How to EQ a Room

August 23, 2017 by Ben Stowe, CTS

It seems that I may have been in a select few that watched the adventures of Robert McCall (Edward Woodward) as he solved problems for people in the Equalizer. I was slightly vindicated when Denzel Washington picked up the character in the 2014 motion picture release of the same name and the rest of the world finally heard of it. For some reason, whenever I hear the term equalizer, even in an audio context, I think of that show.

In essence, that’s what our audio equalizers do for us. They solve problems. Specifically, they address frequencies that might be building up in a room, or lacking in our system, etc. There are several types of EQs, but more often than not for main system tuning we are using a graphic EQ. These typically have a number of faders (15, 31, etc) at set frequencies and filter widths (1/3 octave is typical) and these faders can be physical, or represented digitally. The functionality is the same. When we raise that fader we are adding more of that frequency, and when we lower it we are reducing it.

When selecting what you should raise or lower there really isn’t a right or wrong answer as sound is somewhat subjective, but most can agree on an offending frequency. Those are the first places I like to go. I like to find the frequencies that are building up and creating pain points in my sound and reduce them. In order to do this we should use program material that is well known to us. A nearly failsafe way to do this is to use pink noise and a real-time analyzer. This will identify frequencies and their amplitudes. We can identify any that are a bit higher and bring them down.

While pink noise is scientifically excellent for the purpose, we don’t dance to it, so I also encourage you to listen to some well known program material. Songs that you know well, and ones that have specific characteristics that you are looking for in your overall sound. Then you can adjust the EQ further to adjust the sound to your liking. It’s definitely a good idea to train your ears a bit to identify frequencies (there are apps out there now that can assist in training you). For most events I no longer use pink noise, I will just tune using music as I’m fairly comfortable identifying what I’m looking for.

A few nerdy nuggets for you here to finish us off. Most inexpensive EQs are not linear phase EQs, that is to say that when you make an adjustment to the EQ you slow that frequency down slightly, and this can cause some phase issues. Therefore we want to balance the amount of changes we are making. Drastic EQ changes are probably an indicator of something more serious that should be addressed in the system. Little changes lead to little mistakes, big changes lead to big mistakes.

Lastly, my favorite button on the EQ is the bypass button. Push it in to defeat the EQ and see if it sounds better or worse. That’s a good way to see if you’re headed in the right direction until you are confident in tuning a system.

Oh, and rumor has it that Equalizer 2 is coming out in 2018. See you at the theater.

Ben Stowe, CTS Ben Stowe, CTS (18 Posts)

Ben’s love of electronics and technology led to years of schooling in Electricity, Electronics, Robotics and Lasers. Ben supported himself through school by building and selling strobe lights and other electronic devices. He built his first DJ show largely from scratch and scrap, often repairing broken items others had thrown away because he could not afford to buy new equipment. He holds a Minnesota electrical license, and his AV installs have been featured in almost every major industry trade magazine. His relentless passion for education has led to a number of other certifications and accreditations, including the most widely recognized one in the AV industry, the InfoComm CTS. His love for education inspired him to begin the ProAcademy educational sessions, focused on increasing understanding of AV technologies within the industry. Ben has been involved in a number of technical writings, lectures, presentations, as well as research and development assistance with a number of manufacturers for products, industry wide. He is also a regular contributing author to industry magazines in the United States and Europe. Ben’s presentations have been featured across the world both as a part of industry leading trade shows, and as a presenter for various groups and functions. Some of these events include BPM in the United Kingdom, Mobile Beat, the ADJA National Convention, Wedding MBA, and a national tour as a headlining presenter for an industry magazine. The United States Armed Forces branches have also called upon Ben to provide engineering and training assistance. His highly informational, slightly nerdy and always funny presentation style have made him a favorite at events, while his sincere desire to help people with their application of technology have made him a favorite with them after the event. Ben serves the industry as the President of NLFX Professional, an industry leading supplier of sound, lighting and video systems, a role he has maintained since founding the company in 1993.

Filed Under: Sound