Stereo referencing
Once armed with a capable M/S tool, spend time analysing the width of well-produced reference tracks you like. Load a stereo file of a song (ideally in lossless WAV or AIFF format) in your DAW. Use your M/S utility plugin to solo the track’s mono signal, then the side signal, listening carefully as you do so. After that, go back to the full stereo mix and decipher the relationship between them. As mentioned, anything stereo in the mix will disappear when you solo the mono component, and that mid signal is what will be heard when the track is played through a mono speaker setup.
Using our M/S ‘isolator’ plugin to flick back and forth between a commercial track’s mid and side signals, we can judge which mix elements have been panned or widened. How does this affect the mono mix, and also the full stereo mix? For example, you’ll probably notice the floaty tail of a vocal reverb or a synth’s out-of-phase stereo content in the tracks’ side signal. Do the stereo elements get quieter or disappear in the mono sum? Get familiar with how a ‘good’ mono mix sounds in relation to the stereo mix.
The best commercial releases will have all sorts of stereo tricks going on. Individual elements will be panned apart by varying amounts. Synths may feature multiple unison voices spread out to the sides of the mix. Guitars, pads and vocals may have been treated with modulation effects such as chorusing, phasing and flanging. Pseudo-widening plugins could have been used to inject centred signals with ‘false’ stereo content. And, of course, there’ll likely be virtual ambience (aka reverb) and stereo delay repeats in there somewhere.
Now that you have a better idea of how a mix is made up, it’s time to monitor your mix. Pop your M/S utility plugin on your project’s master bus, then repeat the monitoring process. Keep in mind your mental reference point of a ‘good’ stereo mix in relation to its equivalent mono mix. Do this regularly as you write and mix a track to get a grip on your stereo effects.