Understanding EQ

Equalization, also known as EQ, is one of the most powerful tools in mixing. If you’re learning to mix music, learning the fundamentals of EQ and how to apply it to your songs is highly beneficial. 

When applied properly, EQ can improve the sound of your tracks, make each instrument fit into the mix better, and add balance and clarity to the entire composition.

What is EQ?

You know how a song in your DAW has multiple tracks in it, each with its own volume fader to adjust the volume and find the right balance between instruments?

EQ is very similar to this, except it applies to each individual track, with the various faders corresponding to different frequencies along the frequency spectrum. Instead of modifying different track volumes in a mix, EQ adjusts the volume of different frequencies within a single track.

Volume Faders In A DAW
Figure 1: Volume faders for each track of a song
Equalization (EQ) faders in an EQ plugin
Figure 2: An EQ plugin’s volume faders for a single track. In this case, the frequency spectrum is broken up into ten “bands” of frequency. Look familiar?

The musical frequency spectrum spans from 20 Hz to 20,000 Hz, which roughly aligns with what we can hear with our ears. Different instruments generate different frequencies, which are typically focused within a limited portion of the spectrum. 

Kick drums and bass guitars primarily occupy lower frequencies, cymbals and female vocals primarily occupy the upper end of the spectrum, and guitars, synthesizers, and male vocals often fall somewhere in between. 

Frequency Response of a Kick Drum
Figure 3: Frequency spectrum of a kick drum. The horizontal axis measures frequency and the vertical axis measures the relative volume in decibels. 

Take the kick drum in Figure 3. Instead of changing the entire track’s volume with the volume fader, you might lower the kick’s volume between 200 Hz and 800 Hz to clear room for other instruments in this range or raise the kick’s volume between 50 Hz and 60 Hz to make it more punchy. 

There aren’t any rules to follow for applying EQ to a kick drum or any sound, but EQ allows you to make changes like these. 

EQ is most commonly used to remove or lower the volume of undesirable frequencies, increase the volume of desirable frequencies, and create separation and clarity between instruments that occupy similar frequencies. 

In the end, the goal of EQ is simple: to make your tracks and your overall mix sound better.

Applying EQ

If you’ve used a car stereo before, you’ve probably encountered one method of equalization: bass boost. As the name implies, this feature raises the volume level of the lower frequencies played through the stereo.

In music production, EQ allows you to do this across the entire frequency spectrum with much more precision and control. Different DAWs and plugins use different methods for adjusting these volumes, but each change is usually characterized by three settings:

  • Frequency – the center frequency who’s volume will be changed
  • Gain – the amount of volume change that will be applied in decibels (dB)
  • Q or Bandwidth – how narrow (just the selected frequency) or wide (the selected frequency and surrounding frequencies) of a section will be changed
Frequency Spectrum With EQ Adjustments Applied
Figure 4: EQ with various modifications applied

As you can see in Figure 4, the very lowest and highest frequencies have been completely removed, frequencies around 400 Hz have been lowered in volume by a few decibels, and frequencies around 2.5 kHz have been raised by a few decibels.

While many EQ plugins give you the power to see the frequency spectrum (like in Figure 4), it’s important to remember that adjusting EQ is all about what you hear, not what you see. Your goals is to make your tracks sound great. It doesn’t matter how pretty the EQ graph looks. 

EQ is best used to make small adjustments that add up across all of your tracks and busses. Most of the time, using too much EQ on a track will make it sound distorted and unnatural sounding.

Less is (usually) more, but it’s important as always to try different amounts of EQ yourself to hear what works best for each of your tracks and mixes. Every situation is unique. 

When To Use EQ

First, EQ is most effective when it is applied during the mixing process. It may be tempting to add EQ while you are recording or arranging, but you want to add EQ when you can make your decisions based on the full context of the arrangement with all of the song’s instruments in place.

Next, EQ can be applied to both individual tracks and mix busses. Applying EQ to individual tracks will give you a greater level of control over your individual tracks. Applying EQ to mix busses will allow you to shape the track at a higher level, creating subtle but sweeping changes. Try using both methods to get the best results. 

Finally, it’s important to have a purpose when using EQ. Whether you know that purpose up front or determine it with experimentation, you should know why you added EQ in every situation once it’s been added. If you don’t have a good reason to use EQ, it’s okay not to use. EQ is not required for every track, and some tracks just don’t need it.

How To Use EQ

There are endless ways to use EQ, but when you’re starting out, focus on the three most common uses for it. 

Subtractive EQ is the act of reducing or completely removing frequencies from a track. The most notable reasons for using subtractive EQ include removing frequencies associated with unwanted recording noise, reducing certain frequencies to make tracks sound better or sound different, and removing frequencies that are simply not needed. 

Additive EQ is the act of increasing the volume of certain frequencies within a track. This is typically done to improve the sound of the track, whether it be by adding more of the best sounding frequencies or changing the overall sound of the track.

Creating Separation is the process of using EQ to create space between two instruments that share certain frequencies. One common application of this strategy is when separating bass guitar and kick drum.

Creating separation can be a challenging procedure, but it usually entails lowering certain frequencies of one track, raising the same frequencies on the second track, and then doing the opposite for another section of frequencies. This allows both tracks to cut through the mix while staying out of each other’s way.

Focusing on The Numbers

You might be wondering if there are specific EQ rules for specific instruments, like boosting a certain frequency on one instrument or cutting a certain frequency on another.

While this would make equalization easier, I don’t recommend this method.

No two tracks are ever identical, no two mixes are ever identical, and as a result no two sets of EQ settings should be the same either. While one set of EQ settings might make your vocals sound better on one song, they won’t necessarily have that same effect on another.

If two tracks sound differently, why would the same EQ numbers apply to both of them in the same way? As you develop your equalization skills, it’s more important to learn the fundamentals.

Once you understand the principles, you can apply them to any instrument in any mix and generate a customized result every time. Music is an art, not an assembly line.

Should You EQ in Solo or EQ in The Mix?

When you EQ, make your decisions with your tracks in solo and as a part of the entire mix.

When isolated, it’s easier to hear you tracks’ details and hear the changes you are making with EQ. However, your end product is not a series of isolated tracks. It’s a complete song.  

Listening to how those changes affect the entire mix is most important. Your track’s EQ will often sound one way when isolated and a completely different way within the mix. Use both methods to get an understanding of what your changes are doing to each track and what will ultimately make them sound best as a part of the final song.

Developing Your Skills

EQ isn’t a tool that you can instantly master. It is a skill that needs developed over time.

As you apply EQ  to more tracks and more mixes, you will gradually become better at knowing when and where EQ is best used, hearing the differences that EQ makes when you use it, and getting the effects you want in your mix. 

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