[sdiy] vactrol panning (across 4 outputs?)

[Karl Ekdahl]

I realize that this might not at all be interesting and it *is* shameless self-promotion, but nevertheless...

http://www.knasmusic.com/products/quadmassager/quadmassager.php

Karl

--- Den sön 2011-01-16 skrev alfred.pear at gmail.com <alfred.pear at gmail.com>:

> Från: alfred.pear at gmail.com <alfred.pear at gmail.com>
> Ämne: Re: [sdiy] vactrol panning (across 4 outputs?)
> Till: "Tom Wiltshire" <tom at electricdruid.net>
> Kopia: synth-diy at dropmix.xs4all.nl
> Datum: söndag 16 januari 2011 15:08
> Tom -
> 
> I was under the impression that a scanner shifted from
> inputs, rather
> than sent a single input to multiple outputs - so I'm
> apologize for my
> lack of clarity...
> 
> The goal is a circuit that will take one inputs and "pan"
> it across
> four outputs, one by one, with a single voltage, preferably
> in a
> compact design similar to the simple panning implementation
> (sorry
> Aaron).....
> 
> I was hoping there might be a way to put a current mirror
> inside the
> current mirror...but I don't really know..
> 
> -M
> 
> 
> On Sun, Jan 16, 2011 at 8:24 AM, Tom Wiltshire <tom at electricdruid.net>
> wrote:
> > Sorry Alfred, I'm not quite clear what you're trying
> to do.
> >
> > Do you want the two extra channels to be copies of the
> existing two channels, or are you aiming to build a
> 'quadraphonic' version of the circuit?
> > Or do you have a 'four channel scanner' circuit in
> mind, where the output can be 'panned' from output 1 to
> output 2 to output 3 to output 4 under the control of a CV?
> >
> > The circuit itself looks to be a pair of "optical"
> VCAs, as used in many famous compressor designs (very simple
> audio path, so low noise, and the slow LDR response gives a
> natural sound). The vactrol's LEDs are driven with a current
> mirror, which provides the panning action (one goes up
> whilst the other goes down).
> >
> > Thanks,
> > Tom
> >
> >
> > On 16 Jan 2011, at 05:00, alfred.pear at gmail.com
> wrote:
> >
> >> hi synthesists -
> >>
> >> i'm sure many of you are familiar with this very
> elegant two-channel
> >> panning circuit, using two vactrols (based on a
> buchla design,
> >> apparently):
> >> http://www.simple-answer.com/vac-panner.jpg
> >>
> >> i feel like there must be a way to nest and scale
> several transistors
> >> in there to make this circuit response across four
> channels of
> >> output....but i'm not a very skilled designer..
> >>
> >> any suggestions?
> >>
> >> sincerely,
> >> a. p.
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> >
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