OT:stereo channel pan pot behaviour

On another board, I’m engaged in a discussion about the preffered behaviour of the pan (balance) pot of a stereo input channel.
More specifically about what the output level should be with the pot centered, fader at unity gain and 0dB signal at the inputs.
I think both channels should be at 0dB in this case, but valid arguments have been made for other levels.
To broaden my scope on the matter, I want to ask you all this question:

What do(es) your mixer(s) do?

When you are speaking of Stereo channels, are you speaking of Discrete stereo or a Mono signal on a Stereo stream?

Dave T2

I’m speaking of the channels that will take a L/R stereo signal for input (as opposed to those that take a mono signal and pan it into a stereo position).

In the case of n-Track, mono/stereo doesn’t matter – both are handled the same way.

n-Track keeps both sides at 0dB when centered, and reduces the opposite side as you pan. This is the way all mixers I’ve used work, and I like it best. However, the operator has to realize that panning affects volume, and adjust accordingly. But frankly, after panning, a volume adjustment would be necessary regardless – because you’ve changed the mix.

But mono/stereo does matter when discussing pan laws. It’s best to discuss both rather than just one or the other, to keep things in perspective.

There is a constant total volume pan law for uncorrelated stereo tracks, and one for mono tracks. Neither is a constant total volume pan for typical stereo tracks, which are “mostly correlated”. (“Uncorrelated” means that the left and right have nothing significant in common. In typical stereo tracks, low frequencies are very correlated, and high frequencies are generally uncorrelated except for attacks.)

The difference between the two is that the law for mono has a 6dB cut in center position, because duplicating a mono track adds 6dB of volume, whereas for uncorrelated stereo, you only want a 3dB cut (because adding two uncorrelated tracks causes a 3dB volume boost).

And so, there is also a compromise that uses a 4.5 dB cut in center position.

I suppose someone could create a crossover-pan, that treats the low frequencies like mono and high frequencies like uncorrelated stereo, that would keep the volume pretty constant for typical stereo signals. But I don’t like the idea of inserting a crossover in the signal just to pan.

No doubt there are other pan laws I don’t know about. And perhaps there are technical terms for the kinds I mentioned above, but I don’t know them.

I like knowing that in center position, NO CHANGES are being applied to the signals. So I like how n-Track works. This sure simplifies things when doing lab experiments, like figuring out dithering settings and the investigations it took to produce the signal path diagram.

Another option for stereo is to have two mono pan pots. This is equivalent to splitting the stereo track into two mono tracks with two mono pan pots (though again, there would be at least two varieties: constant volume or zero-cut). This kind of thing is often quite handy. For example, the samples for the stereo piano sound I usually use were recorded from the player’s perspective, so higher notes are louder on the right, lower louder on the left. But I usually like to put piano on the left side of the soundstage (that’s where a grand is on a real stage, due to the way it opens – if it’s not in the center). Panning left, I lose the high end, which is the opposite of what I want. It’s better to pan the left channel far left, and pan the right channel near center. To do this, I have to split the stereo track into two mono tracks.

But I don’t think I’d want that on every track. I usually prefer the simple pan pot just as it is. It would be nice to be able to right-click and select dual-pot panning, but I won’t hold my breath!

Some sequencers let you choose a preferred panning law. Like Jeff though, I like the way n-Track works and have set my other packages to operate on “Equal Power” pan laws. It’s been so long since I changed 'em I can’t even remember what Steine and Cakewalk call all the optional laws. ???

D

Jeff, thank you for yet another in-depth and very instructive reply.

Diogenes, could you explain why you set all your other packages to equal power pan laws, while you’re saying that you like the (non-equal power) way that n-Track works (or maybe I’m misinterpreting what you want to say)?

Eh, I think I did not say what I meant. I fiddled with Cubase and Sonar LE and Magix until they worked like n-Track. I think my terminology is mixed up! :)

D

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I can’t even remember what Steine and Cakewalk call all the optional laws.
:)

Learjeff, got that in the wiki yet?

No, but feel free to paste away! :)

No shortage of stuff to post. I think I’ll take a good whack at “getting started” soon.

The thing is, answers to specific questions are a lot easier (for reader and writer) than generic advice posted for all eternity. Well, for the next year or so, which is about the same thing on the web!

SO long as the thing is searchable and organized… I would expect to see a ton of links over there. No need to keep it general.

Believe me, Bubba, I’ve written plenty of documentation and FAQs and etc.

It’s a LOT easier to answer a specific question that to address a particular subject. And just saving all the answers to all the questions isn’t that helpful – you already have that here. So, the ideal thing is to post slightly more general things than just repeating answers to specific questions found here.

Of course, there are lots of questions that aren’t terribly specific and still have good answers, plus real specific questions that come up a lot.

But that’s the difference between a forum and a Wiki or tutorial site. On a forum you can ask a very specific question and get pointed advice. On a Wiki/tutorial, you get a wider view, but you have to look a bit harder to find it. And more comprehensive info can go there, since it’s the kind of thing where you can keep adding info and refining, as opposed to individual answers to forum questions.

I confess I get annoyed when someone asks a specific question and someone answers “rtfm” or “rtfs” (s = site). It’s often HARD to find answers in documentation and websites, even well-organized ones. (I see that more at another site I haunt than I do here.)