No, what I mean is a tad different…more complex.
I know the traditional m/s tools. I’ve just tested “voxeng msed”, and probably it is similliar to the melda plugin, it also sports “side mute” and “mid mute” buttons. But this is very simple stuff, you can do this with renoise, with gainers, stereo expanders and some send channels, too, I’ve even once tried applying the tradition m/s stuff this way. The “mid” channel will contain “l+r” and also sidepanned stuff from both sides, and the “side” channel will be “l-r” or “r-l”, and as a stereo channel (I think this will make each channel contain the inverse of the other) sound very weird and twisted with headphones (expecially bass), chronically out of phase so to say. A bit like the renoise stereo tools with maximum width which will sound odd with bass and headphones, too, but more extreme.
The thing is these stereo tools will put the intermediate signals out of phase. They can be reconstructed back to the original, but once you manipulate them in strong ways, the final result might be partially or completely out of phase, similliar to the “side” channel as percieved in stereo mode by the plugins mentioned above. This is because both components need to be there to make the original, if you cancel things out of one part but not the other the reconstruction will overshoot and put stuff together in a wrong way.
The center channel extraction stuff on the other hand won’t simply substract the channels from each other, but correllate frequencies, trying to find shared and individual components. This will enable to make up a channel that will contain only stuff from the middle of the stereo field (and not like in the m/s way with the sides just added up) and also pure l or r side signals, i.e. a stereo signal that will contain only action from panned to the left or right sounds, or wide reverb tails but then only the wide stuff, and not the centered components. So different to m/s. Spooky, isn’t it? But I believe this could be a real nice way to craft stereo signals, and drive for example side eqing or the like to new dimensions. Put back together there won’t be artefacts, so you can drive any effects you like on mid and side, be them destructive as you wish, no phase issues in the final result. Even the l/r side signal might be used directly without phasing, given the original source was unproblematic.
As for phase issues with tracks, I’m already used to placing a mono-mixer on the master channel. Right next to that hp filter to see how it will sound with weak bass speakers. For every stereo action I now and then check up a mono mix to see if it destroyed something badly, or if the music is still recognisable and pleasant. It is a lot of trial and error. I think this stereo out of phase stuff is also relevant not only for mono speakers, but also for arbitrarily placed stereo speakers. Maybe if mono will cancel too much, in stereo speakers might fight each other, too, and make weird effects depending on the listener’s position. Like it is maybe a bad idea to put width on sub/bass frequencies, they better be either mono or simple panned.
Huh, yeah, and the example does sound like a m/s style width button has been used. I hate this - I alway try to use other effects for stereo width. You can feel the pain when using headphones, I literally get sick from the asymetric out of phaseness of bass/mid frequencies. You did some good. I could achieve similliar effect by using the msed, splitting the signal with it, and applying a tiny delay to one channel of the side signal, then summing back together. The out of phase instrument in the background could be heard clearly again in the mono sum, just like in your summed example. But there was some very slight comb effect that was apparent for me with my own trick when I a/b ed my chains. Couldn’t judge whether you did the same trick, your wav also was a bit louder than the original or my attempt on it.
There could be a lot of information in S in regards to frequency and character that we would want to preserve in mono. I believe there ought to be a better way, where the “message” and “meaning” (our auditory interpretation) of the signal is preserved better.