[sdiy] multiplication thread

[Grant Richter]

It's really VT1-4, the inclusion of the Vactrol in the feedback loop
linearizes response and forces up the high frequency range. Vactrol
frequency response is around 5-35 milliseconds for a 5 decade change, but
small signal frequency response is greater.

Starting with US$24.00 worth of Vactrols, ANY other circuit is cheaper than
this one.

From: mark verbos <mverbos at earthlink.net>
Date: Fri, 25 Apr 2003 05:38:05 -0500
To: jhaible <jhaible at debitel.net>
Cc: synth DIY <synth-diy at dropmix.xs4all.nl>
Subject: Re: [sdiy] multiplication thread


it's like a crossfader between the signal and an phase inverted version of
the signal. There are vactrols in the feedback loop of the control circuit,
which I have been told linearise and speed up the response. There is also a
vactrol based crossfader between the dry signal and the balanced modulated
one, just like in the Serge, etc.

Sounds good, I didn't think it would either.

check it out 
http://www.takeonetech.de/buchi/magnus/synths/companies/buchla/Buchla_2080_5
_200.jpg

mark



jhaible wrote:
Did he really use the Vactrol for the audio rate multiplication,
or for wet/dry mixing (like Korg) ?

JH.


-----Ursprüngliche Nachricht-----
Von: mark verbos <mverbos at earthlink.net> <mailto:mverbos at earthlink.net>
An: synth DIY <synth-diy at dropmix.xs4all.nl>
<mailto:synth-diy at dropmix.xs4all.nl>
Gesendet: Freitag, 25. April 2003 12:02
Betreff: Re: [sdiy] multiplication thread


don't forget the Buchla 208 one made from Vactrols! It only has one
trimpot. I built one and it sounds good to me.

mark



Czech Martin wrote:

sorry if I disturbed people with this long thread!
Thanx for all the responses.
So I got the following homework to do:

1.) dual OTA ringmod (13700)
2.) RC4200 ringmod
3.) single OTA ringmod
4.) 1495 ringmod
5.) discrete ringmod (finished)
6.) 1496 with predistortion ringmod
7.) real ringmod with transformers
8.) real ringmod with opamp balancing
9.) 633 ringmod (finished)


To be realistic, this won't be finished before summer vacations.
Perhaps a little earlier.

m.c.















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