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.

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

RemyRAD, post: 380111 wrote: ... But how many people listen in Mono these days?...

Everyone who listens to music on a laptop.

BobRogers, post: 380113 wrote: Everyone who listens to music on a laptop.

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

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

Of course they are all Mono with ceiling mounted systems. And that's why checking your Mono from your stereo mixes is so important. For these applications, we have to realize that " compromise " isn't a dirty word. But we don't listen in Mono we may hear Mono stuff in the background, at the restaurant, at the Wal-Mart. So I want our stereo to present a reasonable Mono down mix. And I think coming through ceiling mounted background systems that have usually been highly dynamically compressed wouldn't make a hoot of difference what you're panning Laws are at that point, at least not by much.

So panning laws are really quite a bit more applicable to stereo than to some watered down Mono rendition. What we are really after is stereo to mono compatibilities. And if your laptop Bob has only a single speaker it's time to get a new laptop. That is to say, not only did I purchase my HP laptop for its features, I still wanted to hear what it's little 1 inch speakers had to offer in comparison to other laptops. Since in a pinch, one might occasionally have to do some kind of minor little playback function for somebody through the laptop speakers.

And to an even greater extent, a stereo down mix from 5.1/7.1/10.2 to stereo when you listen to a movie on a DVD is still fraught with significant issues and problems and is a far more valid issue today than the panning laws with respect to Mono. TV stations & cable networks are the ones having the most problems with this because of the complaints from the consumers. You make it too complicated for the consumers and you will generate complaints. So all of the marketing nonsense for home theaters has created more problems than it has solved. If the movie industry did not release their DVD/blue ray movies I surround to begin with, it would give the public better reason to attend their local movie theater to watch & hear their movies in beautiful surroundsound. Most home listening environments really don't set up well for surround unless you're a rich guy with a beautiful home theater system. But that's the minority. Few people can set up their surround sound systems properly at all so why aren't we focusing on that more? It's because it's like quadraphonic that's why and people already have problems just placing 2 speakers in their listening environments at home. Another less is more issue.

I break all panning laws and have never been arrested for it, yet.
Mx. Remy Ann David