Pan Laws Explained

Discussion in 'Recording' started by audiokid, Dec 4, 2011.

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1. audiokidStaff

A detailed explanation on pan laws would be very helpful for years to come. Thank you for your contribution on this subject!

2. bouldersoundReal guitars are for old people.Well-Known Member

If panning were done by simply turning down one side you would end up with a perceived loss of level when you pan away from center and an increase as you panned back to center. Pan law refers to the amount the signal is lowered as you pan toward the center to maintain a constant perceived level. A common pan law is -3dB at center, but playback circumstances vary so -3dB is only one approximation used. Other common pan laws are -2.5dB, -4.5 and -6dB at center.

3. BobRogersWell-Known Member

I can't give a detailed explanation because I don't have a detailed understanding of the curves used. However, here is the basic idea. The "intuitive" way to design a pan circuit for a mono signal is with a linear pot. When the pot is all the way to the left the full signal is in the left speaker and there is no signal in the right speaker. When the pot is all the way to the right the full signal is in the right speaker and there is no signal in the left speaker. When the pot is in the center half the signal (-6 dB) is in the left and half the signal (-6 dB) is in the right. Only one problem. In a real room this doesn't work. Because of reflections, we perceive the hard paned signals as louder than the centered signal. To get the centered signal to be perceived as loud as the panned signals we need both left and right to be louder than -6 dB. Disney did early tests and decided -3 dB. The BBC has more recent tests and said -4.5 dB. (Obviously, the "right" value depends on the room.) So instead of a straight line that goes from 1xSignal to 0xSignal in the left speaker as the pan knob goes from left to right (with -6dB in the center) we have a smooth, concave down curve that is -2.5 or -3.0 or -4.5 dB in the center. I don't know the formulas that they use for the curves.

These panning laws really only come into play when you are panning an instrument from left to right or, right to left as an effect. It really doesn't hold up or make any difference if you are merely positioning instruments into fixed localized positions without without panning them back and forth. These panning laws are also more applicable to Mono/monaural playbacks of stereo mixes of guitars sweeping back and forth in the stereo image. In Mono, you wouldn't want those guitars flying from left to right or vice versa to include sudden increases in level when going past the center 12 o'clock position. And that's why they build in a certain amount of loss to prevent that aberration from happening. But how many people listen in Mono these days? Not many. I just do that to check my mixes for aberrations in level & phase cancellation. I also know some Gold Record engineers who don't give a crap about checking their mixes in Mono because they're not intended to be listened to that way. While I have dealt with television broadcasts so much where the sound is coming out in Mono through a 3 inch speaker. So that's important to me even if I'm just mixing music for a CD release. I want my stuff to sound just as good in Mono as it does in stereo because that's important to me.

To each their own or from the advice of others
Mx. Remy Ann David

5. BobRogersWell-Known Member

Everyone who listens to music on a laptop.

6. bouldersoundReal guitars are for old people.Well-Known Member

My laptop has two speakers. I know because I can hear things panned. It may not be the pinnacle of stereo imaging but it's much more stereo than mono.

Lets face it guys, 1 inch laptop speakers while still stereo, frequently appears without much discernible stereo effect. On a decent pair of control room monitors though, things can get ugly if one doesn't keep track of their phase variables and flying guitar tracks sweeping back and forth and so, panning laws were initiated.

Which way did they go? Which way did they go?
Mx. Remy Ann David

8. audiokidStaff

re mono: How about malls and public sound systems. Aren't they all mono?