How mid/side processing works
The middle and the sides of a stereo file are two different signals, and most of the trouble people have with width comes from treating them as one. These are the explanations I'd give someone sitting next to me.
What it is
The ideas, before you touch a control.
What is mid/side processing?
uses MS WidenerMid/side splits a stereo file into what both speakers share and what only one of them plays, so you can treat the centre and the edges of a mix separately.
Mid/side compression, explained
uses MS CompressorA stereo compressor lets the loudest thing in the mix decide what happens to everything else. Splitting the detector between mid and side stops that.
Mid/side clipping explained
uses MS ClipperClipping the mid and the side separately is a different operation from clipping left and right, even with identical settings. Here's why, and what to set.
Mid/side transient shaping, explained
uses MS PunchA transient shaper changes how a hit starts and how long it rings. Split into mid and side, the centre can hit harder while the room gets shorter.
Where it goes
What to do at one particular point in a mix.
Mid/side saturation for vocals
uses MS SaturatorSaturating a whole vocal bus hits the lead and the doubles alike. Drive the side separately and the lead stays clean while everything around it opens up.
Mid/side on the mix bus
uses MS SaturatorWhat's worth doing to the middle and the sides of a full mix, in what order, and the mistakes that only show up after the master is done.
Multiband compression on the mix bus
uses MS MultiCompA full-band compressor lets the kick decide what happens to the vocal. Splitting it into bands fixes that, and adding mid/side fixes what bands alone can't.
Stereo width in mastering: how much is too much
uses MS FieldWidth is the easiest thing to overdo in a master, because more of it always sounds better in the moment. Here's how to tell useful width from borrowed level.
How to do it
The steps for one specific job.
How to widen a mix without losing the bass
uses MS WidenerMost stereo wideners thin out the low end, because widening moves energy out of the centre where the bass lives. A crossover fixes it.
How to use mid/side EQ
EQ in stereo moves the centre and the edges of a mix together. Splitting a band into mid and side is how you brighten the room without brightening the vocal.
How to check mono compatibility
uses MS FieldA mix that folds badly to mono loses level where you spent the longest. What causes it, how to find the band responsible, and how to read a correlation meter.
How to make bass mono, and when not to
uses MS WidenerSumming the low end to the centre fixes most mono-fold problems in one move. It costs you something too, and the crossover point is where that trade is made.