September 20


EQing A Control Room — Time vs. Amplitude

By Keith Livingston

September 20, 2016

acoustics, amplitude, EQ, home recording

Recording engineers often EQ a control room, or mixing environment. The idea is that a room will emphasize certain frequencies. A room that’s 20 feet wide, matches the wavelength of about a 55Hz tone (a very low sound). The room is going to emphasize that tone, and tones that are multiples of that frequency.

The walls of a normal room are parallel, if they’re 20 feet apart, they’re 20 feet apart the entire length of the room. And that’s why recording studios try to avoid parallel surfaces. They don’t want any frequency to be emphasized. It can fool the ears. You might think you have a rocking kick drum sound, and when you get it out and listen in a room that doesn’t have a 55 Hz boost, it sounds weak.

So, audio folks sometimes use an equalizer to de-emphasize the frequencies that the control room emphasizes. All fixed, right? Well, no. Here’s why.

Here’s Why ‘Tuning The Room’ Doesn’t Work

Room resonance is a time problem, and EQing provides an amplitude solution.

Here’s what I mean. When a room resonates at a particular frequency, it means that the frequency lasts longer. The room rings a bit longer at that pitch. When you EQ that frequency out (by decreasing the frequency on an equalizer), you decrease the amplitude (level) of the offending frequency, but it still rings longer than other frequencies.

So, EQing your control room (which is likely to be in your spare bedroom, and also your tracking  room), is only a partial solution.

Better Solutions

If you can, modify your room a little bit to break up any resonant frequencies. Blankets, furniture, bass traps, and stuff on the walls can all be used to advantage, to subtly shape a room.

Beyond that, I have a radical thought for you in terms of tuning your mixing environment to sound good.


Don’t do it. You know how, if you walk into a room where they just cooked eggs, you can smell the eggs, then ten minutes later, you no longer smell them? You adjust to your environment.

Your ears will adjust, too. Have a bunch of reference tracks in different genres that sound really great, and listen to them in your mix room. Tell your brain, “This is what ‘great’ sounds like in this room.” Listen back to those tracks sometimes when you’re tracking and frequently when you’re mixing.

Don’t introduce a bunch of EQ that doesn’t actually solve the problem.


PS: If your tracking room (the room you record in) resonates, and you can’t modify the room, use more close micing techniques.

Keith Livingston

About the author

Keith Livingston started recording his own music in the late '70s, on a 4-track. He worked his way into live sound and studio work as an engineer -- mixing in arenas, working on projects in many major studios as a producer/engineer, and working in conjunction with an independent label.

He taught audio engineering at the Art Institute of Seattle, from 1990-1993, and in '96, contributing to authoring several college-level courses there.

He was General Manager of Радио один (Radio 1) in St. Petersburg, Russia.

Now he spends his time recording his own songs wherever he roams, and teaching others to do the same.

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