NE572 as VCA?

[The Dark force of dance]

Y-ellow Paul 'n' y'all.

At 10:14 PM 09/13/99 +1000, Paul Perry wrote:
>At 12:51 PM 13/09/99 +0200, Juergen.Haible wrote:
>
>>And, most important: Is it possible to link two halves of a 572 for stereo
>>compression ? I think it *should* be possible to hard wire the capacitor
>>pins together, i.e. pin 4 to pin 12, and pin 2 to pin 14, and only one set
>>of 2 capacitors. I've never tried it, 
>
>Neither have I, but it isn't obvious this would work.
>I'd sum the 2 channels, feed the two rectifier inputs.
>But, in the pathological case where the 2 channels are out of phase,
>thyere is naturally a problem.
>The data sheet makes unjustified assumptions about my intelligence..

You can feed the voltage/current  from one to the other. The
voltage/current appearing at the decay cap can be fed directly into the pin
of it's opposite number. Or something  like that. You'll have to mess with
it but there's  nothing surprising here. The output of the rectifier feeds
through a network across the two caps (pins) and the final pin is actually
the control input to the gain stage. So! In theory! If you link the two
together, you get dual  control.

Having said that. I've done this on the 571 but not the 572. But the 572
should be little  different apart from the attack/decay network.

Hope this helps.

Be absolutely Icebox.

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