EQ for beginners: small changes, big difference

An equalizer (EQ) turns parts of the frequency range up or down. Think of the bass and treble knobs on an old stereo, but with more control over where and how much.

There are two kinds. A graphic EQ has a row of sliders at fixed frequencies, usually somewhere between 5 and 10. A parametric EQ lets you choose each filter's frequency, gain and width yourself. Parametric is more precise. Graphic is quicker to understand.

A tip that doesn't seal costs you more bass than any EQ setting will give back. If an IEM sounds thin, try another tip size first, per ear. Only when the fit is right does it make sense to correct the sound, otherwise you're adjusting for a leak that changes every time you put the IEMs in.

Every IEM with a measurement on our site shows its curve next to the Harman IE 2019 target, the dashed line. Where the coloured line sits above the target, that part sounds louder than most listeners prefer in research. Below it, softer. That gives you a starting point that isn't guesswork.

• Start with the biggest, widest difference. On the EDX Pro that's the bass: on average 4 dB above target from 20 to 250 Hz.
• Then look for narrow peaks that might sound sharp, like the one around 7.8 kHz (4.6 dB above target).
• Leave dips around 3 kHz alone at first. Most IEMs we have a measurement for sit below the target there on these rigs, and boosting that range quickly sounds shouty.
• Ignore everything above about 8 kHz. Measurement rigs disagree too much up there, and how deep the IEM sits in your ear changes it too.

Two filters, both cuts. You'd set them up in a parametric EQ like this:

1. Add the low shelf first and listen for a few songs you know well.
2. Bass still too heavy? Go to -5 dB. Too thin now? Go back to -3 dB.
3. Add the peak filter only if S and T sounds bother you. If they don't, skip it.
4. Toggle the EQ on and off at the same volume to check that you actually prefer it.

Only have a graphic EQ? Lower the sliders up to about 250 Hz by 3 to 4 dB and leave the rest flat. On an iPhone with Apple Music, the Bass Reducer preset is a quick way to try the same idea.

The opposite case is the TinHiFi T2. It measures 6.6 dB under the target in the bass on average, and more than 8 dB under below 60 Hz. If you want a bit more weight, you have to boost.

A low shelf of +5 dB at 120 Hz with Q 0.7 brings the T2's bass average from -6.6 to -3.0 dB vs target. Don't try to fill the whole gap. Small drivers have limits, and a big boost in the deep bass is where distortion starts.

Rules of thumb that keep it clean:

• Cut rather than boost where you can.
• Change one thing at a time, in steps of 1 or 2 dB.
• Compare at the same loudness. Louder almost always sounds better for a few seconds, which fools everyone.
• Fewer filters is better. Two or three is enough for most IEMs.

• Android: Wavelet. Works on the sound of most music apps and can load ready-made corrections from the AutoEq project for many models. Free, with extra features you can pay for.
• iPhone: the Music app has EQ presets in the iPhone settings, including Bass Reducer and Treble Reducer. They only work in Apple Music, and you can't make your own curve.
• Spotify: has its own equalizer in the playback settings. On some Android phones the button opens the phone's own equalizer instead.
• Windows: Equalizer APO with Peace as the interface. Free, works for the whole system and handles parametric filters, so you can type in the values from the table above.
• Mac: eqMac. A system-wide equalizer with a free version.

AutoEq itself is an open-source project that calculates EQ settings from published measurements. It's useful as a second opinion. Just remember it corrects towards a target, and the target isn't necessarily your taste.

Some USB-C dongles have an EQ built in. The FiiO JIEZI A and B have a 10-band parametric EQ and the SnowSky Tiny A and B a 10-band EQ, all set in the FiiO Control app or on FiiO's web page. The iBasso DC04 Ultra has EQ settings on its own screen, without an app.