Odp: [sdiy] diode war

[harrybissell]

Au Contraire mon frere....

If you use a dual Vactrol, or a center-tapped element Vactrol... it
is possible to get VERY linear operation (maybe good enough for
VCO ?) by using the LED and 1/2 the device in an opamp feedback
circuit, and the other half in the synth.

National Semi called this an "analog multiplier" in their Linear Apps
handbook... check it out.

H^) harry

mark verbos wrote:

> One idea I have had is to make certain "theme synths" where the voltage
> control element is the same in every module. The idea came up first for
> Vactrols. Then you quickly realize that a Vactrol VCO will not track
> very linearly. However, the all diode synth is still something I think
> about form time to time. You could make VCAs and VCFs with diode rings,
> why not VCOs and Envelope Generators with the same rings? Just a thought.
>
> all diode source of uncertainty......
>
> mark
>
> Roman wrote:
>
> >Hi Dave,
> >I have an affection for zener diodes. I use them everywhere.
> >Small voltage diodes, those below 5V trip point, have rather
> >smooth transition comparing to the 'bigger' ones.
> >My tri-to-sine converter is made from 2 2V7 diodes.
> >I used 4V3 (?) zeners in integrator feedback to prevent my
> >filters from going crazy when opamp clips.
> >
> >BTW, using diodes and other stuff in feedback loop is
> >is 'goal of life' for my friend, Maciej Bartkowiak, who's
> >also on this list, I think. He's preparing to make some
> >killer synth using variable distortion.
> >
> >Roman
> >
> >----- Original Message -----
> >From: Dave Krooshof <synthos at xs4all.nl>
> >To: <synth-diy at dropmix.xs4all.nl>
> >Sent: Monday, October 07, 2002 10:22 PM
> >Subject: [sdiy] diode war
> >
> >
> >>Y'ellow Y'all,
> >>
> >>I am experimenting with clipping/distorion etc. In the basics
> >>it's just an opamp with two diodes anti-paralel in the feedback loop.
> >>Or, like in the big muff, three diodes in series in both directions.
> >>->>>-
> >>-<<<-
> >>I like the simple design, as it is the clipping component that reveals
> >>its audio qualities this way. I tried several of the diodes I had
> >>about the house.
> >>
> >>[black] I first had two black ones (no type #, sorry): Familiar fuzz sound.
> >>Then I tried 3 by 3 regular standard diodes (those orange glassy ones that
> >>open @ 0.7 volt), like the big muff does. That's relatively sweet/warm,
> >>I imagine that this is due to the fact each diode opens up slightly
> >>different.
> >>
> >>[blue] I now have blue LEDs in them (open @ 1.5 volt), they sound fairly
> >>
> >clean.
> >
> >>That is: this is just clipping, not a distortion. Cool as in not warm.
> >>
> >>[red] I'll make a switch to hook the semi-transperant light-red LEDs in again,
> >>as those sound crazy in the midrange. Wow!
> >>
> >>             So the QUESTION is:
> >>             What's _your_ favourite clipping component?
> >>
> >>Any experience with the expensive LEDs like IR and bright-white
> >>for the purpose of clipping?
> >>
> >>Dave
> >>--
> >>
> >>--
> >>
> >>
> >http://pages.vpro.nl/3voor12/journalism/index.shtml?2534202+2584688+2584508+7333
> >367
> >
> >