LCR Mixing

[flextone]

I've been seeing this term thrown around for some time and after reading up I'm still not sure what it means exactly. Here are my questions.

I understand that LCR mixing means I need to pan every channel either hard L/R or to the center. Are these absolute values or can center also mean -2L for example?

What should I do with stereo tracks? Just center them? Perhaps separate them into mono stems, pan each one hard L and hard R respectively and use the volume faders to position them in the stereo field? Or does this defeat the purpose of LCR?

What about stereo effects etc, how do I go about working with that in LCR mixing?

Thanks.

[bkshepard]

LCR came about primarily for the film folks to keep the dialogue in the center directly behind the screen. It also helps maintain a "center" to the sound when you are positioned off to the side--the point where a "phantom center" would normally disappear.

You can certainly do pans between those three positions. You might widen the dialogue a bit, and pan effects really wide to simulate distant or behind sounds while panned narrower for on-screen sounds. Stereo channels don't "have" to be panned hard left and hard right. I frequently--especially in the context of a bigger mix--pan stereo channels to narrower positions to create a "wide-mono" effect. Be creative. You're right, eventually, you have to end up with 3 discrete audio channels, but how things are distributed between those channels is up to you (and the director, and the producer, and the sound mixer, and ...)

[flextone]

So are you saying that this is a technique confined to the film sound industry? I've read posts on different forums by mix engineers and musicians.

Basically, you mean that all that LCR means is outputting three channels L/C/R but in practice each channel in each of these can be panned anywhere in the stereo field? That means that there is no such thing as LCR mixing for musical applications where the output is a single stereo file?

Now I'm really confused

[bkshepard]

True LCR requires 3 channels of audio, just like True LR (AKA Stereo) requires 2 channels. Yes you can pan the signals anywhere between the three channels just like you can between the two channels of stereo, but you ultimately end up with 3 discrete channels of audio--1 each for your three speakers. Although there are certainly good musical uses for LCR, it's main use has been in the film world, though that is being supplanted by surround formats lately.

In stereo, you put something in the center by panning it equally to both sides to create a "phantom" image between the two L/R speakers. In LCR, you literally put it in the center channel instead of splitting it between the two L/R speakers. There are a number of advantages to this, but the format isn't widely found in basic audio systems unless they have a surround system. Some systems will attempt to "decode" a stereo signal and look for sounds that can be played through a center speaker if the system has one, but for true LCR, you need three channels.

Do an Internet search for "LCR Mixing" and you'll find some good reads on the subject.

[EMRR]

Historically, as audio moved into the realm of stereo, all that was offered on stock mixers was left, center, or right via a 3 position switch. Panning was a rare luxury, and if it existed at all, you patched the "movement" source into the dedicated panning channel, if there even was one. When I hear LCR mixing, I think specifically of those three possible pan positions, with nothing in between allowed. I do not think of it as specifically related to film.

The first Altec consoles to offer LCR switching, rather than dual mono (LR or 1/2), have an internal center mixing bus that feeds a splitter, then feeds back to both L and R equally; still a 2 channel output. The next generation offered a switching matrix that allowed user selection of up to 3 output busses.