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How to equalize: Fine-tune your listening experience

Cut narrow, boost wide
July 26, 2021

Before a song makes it onto your playlist, it will have been mastered to optimize playback across as many devices as possible. Audio engineers know how to equalize (EQ), so the music will sound just fine in most scenarios. While not all playback systems are ideal, if you know what you’re doing, you can make your music shine on your gear with a few simple tweaks.

Why should you EQ your music if a professional engineer has already done it? Well, there are two main reasons why you’d want to equalize your music, and they’re not mutually exclusive.

  1. Preferences determine if you want to EQ at all, and how you want to go about doing it. Everyone hears things a little differently, because of the physiology of the human ear. This can also encompass loudness preferences and expectations. What sounds good for most people could sound even better to you, if you know what to do. And we all know you’re the only person that truly matters, right?
  2. The playback system also dictates what merits an “optimal” EQ curve. Nothing is perfect, and you might find your headphones or speakers have a hardware quirk to them that doesn’t sound right. If it’s not too serious, then chances are you can account for that quirk when you EQ. It’ll be like it was never even there.

Editor’s note: this article was updated on July 26, 2021, to add techncial information and a contents menu.

What is an EQ?

The Razer Hammerhead True Wireless Android app open on a Samsung Galaxy S10e smartphone next to the Razer Hammerhead True Wireless Pro earbuds.
Some earphones feature companion apps that let you create a custom EQ setting.

Before we get into the gritty details, it’s probably best to go over what an EQ is. EQ is an abbreviation of equalizer (or equalization) and is generally defined as “the process of adjusting the relative levels of the different frequency bands of an audio signal.” An EQ that aims to replicate audio accurately requires you to adjust the different frequencies so that they all come out at the same level (or perceived loudness level).

On a practical level, if you’ve ever been around audio equipment of any kind, you at least know what an EQ looks like. Most people will recognize the bass or treble knobs on the car radio. Those are basic EQ controls. They get a little more advanced once you dip your toe into more advanced consumer electronics and recording equipment. By adjusting these sliders or turning these knobs, you can control the output of a given frequency range, letting you tweak the sound coming from your equipment.

What should you know about EQs?

Now that we know what an EQ is, we can start getting into the fun stuff: how to EQ. There are two parts to an EQ: center frequency and bandwidth. Center frequency might sound complex, but it’s just selecting the specific frequency that you want to adjust. Bandwidth, also known as Q (for quality), refers to how narrow the selection is for the adjustments that you want to make. If you go into a car and see the bass and treble knobs, those usually have a very low (broad) Q, which looks like a small hill when you’re adjusting it. But if you want to target a very specific frequency range, then having a higher (more narrow) Q will let you achieve this. Visually, this will look more like a spire than a hill.

A screenshot with labeled wide and narrow Q.
On the left: a wide Q adjustment. The right: narrow Q.

Is there a technique to creating a custom EQ?

There are two ways to tweak your sound when learning how to EQ. The first is to make the target frequency louder by raising the level (amplitude) of a specific range. This is called boosting. It makes sense if you think about it, you’re just boosting the output of something that you want to hear more of. On the flip side, you can also decrease the output of a specific frequency range for something that you want to hear less of. This is called cutting.

Cutting is usually a better approach than boosting

As a general rule of thumb (actually it’s more like a rule), cutting is better than boosting. If you boost too much you can introduce distortion, which defeats the object of what we’re trying to accomplish here.  In short, it’s better to cut the frequencies that you want less of than boosting the ones you want to hear more of. Done correctly, this will give you the same result while keeping everything below the distortion threshold.

What if the new EQ curve sounds weird?

Trust your ear: sound is a very personal experience. And we mean that both physically and psychologically. Moral of the story is that things sound different to each person, so everything from here on out, regarding how to EQ, is just a guideline to help find what works best for you.

What are the important frequency ranges for EQ creation?

Whether you want more bass or less cymbals, you should know more or less where their frequency ranges lie. The chart obviously doesn’t include every sound effect and instrument ever made, but it’s a good generalization.

A chart showing where common music notes reside in the range of audible frequencies.
Most fundamental notes for common instruments lie below 4kHz.

Notice how almost all of the instruments lie under around 10kHz, save for cymbals and hi-hats which can go a bit higher. Sub-bass is usually considered to be between 20- 80Hz, and though it’s hard to hear: you’ll physically be able to feel the air being pushed if you have a large enough woofer. Then there’s the kick drum and bass guitar fundamentals that mostly reside between 60-250Hz.

The fundamental frequencies of guitars and both male and female vocals (with obvious differences) can be found roughly between 80-1,000Hz. One area that you should pay special attention to is the range between 250-1,000Hz. As you can see there is a lot going on in that region (and we only showed a few examples). If you indelicately add too much emphasis here, it can result in what some refer to as a “muddy” sound, cut too much and it might start sounding “hollow.”

Make Dr. Dre proud.

Adding emphasis around 2kHz usually makes the attack of picked guitar strings easier to hear. Amplifying the 8-16 kHz range makes it easier to hear overtones and upper harmonics, something our brains perceive as clarity. Obviously the reverse applies as well, and bumping anything in the 20-250 Hz range gives you a low-end thump that would make Dr. Dre proud.

If you want to test how good your hearing is, we generated a few sine waves down here. Humans can technically hear anywhere from 20Hz-20 kHz, so we made four that span the entire range (20Hz, 250Hz, 2kHz, 16kHz).

What undesireable frequencies should you be aware of?

Rather than looking for the parts of a track that you like and then boosting them up, find the parts of the track that bother your ears. Then, cut them down. Usually, you can do this with a high Q (narrow), and sweep through until you find a noise that’s particularly harsh or conflicts with something else that you want to have more prominence. Then, you can lower the Q and cut that part out.

This gets rid of the unsavory aspects of your music without introducing noise and distortion, something that often happens with heavy-handed boosting. When you’re done, you can raise the overall master volume up to a pleasing volume and still have a natural-sounding mix.

Get rid of the extreme highs (add a low-pass filter)

A demonstration of a low-pass filter.
A low pass filter preserves everything below a set limit, and cuts everything above it.

Some audiophiles will tell you that they need headphones that can reproduce sounds well above 20kHz, which is questionable. Humans can only hear up to 20kHz, and unless your audiophile friend is part-dolphin, they can’t hear a  thing that goes above that frequency. Want proof? Just download any dog whistle app and see how far up you can push it and still hear the tone.

Get rid of the extreme lows (add a high-pass filter)

A chart showing a high pass filter.
A high pass filter preserves the sound above a certain cutoff, attenuates everything below it.

Just like how there’s no point to having anything above 20kHz, it’s really hard to hear anything below a certain point as well, especially over speakers if you don’t have a fire sub-woofer and some bass traps. So just cut your EQ curve at around 50Hz; this is called adding a high-pass filter.

Should you use EQ presets?

Some apps/software come with built-in presets, which can be a helpful starting point when learning how to EQ. EQ presets exist for a reason and are generally made by professionals. A good place to start is by selecting your favorite preset and then making minor tweaks from there. It’s easier than starting from scratch but still gets you a tailored sound profile.

Some apps, like Neutralizer for Android, make it super personal by letting you do a hearing test beforehand to see which frequencies matter the most to your ears. For desktop, there’s also Voicemeeter by VB-Audio or Equalizer APO. There’s nothing wrong with using a preset! If you want to dig deeper, beyond just learning how to EQ, keep these tips in mind and you’ll be fine.