[sdiy] anyone have a vc pan circuit?

[Grant Richter]

Sorry, I was describing a "segue" or crossfade module.

The math is the same for panning with linear VCAs.

x = input

Out1 = pan * x

Out2 = (1 - pan) * x

For pan = 0 to 1

The 0 to 1 could be made 0 to 10 with scaling adjustments.

A simple switch jack would allow both functions in the same module.
Normal the second input to the first. Then provide a summed output.

Use two inputs and the summed output and it is a segue (crossfader).
Use the first input and two outputs and it is a panner.

Just too simple to think of I guess.

On May 3, 2006, at 11:45 PM, Grant Richter wrote:

> Just take two linear VCAs and a voltage inverter with offset.
>
> The math is: Out = (segue * x) + ((1 - segue) * y)
>
> For seque = 0 to 1
>
> You only need equal power correction for Log VCAs. Linear VCAs work  
> correctly without any compensation.
>
> John Blacet failed to do this with his Dual Linear VCA, which is an  
> ongoing tragedy.
> He would probably sell many more if they were prepatched as  
> crossfaders and not their current opaque prepatch.
> A switch is just a crossfader driven with a square wave.
>
> A crossfader is the most important part of a DJ mixer, and kills in  
> a modular too.
>
> On May 3, 2006, at 3:26 PM, Jason Proctor wrote:
>
>> i'm thinking of putting together an affordable equivalent to the  
>> serge QVM module. i can pretty much hack together the vc mixer  
>> stages etc but i don't have a real vc-pan circuit handy. anyone  
>> have one that does the right centre attenuation etc?
>>
>> thanks all