[sdiy] Control law for crossfader/panner

[Byron G. Jacquot]

>just a quickie question: What would be the preferred way of doing 
>crossfading between two signals?
>
>Basically I would like to fade Signal 1 from channel A to channel B, 
>while signal 2 wanders from B to A. Would you put the half power, i.e. 
>-3dB at the center or rather half amplitude, -6dB. And how to go in 
>between? Linear VCAs or exp VCAs?

As for the tapers, it really depends on the nature of the signal, and how you want the control to respond.

The half-power/half-amplitude at the center (and the related "compromise" of -4.5 dB at the center) is useful for stereo work, where the result needs to have some correlation the input.

However, in applications like a DJ mixer, it might be more useful to have the curves be nearly flat from one end to the center, then taper quickly once the center is crossed.  This lets you "morph" one input into the other, without the program getting quieter as you approach the center.  Some of the fancier DJ mixers actually let you adjust the taper.

Isn't the VCA response really determined by the response of the CV being employed?

Byron Jacquot