[LAD] panning thoughts

Eric Kampman erickampman at me.com
Fri Nov 12 04:22:08 UTC 2010


I'm writing a synth module on top of jack and I'm starting to contemplate stereo.

I looked up "pan law" and understand that center should be -3 db (or some say -3.5 or 4.5, whatever) given unity at panned hard L or R. It was said that in an ideal room I should be down -6 db in the center.  That would mean linearly transitioning from unity gain to completely off as one pans, I *think* (-6 db in the center = .5).

So that's one (very easy) way to go...

There was also mention of "equal power". Since power is proportional to signal squared, this means with parametrized L and R functions

L(t)^^2 + R(t)^^2 = 1,    0 <= t <= 1

We need an f(t) such that f(t) = L(t) and f(1-t) = R(t).

I played around this for awhile and using the sum of the square of sin and cos etc I got an f(t) of

f(t) = cos( pi * t / 2 )        (details available on request)

So L(t) = cos(t * pi / 2) and R(t) = cos((1 - t) * pi / 2)

And that seems to work out correctly. 

Is this equal power version worth spending the processing cycles on? I intend to make pan envelope and LFO controllable so it's not going to be the case that the pan value can be thought of as relatively static.


PS now that I know what I'm looking for web search turned up this:

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