Billy86
I'm afraid I don't understand the routing in a DIY scenario and I'm unclear on the phase issue, overall. I'm going to try a Waves Hybrid EQ that supports M/S processing with control over phase. How do you I approach that? Thanks so much.

it's actually fairly simple these days as many plugins (WAVES, FabFilter, etc.) do that for you i.e. the decode your stereo signal into mid/side components (M-S), do the processing and convert back to stereo, all within the plugin itself i.e. you simply insert the plugin and click the M-S button and now instead of EQing left and right, you EQ center vs sides.
 
I do this very often to clear out the center where most of the overlaps happen (e.g. wide pads that should be wide and not mask anything in the center, I carefully EQ M-S style) ... but the same applies for side-chained compression where you could e.g. bring down the M part of the guitar whenever the vocals kick in while keeping the sides untouched.

Idk. It is tricky. Maybe I'm not creative enough in my thinking.

A stereo track is basically two mono tracks. When you raise the volume of one, phase inverted, in the other and vice versa, you will quiet the material that is shared between the tracks. The phase inverted material could be eq'd first.

I believe, but don't know, that this is what you are doing when you cut center mids during the vocal. This means that non centered mids from the other track probably show up, phase inverted in the same number of dB as the cut.

It is goofy. Maybe there is a better way to do this math. I'm probably underestimating the good people at cakewalk.

I'm suspicious of magic. I shouldn't be. There really are little wizard boys running around saving the world.

And spreading some phase inverted material between the channels can sound kinda cool.

It would be awesome if there was a center track, and a left and a right and that's how EQ was applied.

If I'm missing the way to sum two tracks to end up with only the center material, I'd love to learn how. Anyone?

"A stereo track" is not a pair of mono tracks. Stereo is in a sense greater than the sum of its parts.

You can out a pair of mono tracks together all day long and won't end up with a stereo image.

If a take a mono guitar track and place it L and take another guitar track and place it R that does not a stereo track make.

But a pair of mono tracks however can be used to capture a stereo image e.g. from a stereo microphone or a pair of microphones (in a stereo configuration) or even a stereo synth output. A la the way Pro Tools does it. This can be useful because you can then pan each mono track (or L and R) to any position.
 
Stereo tracks though (or interleaved) are still easier to handle for most signals like this because you are only dealing with one thing as opposed to two.
 
Mid Side processing is interesting and useful if you want to treat the Mid and Sides component as separate identities and then after converting back to stereo it is possible to affect the centre or the outside (extreme L and R) sounds differently.
 
It saved my butt once in mastering. I was given a stereo recording a piano in a hall and it was just too roomy. Piano sounded too far away. After converting to M and S and turning the S component right down most of that room sound disappeared and the piano sounded much closer. Amazing in fact. Even through the end result was mono by applying some slight reverb of a much smaller room it was possible to massage it into a pretty decent result overall. i.e. a close piano sound with just a hint of room behind it. And that reverb was just enough to add some slight stereo imaging back into the close sound too.
 
M/S recording too is very cool. e.g. using a M/S configuration to make a stereo recording of an acoustic sound. The ability to manipulate the stereo width after the fact can sometimes be very useful indeed.

Thank you everyone! I'm going to see what I can do with M/S. Pretty cool to explore.