Equalizer guide: what each frequency does and how to use it well

Human hearing picks up, at best, sounds between 20 Hz and 20,000 Hz. Each instrument and voice occupies zones of that range, and when several overlap, the mix sounds muddled. Equalizing is sharing out the space: removing what's surplus in each sound so the important parts come through. Used well, an equalizer fixes more problems than almost any other effect.

A map of the spectrum

Graphic or parametric

A traditional graphic equalizer has fixed bands, and you only decide how much each goes up or down. A parametric one also lets you move each band's frequency and its width, called Q. A high Q acts on a very narrow slice and is for fixing problems, like a whistle or a resonance. A low Q covers a wide range and is for adding color.

Our equalizer has eight parametric bands you drag on the curve while watching your audio's spectrum, with six filter types: high-pass, low shelf, peak, notch, high shelf and low-pass. It also includes four channel equalizers inspired by classic consoles to add character in a few moves.

Five rules that work

1. Cut before you boost. If a voice sounds dull, try removing low mids before raising the highs. The result is cleaner and doesn't get close to clipping.
2. Small changes. 2 to 4 dB is usually enough. If you need more than 8 dB, the problem is probably in the recording.
3. Compare with bypass. Turn the EQ off every so often. When you boost something, the ear tends to think it sounds better just because it's louder.
4. Hunt problems with a narrow peak. Boost one band a lot with a high Q, sweep it slowly until the flaw sounds exaggerated, then cut at that spot.
5. Listen in several places. Headphones, laptop speaker and phone: what sounds right on all of them is well equalized.

Starting settings

Voice and podcasts

• High-pass at 80–100 Hz: removes rumble, desk bumps and traffic noise without touching the voice.
• Gentle cut at 250–400 Hz if it sounds boxy or 'roomy'.
• Light lift between 2 and 5 kHz for presence and intelligibility.
• If the esses hiss, cut a narrow band between 5 and 8 kHz.

Music for listening

• More punch: a gentle peak between 60 and 100 Hz. For much more, use Bass Boost.
• More sparkle: a high shelf from 8–10 kHz, without overdoing it.
• Less mud: a wide cut around 300 Hz clears up thick mixes.

Small speakers and phones

Small speakers don't reproduce bass below about 150 Hz. Boosting it only makes them rattle or distort. It's better to cut below 100–120 Hz and add some presence in the mids, which is what those speakers can actually deliver.

Common mistakes

• The exaggerated 'smile': boosting lows and highs a lot and scooping the mids impresses for a minute, but it's tiring and buries vocals.
• Equalizing in solo: a sound can seem thin in isolation and perfect in the mix. Judge in context.
• Using it to fix noise: an equalizer won't remove broadband background noise; that's what the noise remover is for.

The filters, one line each

• High-pass: lets through what's above a frequency and removes what's below. Ideal for removing rumble.
• Low-pass: the opposite. Removes highs above a point; useful for an 'old radio' effect or to tame hiss.
• Shelf: raises or lowers everything below (lows) or above (highs) a point, like tilting a scale.
• Peak: raises or lowers a zone around a frequency, with the width set by the Q.
• Notch: a very narrow, deep cut to remove one specific tone, like a whistle or a hum.

Check your own hearing

With age we stop hearing the highest frequencies: many adults perceive nothing above 14–16 kHz. If you're going to equalize the highs, it helps to know how far your hearing reaches. The hearing test plays tones from 20 Hz to 20 kHz so you can check in a couple of minutes.