I recently talked about mid side compression and how you can use it to correct issues on different levels of a mix or master, or even create some interesting aesthetic effects. Mid side EQ is another effect which exclusively targets one or the other, so let’s talk about what is mid side EQ and when you might use it.
What is Mid Side EQ
Mid side EQ is a form of EQ which allows you to specifically target the center or one or both sides of your audio.
A plugin like my favorite, FabFilter’s Pro-Q allows you to designate any EQ band as being mid or sides (or one specific side, left or right) only. I put together a complete FabFilter Pro-Q 3 review to see why it gets my recommendation for the first plugin I recommend anyone who is doing their own mixing get:
After you create a band, that specific band’s controls appear below it. Amongst the typical EQ settings you can adjust, the default “Stereo” setting can be clicked to bring up a menu with your five options.
Selecting the exact channel you want to EQ will allow you to exclusively cut or boost that frequency in that specific channel whether that’s left, right, both (side), the center, or the entire stereo width which is default.
As an aside and a bonus, you can also click on the scissors to basically duplicate the settings of that band.
This is useful when you want to simultaneously cut on one of these channels while boosting in another all at the same frequency range:
Above I’ve shown three adjustments at 450Hz a track; a 3dB boost on the left channel, a small boost in the center, and a 4dB or so cut on the right. This is referred to as split EQ within the plugin and is for truly surgical, rolling up the sleeves adjustments. For what it’s worth, you can do this up to 24 times (the max number of bands you can have in one instance of the plugin).
But getting back to what is mid side EQ, let’s move on to when you might want to EQ a specific area of your audio.
There are multiple practical applications for using mid side EQ, beginning with the aforementioned mastering stage.
Low End Cleanup Across Mix
When you’ve got a completed mix which is a bit of a mess on the sides and sounding cluttered, an easy fix in mastering is to apply mid side EQ on the sides exclusively and high pass filter around 100Hz.
This centers the lowest low end of your mix, simultaneously cleaning up a lot of mud while prioritizing those sub-100Hz frequencies for the kick and bass which are in the center of the mix 99% of the time anyway.
As I covered in my low end mixing guide, this is one of the keys to getting a cleaner mix.
Mid side EQ is an extremely useful tool whenever you’re limited to the audio you have and don’t have the option of addressing it on a mix meaning track level.
It’s worth mentioning that it’s obviously still also useful on a track level when you’ve got a stereo track with issues baked into it in one particular area.
Propped Up Vocals
Another useful application is prioritizing space for another essential ingredient in your mix in the lead vocal.
Just like the low end elements, your lead vocal should be centered 99% of the time (unless you’re doing a one-off aesthetic effect or panning your double tracked vocals wide).
Analyzing the frequencies in the instrumental of your mix, you can see which tracks are heavy in some of the same frequencies the vocals thrive on, like the 150-300Hz body range or the 3-5kHz presence range.
When simply panning those tracks out of the way isn’t an option, you can apply some cuts in the mid channel of those instruments.
Even better is you can sidechain EQ those center (channel) bands in the aforementioned frequency ranges to your vocal so that they attenuate those frequencies exclusively when the lead vocal is playing in the mix.
As an aside, sidechaining the center frequencies of any stereo track in your mix to something else can create interesting results when used effectively, but I digress.
The effect of the sidechain EQ on conflicting frequency tracks which generally need to be panned center creates the space for the vocal but not without cutting more than necessary, specifically only carving out those aforementioned frequencies for when your vocal needs it and leaving those conflicting instrumental tracks untouched otherwise.
Carved Out Mud
I mentioned cleaning up low end mud earlier; you can also carve out a lot of your mix’s mud from the sides in the 300-600Hz range.
This shifts the emphasis on the sides to the upper mids and high frequencies, simultaneously creating a nice contrast to keep the overtones of the body more to the center.
You can do this in the mastering phase or even just drop a mid side EQ on your mix bus in the mix and solo those sides to get some ideas of where that mud is stacking up there so you can clean it up on a track level.
All of this said, mid side EQ isn’t typically necessary and if done aggressively it can actually send your stereo audio out of phase, so keep that in mind and keep your adjustments relatively light, especially the higher up a level you’re applying that mid side EQ to (like on the mix bus or on a master).
