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Equalization 101 – Everything Musicians Need to Know About EQ

By Leticia Trandafir

This article originally appeared on The LANDR blog.

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Good EQ is vital to a great mix. EQ is one of the key tools for producers when mixing audio — along with volume, panning, and compression.

But a lot of people overuse EQ without knowing what it really does to their sound. We want to help you become an EQ pro, so let’s dig deep into equalization. Here’s a primer on what it is, how it works, and when to use it.

What Is EQ in Music?

Equalization is the cutting or boosting of a particular frequency (or range of frequencies) in the frequency spectrum. An equalizer (EQ) divides that spectrum into sections (called “bands”) that you use to cut or boost parts of your sound.

Humans can hear audio frequencies roughly between 20 and 20,000 Hz. Any sound that human ears perceive sits somewhere in that frequency spectrum.

Here’s how the frequency spectrum usually gets divided:

Fundamental Frequencies

Sounds (instruments, natural sounds, voices, etc.) are rarely pure — except for synthesized sine waves. What gives sounds their recognizable timbre is a mix of their fundamental frequency and their harmonics.

The fundamental frequency is the main frequency — the one you hear as the “note” of a sound. It’s also the loudest. The extra frequencies that add character to the sound are its harmonics. You don’t hear them as separate notes, and they’re not as loud.

This is an important concept to understand when it comes to EQing your own mixes. It means that most sounds are made up of information across a broad spectrum of frequencies — not just their fundamentals.

So a sound with a high-frequency fundamental will also have information in the lower spectrum. EQing with this in mind is crucial for getting your best possible mix.

What Does EQing Do to Your Sound?

EQing doesn’t create new frequencies. Think of EQing as sculpting: You’re working with your raw material — the existing frequencies of your sound.

By cutting or boosting certain frequencies, the EQ shapes the tone and character of your sound. EQing also changes the balance between the frequencies that are already there. This gives you the power to carve out space in the frequency spectrum for each of your sounds to get them sitting right in the mix. Simply put, EQing is a pillar of good mixing.

When to Use EQ: Corrective and Creative Approaches

There are two equally useful approaches to EQing:

  • Corrective EQing
  • Creative EQing

Corrective EQing lets you remove undesirable elements from a recording — like a hiss or floor vibrations. But beware: Overusing EQ for corrections ends up sounding unnatural and distorted. Always aim to have your best recording before EQing.

Untreated rooms make specific frequencies resonate in an unpleasant way. Microphones pick up the resonance and cause feedback. Corrective EQs are a great solution for eliminating feedback in your mix — they allow cutting that specific resonant frequency out.

Creative EQing lets you:

  • Make individual instruments sit better in your mix
  • Accentuate good elements of a sound by boosting them
  • Creating a sense of distance (near or further elements in the mix)
  • Make a sound thinner or thicker

Types of EQs

The main differences between different EQs are:

  • How they split up the frequency range
  • How much precision they allow you

The more “bands” there are on your EQ, the more precise control you have on what you boost or cut.

Here are some party-conversation starters for you: the three main types of EQs! Just kidding — knowing them will make you a better producer, though:

1. High-Pass and Low-Pass Filters

A High-pass filter (also called low-cut filter) lets through all the frequencies above the set threshold and attenuates the ones below it.

Use it to:

  • Reduce unnecessary deep bass that is taking up space in the lows
  • Reduce the rumble caused by floor vibrations in a recording

A Low-pass filter (also called high-cut filter) lets through all the frequencies below the set threshold and attenuates the ones above it.

Use it to:

  • Reduce hiss in the high frequencies
  • Take the edge off of a sharp and high sound
  • Remove unnecessary highs from your bassier sounds to get more room in the high end

When you combine a high-pass and a low-pass filter, you get a band-pass filter — which lets through a particular band and cuts what is both below and above.

A band pass allows you to hone in on specific frequencies to boost or cut. High-pass and low-pass filters are more general, while a band pass is often used for more specific tweaks.

2. Graphic EQ

Graphic EQs typically have multiple sliders. Each slider has a fixed frequency band. Graphic EQs have between seven and 31 bands.

Graphic EQs are usually used in the overall mix to make it sound good in a particular room. Here’s a Hot Tip from Presonus:

“If you are mixing in a ‘dead’ room, you may want to boost high frequencies and roll off some of the lows. If you are mixing in a ‘live’ room, you might need to lower the high-midrange and highest frequencies.”

It’s not as common to see a graphic EQ on an individual track. For that, you would use parametric EQs.

3. Parametric and Semi-Parametric EQ

For optimal control and versatility, this is the type of EQ you’re looking for.

A parametric EQ gives you full control. It lets you choose the main frequency to EQ, the gain, and the bandwidth — or Q for short (more on this below).

Parametric EQs come with three to seven (sometimes more) bands. Most parametric EQs use points that you plot by dragging them across the frequency spectrum to the exact frequency you want to adjust. Vertically, you have the decibel axis (loudness), and horizontally, you have your frequency spectrum axis (20-20 kHz).

Use parametric EQs on individual tracks to sculpt your sounds.

Semi-parametric EQs are the same as parametric, except that the Q is fixed. There’s less to adjust so they might be simpler to use. You’ll often see them on analog mixers.

+ Read more on Flypaper: “14 of the Most Commonly Confused Terms in Music and Audio”

Basic Controls on an EQ

Let’s look closer at the basic controls of an EQ. Most EQs have all of the following settings (except for the Q, found mostly on parametric EQs).

Frequency

This control lets you pick which frequency you will affect with your EQ.

Gain

This control lets you choose the volume of your EQ setting in decibels (dB). It usually goes from -15 dB to +15 dB.

“Q” or Bandwidth

The Q is the width of the EQ.

A higher number will give you a tight Q (like I and II in the NOVA above). A tight Q sounds best for cuts. Use it to surgically remove a precise frequency. A tight Q doesn’t sound natural for a boost. Our brain isn’t used to hearing precise frequencies boosted in that way.

A lower number will give you a wide or open Q — it will affect the frequencies around your main one (see III and IV on the NOVA). This is what you want to use for a boost. It sounds smoother and more organic to our ears.

Equalization Nation

Equalization is a key part of audio creation. Now that you know the basics of EQing, you have everything you need to start experimenting with your own sound.

Mixing is the art of fitting all the audio puzzle pieces together. Making them fit relies on key processes like EQ.

Know what your EQ does to your sound. Choose the right EQ for each job. With some practice, you’ll be a bonafide mixing wizard!

Whether you’re laying down demosorchestrating digital strings in your DAW, or sampling found sounds in a beat, getting a good mix on your track could mean the difference between failure and fame. Sign up here to be notified when Soundfly’s new course on modern mixing techniques goes live! 

Leticia Trandafir

Leticia Trandafir is a DJ and music maker with a love for 303 basslines. Writer and Community Manager at LANDR.

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