[sdiy] vactrol panning (across 4 outputs?)

[alfred.pear at gmail.com]

Hey Karl-

Nice box - a little bit out of my price range, especially since I need two.

I was actually using a joystick with an LED attached under the
chassis, that would shine onto partitioned photocells - but alas, no
CV, which is really what would be ideal.

Can you say anything about scaling the CV across several VCAs or is
that top secret?

-AP

On Sun, Jan 16, 2011 at 10:45 AM, Karl Ekdahl <elektrodwarf at yahoo.se> wrote:
> 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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