EQ for beginners: how to stop your sounds stepping on each other

I'm sure it's happened to you. You finish a track at home, play it back and think it's the best thing you've ever made. Then you play it on another system and your heart sinks: the bass you worked so hard on doesn't show up, the kick sounds like a cardboard box, the hi-hat is grating and the instruments step on each other. It happened to me. I wasn't short of ideas: I was short of the technical knowledge to support them.

Welcome to an unmixed, or badly mixed, track. The good news is that mixing can be as much fun as composing. And the first tool you need to master is EQ.

Why sounds step on each other

Human hearing covers roughly 20 Hz to 20 kHz; the upper limit drops with age and varies from person to person. All your sounds share that same space. When the kick, 808, piano and vocal all have lots of energy in the same zone, they compete, and the result is muddy — what I call "hearing cats meowing".

Every sound has a fundamental frequency, which defines its note or pitch, plus a series of harmonics that give it its colour and character. Harmonics are how we tell a piano from a guitar playing the same note. Many sounds also carry resonances or noise that add nothing to the mix.

The idea behind EQ

EQ is deciding which part of each sound's spectrum you want to keep and which is surplus: find the essential, clean out the excess and make room for everything else. For that you need a parametric EQ, where you choose each band's frequency, gain and width (the "Q"). A graphic EQ, with fixed bands, is much less precise for this job.

Finding the key frequency: the sweep

Turn your monitors or headphones down first: you're about to make a big boost.
Create a bell band with a very narrow Q and raise it a lot.
Move slowly through the spectrum, from low to high, listening. Work with your ears, not your eyes.
When the sound "jumps out" and becomes more obvious — on a kick, for example, its body or its attack — you've found an important zone. If what jumps out is an annoying resonance, that's where to cut.
Bring the band back to a sensible gain: the sweep is for finding, not for leaving it there.

As a reference, a kick's body usually lives in the low range (roughly 35 to 350 Hz depending on the sound); above that it's mostly attack and character. But every sound is different: that's why you listen.

The filters and bands you'll use

High-pass: lets the highs through and removes the lows below the frequency you set. Bring it up from the bottom until the sound starts losing body, then back off a little. Ideal for cleaning unneeded low end from vocals, pianos or hi-hats.
Low-pass: the opposite. Lets the lows through and removes the highs above the chosen frequency.
Band-pass: combines both and leaves only a band. Very useful as an effect (telephone or radio voice).
Shelf: gently raises or lowers everything above or below a point.
Notch: a very narrow band to "erase" one specific frequency, such as a hum or resonance.
Dynamic EQ: a band that only acts when that zone goes over a certain level. As if an EQ and a compressor had a kid.

A filter is like a club bouncer: it decides what gets in and what doesn't. With a high-pass, the lows stay at the door.

Tips to get started

EQ in context. A sound can seem perfect soloed and not fit the rest. What matters is how it sounds in the mix.
Cut before you boost. Removing what bothers you usually gives a clearer result than boosting what you want.
Compare at matched loudness. If the EQ raises the level, it will always seem better. Match the level when you bypass it.
Less is more. Don't touch what doesn't need it: I explain it in less is more.

Once the frequency balance is clean, the next step is controlling dynamics: see compressor types. And for placing each sound left and right, the stereo field.