Mid/Side EQ Processing
Mid/Side processing works by turning a stereo signal into two parts:
1. The Mid Channel containing information in both the left and right channel.
2. The Side Channel containing all the information varying between left and right channels.
So… how can you use it?
I most often use this to clean up a muddy mix, or if I need overall clarity/intelligibility. To do so, apply a low shelf filter to the sides while leaving the LF intact in the mid. Not only will this help with clarity, but help with overall imaging. This is also an important step if you plan to replicate on vinyl.
To further enhance stereo image, add a shelf filter and subtly boost the high frequencies. This will add air and space to your mix without interfering with the mid. The result will be a perceived wider and bigger mix by bringing out the stereo spread.
Aside from deploying this technique on the whole mix, I will commonly reach for this effect on drum overheads. Try boosting the sides to bring out the room sound. A boost in the mids might bring out the snare drum or toms.