How to Set an Equalizer: What Each Frequency Does

Overview

An equalizer changes how loud different parts of the frequency range are. That is the whole idea. Every slider in an EQ owns one slice of the spectrum, and moving it up or down makes that slice louder or quieter relative to everything else. What makes an equalizer hard to learn is not the concept, it is the labels: a screen of numbers from 60 Hz to 15 kHz says nothing about what any of them will do to the song you are listening to.

This guide maps those numbers onto what you actually hear, so you can go from a complaint like "not enough bass" or "the vocals are buried" to a set of equalizer settings you can enter anywhere. For example, "the vocals are buried" is a cut at 400 Hz far more than it is a boost anywhere. The EQ generator on this site loads that shape for you, and the guide below explains why it is the shape. It also covers the one way EQ can make things measurably worse, which is running out of headroom.

Why it matters

Most people meet an equalizer twice: once in a list of named EQ presets like Rock, Jazz and Bass Booster, and once as the custom screen of a graphic equalizer, full of sliders, which they close again. The named presets are opaque, because nobody tells you what Rock actually did. The custom screen, meanwhile, offers no way in at all. So the equalizer gets left alone, and a pair of headphones that are too bright or a podcast where the voice sits too far back stay that way.

Knowing four or five landmarks on the spectrum is enough to fix most of that. It is a small amount of knowledge with a large payoff, and unlike most audio advice you can verify it in about ten seconds by moving one slider and listening. Therefore the useful thing is not an EQ frequency chart to memorise, but a habit: change one band, listen, keep it or undo it.

How EQ bands work

Each band has a centre frequency and a gain in decibels. Set the 60 Hz band to +5 dB and the energy near 60 Hz gets roughly five decibels louder, tapering off as you move away from that centre. Nothing is added that was not there: an equalizer can only amplify or attenuate what the recording already contains, which is why boosting 15 kHz on a recording with nothing up there changes very little.

Decibels are logarithmic, so the numbers are smaller than they look. For example, 3 dB is a clearly audible change, 6 dB is a large one, and 10 dB or more is dramatic enough to sound like an effect rather than a correction. Most useful settings live between plus and minus 6 dB.

The bands are spaced logarithmically too, which is why they go 60, 150, 400, 1000 and not in even steps. Each one covers roughly the same musical distance as the last, about an octave and a third, and that matches how hearing works: the gap between 60 Hz and 120 Hz sounds like the same size of step as the gap between 6 kHz and 12 kHz.

What each frequency band does

Five landmarks cover the range, and together they are the only EQ frequency chart worth keeping in your head. These are tendencies, not rules, because the same boost lands differently on different recordings and different headphones.

• 20 to 100 Hz, bass. Weight and physical impact. Kick drums and bass instruments carry important energy here. What does 60 Hz do? It controls the bottom of that range, the part you feel as much as hear. Small speakers and cheap earbuds cannot reproduce it at all, however, so the same boost is inaudible on a laptop and overwhelming over headphones.
• 100 to 500 Hz, body. Fullness and warmth. This is where too much becomes thick or muddy, and a small cut around 150 to 400 Hz is the standard fix for a mix that feels congested. It is also the band that surprises people: when music sounds unclear, the problem is more likely an excess down here than a shortage up top.
• 500 Hz to 2 kHz, mids. Where most instruments and the core of a voice live. Cutting the mids is the shape behind the classic smile curve. It sounds exciting at first and pushes vocals into the background, which is the opposite of what most people want from a podcast or an audiobook.
• 2 to 6 kHz, presence. Forwardness and articulation. What frequency makes vocals clearer? Mostly this range, so 2.4 kHz is where EQ settings for vocals start. It is also the first area to turn harsh, because consonants and cymbals get sharp here, so keep boosts modest.
• 8 to 15 kHz, air. Sparkle and the impression of detail. How much of it you hear depends heavily on your headphones and on your own hearing, which loses the top of this range gradually with age. A lift here can add polish, and it can also bring out sibilance the recording already had.

Turning a goal into settings

Start from the complaint, not from the sliders. For example, "it sounds muddy" and "it needs more bass" point at opposite ends of the same region and want opposite moves. Here are four common goals and the shapes that address them, all of which you can load as EQ presets and then adjust:

• How to make bass deeper with EQ. A bass boost EQ is three moves, not one. For example: 60 Hz up 6 dB, 150 Hz up 3 dB so the low end does not sound hollow, and 400 Hz down 1 dB. The cut is what makes the extra bass read as depth rather than mud, and it is the step people skip.
• How to make vocals clearer with EQ. Lift 2.4 kHz by 2 to 3 dB, and cut 150 Hz and 400 Hz by a similar amount. Half the job is getting the instruments out of the way, which is why cutting works better here than boosting alone.
• How to reduce harshness with EQ. Cut 6 kHz by 3 to 4 dB and 2.4 kHz by 2 to 3 dB. This is the one goal that needs no boosts at all, so it costs nothing in headroom and cannot cause distortion.
• Fixing a muddy sound. Cut 150 Hz and 400 Hz by 2 to 3 dB and leave the bass band alone. Adding more bass to fix muddiness is the most common wrong turn, because muddiness usually lives above the bass rather than in it.

In every case, make one change, listen to a track you know well, and only then make the next one. Two changes at once and you cannot tell which one helped. Once a curve is working, the tool copies it as text, as a link, or as an image, so you can send the exact settings to somebody else rather than describing them.

Boosts, clipping and the preamp

Can EQ cause distortion? Boosting can, and this is the one way an equalizer makes things objectively worse rather than differently. Most music is mastered close to the maximum level a digital file can hold. Boost a band by 6 dB and the loudest moments in that band now want to be louder than the format allows, so they get flattened at the ceiling. You hear crackle, grit, or a hard edge on the loudest parts, and it gets blamed on the headphones.

Every equalizer that offers boosts also offers the fix, normally a preamp or gain control on the same screen. Lower it by the size of your largest boost. For example, a curve with a +6 dB peak wants a preamp of -6 dB. The balance you designed is unchanged, because everything moves down together, and you make up the difference with the volume control. The tool shows this number alongside your settings and speaks up when a curve is boosted far enough to be worth acting on.

If your player has no preamp, the alternative is to build the same balance out of cuts. Rather than raising the bass by 6 dB, lower everything else by 6 dB and turn the volume up. The result sounds the same and cannot clip.

Applying settings in your own player

A web page cannot reach into Spotify, your phone's system equalizer or a pair of headphones, so the settings have to be entered by hand. Open your player's equalizer, choose the custom or manual preset rather than one of its named ones, set each band, then set the preamp if there is one and save.

Your equaliser will probably not have these exact seven bands. For example, a five band EQ offers 60 Hz, 230 Hz, 910 Hz, 4 kHz and 14 kHz, so 150 Hz and 400 Hz here both feed its 230 Hz slider; a ten band one has room for all seven values and gaps to fill in between. Match the nearest frequency you have, and where one of your sliders sits between two of these values, split the difference. The shape of the curve carries almost all of the effect, and being a hundred hertz off on a band centre is not something you will hear.

Common mistakes

• Boosting everything. Raising every band is the same as turning the volume up, only with less headroom. An equalizer works on differences between bands.
• Chasing a best setting. There is no universally correct curve. The recording, the headphones, the room and your own hearing all change the result, so a preset is a starting point.
• Adding bass to fix muddiness. Muddiness lives between 150 and 400 Hz. Adding weight below it makes the problem larger.
• Ignoring the preamp. A big boost with no preamp cut is the main cause of distortion that appears right after somebody discovers the equalizer.
• Judging in the first five seconds. Louder tends to sound better immediately, and a boost is louder. Listen to a full track before deciding.

Private by design

The tool runs entirely in your browser. Nothing is uploaded, no microphone or audio permission is requested, and no account is involved. Your settings are kept in your browser's own storage so the page remembers them, and when you copy a link the seven values travel inside the link itself. For example, a link ending ?eq=6_3_-1_0_0_0_1 is the whole preset, which is why you can read it in the address bar before sending it. The share image is drawn in the same way, from the settings on screen, so sending a friend the exact EQ settings you landed on costs nothing and reveals nothing else.