulation circuit can handle - it's just an ARP style expo sink
made up of an NPN/PNP transistor pair.  Ripped directly off of Rene
Schmitz's VCO4069, in fact =0).  Right now, I'm just using my quad LFO
module to drive it - they're Ray Wilson LFO's.  The hypertriangluar waveform
that I use for faster modulation rates is rendered by driving a triangle
through a FET distortion circuit.

I've started a page that badly needs updating here:

http://mypeoplepc.com/members/scottnoanh/birthofasynth/id18.html

I'll post to the list when I've added the latest info.

Take care,
Scott

----- Original Message -----
From: "Pete" <23isgood at gmail.com>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Friday, April 14, 2006 5:54 PM
Subject: Re: [sdiy] 32 Stages of Vactrol Phase Shift


Very very nice! Are you offering any info on how to build it? Schematics?

pete


--
www.cubanpetemusic.com