The question was recently asked, “ How do you know when you should boost or cut with an equalizer?”
This is a great question but before we can answer it we first need to understand what an equalizer does and why you would need to use one.
WHAT IS AN EQUALIZER?
By definition an equalizer is a tool used to adjust the tone or frequency response of an audio system to achieve the desired sound quality.
Basically every note that is being played by any instrument has a frequency equivalent. So this means that a middle C for example is the same frequency wether it is played on a piano or a violin. Now this can cause some issues within your mix if you have too many instruments playing the same frequencies as there is only room for one in that space without it effecting another. I wrote an article on how to fix clashing frequencies which you can take a look at if you want more information on this subject. Click HERE
An equalizer comes in many different forms. There are graphic equalizers, parametric equalizers, freeform equalizers and linear phase equalizers. Within these categories are FIR equalizers, FFT equalizers and IIR equalizers, just to name a few. Bottom line is that there are many, many different equalizers and many, many different brands of equalizers out there to chose from. Since the goal of this article is more about when to use an equalizers on a signal and not about the different equalizers themselves, I won't go into great detail here.
Parametric equalizers are very flexible and a great tool for boosting or cutting frequencies. So for the sake of this article when we talk about an EQ or equalization we will be referring to this type of equalizer.
SO WHAT DO WE KNOW?
So as we learned earlier an equalizer can be used to change a tone or a frequency response to a signal. We also know that each note has a frequency or an energy, so equalization is basically an increase or a decrease of a signals strength at that audio frequency. By using a equalizer with a tight “Q” you can really focus on the specific frequency that you want to work with.
SO WHEN DO YOU CUT AND WHEN DO YOU BOOST?
Well there is no blanket answer for this question because it greatly depends upon the sound you are dealing with and what you are trying to achieve. Plus, as I have said before there are very few rules when it comes to mixing audio. Once you have confidence in your earring then it is always best to trust your ears first and foremost. But generally speaking if you are trying to get rid of a unwanted frequency then you will want to use your equalizer to cut it. If you find a frequency that needs to stand out in your mix a little more then of course you will want to boost that signal with your EQ.
The reason that a parametric EQ is great for this task is because it allows you to sweep for the offending frequencies. Sweeping is simply moving the knob on your equalizer up and down the frequency spectrum until you find the frequency that you are looking for. One of the easiest ways to achieve this is to open a parametric EQ, choose a frequency, overly boost that frequency and then move the knob up and down the spectrum until you find the offending one. With this method it is very easy to hear the signal in question. Once you have found it then you can either bring the boost down to a reasonable level or you can bring it down even further and start notching out the signal if you are trying to cut the frequency.
The key here is to never do anything in your mixing just because or because it is something that you always do. The question of when to cut or when to boost with your equalizer may seem like a simple one to some of us, but if you only apply effects within your mixes for specific reasons then you should make better choices and the result is better mixes overall.
Stay tuned for more weekly tips and tutorials every Wednesday.
Article written by Alex Butler
Alex is an audio engineer, studio producer and freelance writer based out of Seattle, WA.