Mid side. When? What? Your approach(es)

So, let me explain it this way.. You have a midi arrangement with a guitar panned 80 / 80 both sides but you use the exact same guitar synth. Change one of the L or R tracks to something else and the differences start to expand the stereo field without artificial enhancement which can come to bite you. I can go into the technical but just try it..

So when we start to manipulate L/R with EQ or compression we create variations, just like double tracking two different guitars and amps L / R which will most likely have different EQ. The same pretty much applies to anything including synths and anything that's not sort of dead center. However with a piano or synth of one it's going to be relatively equal therefore it can sound a bit muddled or homogenised, that's where we'd generally use mid side to spice things up.

In short and still in a non technical way, variety is the spice of life and it can make a huge difference to recordings if one manipulates the mid / side even if you're not doing LCR. Let's not talk about things like unmatched dual mono compression though because that may unbalance things and not in a good way.

My late friend Chris Garges was pretty heavy into Mid-Side tracking and processing. It's a bit of a mystery to me still, but I have liked using it for tracking rooms on occasion. In processing, I bought a Bereich03 BAX EQ and I'll literally just switch each band between mid, stereo, and side and see what it does to the mix. I've been surprised a few times thinking "I want to spread the highs out to the side" and then decided it didn't add, it subtracted.

Using the Pulsar W495 on overheads on a few things made the drums feel more open.

Yeah, when you get in the car and think WTH?!

Mid-side can drastically improve the stereo image of a mix when done right. I've never "mucked things up," at least not how I would describe it. But I do agree you can vastly change how something sounds and run into phase issues if it's too drastic.

Basically, all the audio that is stereo is side, and all the mono information is mid. So, it's super useful on stereo busses, tightening up a stereo image, or chiseling a little bit of the side signal, keeping all the information in the mono section clean.

For example, find a synth or guitar part too muddy? Maybe instead of adding an EQ or dynamic EQ to the entire track, pull out some of that low end information from the sides, that way you don't lose that tight punch in the middle. Or maybe the opposite, you want to pull some mud out from the mid section to make room for a vocal to sit, but leave that weight on the sides. I do mid-side EQ a lot, and find it amazing for really tightening up tracks in general.  

I also love mid/side compression, so think about it this way - you are only compressing the stereo section of the track, but keeping the mono section completely uncompressed (or vice versa). It's a very lovely form of parellel compression, and I do it almost every track (that has drums at least).

There's mix applications, but here's a vid that shows one way to mid-side in recording, using a ShinyBox mic (I used to make) for mid-side. Took me a bit to dig it up. Shows how he uses it on acoustic:

First umm it’s MONO / SIDE not mid!
It can worked absolutely wonderfully, but you have to understand that M/S is all about phase, in a general world of close mic’ed multitracked quasi mono stereo most of sound field is about level and phase relationships. Any level and phase changes can really effect the soundstage, all dynamics control is level changes and almost all EQ and filters are going to introduce change in phase.
You have to be really careful with M/S and even more careful with any mix changes after some M/ S has been used.

I'm just gonna say mid/side completely changed the game for me when I fully conceptualized it. Of course, it takes some time to understand when to use and when not to. And you can stick your head in the sand and try to ignore it all you want, but at the end of the day, it has the potential for amazing use cases once fully recognized. I've also used that free goodhertz mid/side plugin, simple but comes in very handy sometimes.

Just because someone else uses it doesn’t make it so, why I do believe Neumann, AKG, Schoeps, Fostex,Sony and numerous AES papers on the subject pre date the Existence of Izotope Danny.

Buzz Audio SOC 20 allows you to compress stereo signals as left/right or mid/side with the flip of a switch: pretty cool way to bring out the room, etc.

This clip actually motivated me to buy SOC 20 vs. the other Buzz Audio opto offerings:

If they are petty enough to use a universally known phrase against me then I don't really want to speak to them in the first place. Fortunately 99.9% of them aren't and they return my messages very quickly too. Common courtesy works wonders in most situations, not everyone has to or needs to read AES papers.