What is mid/side EQ (and how to use it)
Normal EQ treats left and right together. Mid/side EQ instead splits the signal into the mid (what's common to both channels - your centred kick, bass and lead vocal) and the side (the stereo difference - the width, room and spread), and lets you EQ each on its own.
Updated 2026-07-07Mid and side, explained
The mid is the mono sum: everything panned centre lives here - kick, snare, bass, lead vocal. The side is the stereo difference: reverb, wide synths, doubled guitars, room. Split them and you can, for example, roll the lows out of the sides (keeping bass mono and punchy) while lifting air only on the sides (widening the top without smearing the centre).
What mid/side EQ lets you do
It's a width and clarity tool. Because you're editing the centre and the edges separately, you can solve problems a normal EQ can't touch without collateral damage.
- High-pass the sides (~100-150 Hz) so the low end stays mono and translates on club systems.
- Add air (a gentle high shelf) to the sides only, for width without a harsher centre.
- Tame a harsh or boxy centre without dulling the stereo image.
- Lift presence on the mid to push a vocal forward while leaving the width alone.
Watch mono compatibility
Boosting the sides heavily can sound huge in stereo and thin when the mix folds to mono (phones, club subs, some Bluetooth speakers). Check your mix in mono after any big side move, and keep the low end in the mid - sub energy in the sides is the fastest way to a mix that falls apart in mono.
Work in mid/side with AURORA - free
AURORA runs in Stereo, Mid-Side or Left-Right, and the analyzer splits to match - mid in white, side in violet. Place any band on M, S, L or R and widen, tighten and clean with total control. Free.
What does mid/side EQ do?
It splits the stereo signal into the mono centre (mid) and the stereo difference (side) and lets you EQ each independently - so you can widen the sides, tighten the centre, or keep the low end mono without affecting the rest.
When should I use mid/side EQ?
Mostly on buses and the master: to widen a mix (air on the sides), to keep bass mono and punchy (high-pass the sides), or to fix a harsh centre without narrowing the image. It's usually overkill on a single track.
Does mid/side EQ affect mono compatibility?
It can. Big side boosts can vanish or thin out in mono. Always check in mono after side moves, and keep sub-bass in the mid so it stays solid on mono systems.