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!
This month we’re digging deep into Equalization.
To kick off EQ month, we’re starting with this primer on all things EQ: what it is, how it works and when to use it.
What Is EQ in Music?
EQ (aka 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:
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. Shelving EQs: High Pass and Low Pass Filters
A shelving EQ boosts or cuts frequencies above or below a specific threshold.
There are two types: High Pass filter and a Low Pass filter.
High-Pass Filter (also called Low-Cut Filter): Lets through all the frequencies above the set threshold and cuts 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
Low-Pass Filter (also called High-Cut Filter): Lets through all the frequencies below the set threshold and cuts 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 EQs
Graphic EQs typically have multiple sliders. Each slider has a fixed frequency band. Graphic EQs have between 7 and 31 bands.
Graphic EQs are usually used on 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 EQs
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 (20-20kHz).
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.
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).
This control lets you pick which frequency you will affect with your EQ.
This control lets you choose the volume of your EQ setting in Decibels (dB). It usually goes from -15dB to +15dB.
‘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 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!
Next chapter: make a good mix great with a frequency infographic and EQ guide!