You’ve probably seen the ubiquitous “1/3-octave EQ”. (This would be the piece of equipment in the audio rack with all the little sliders on the front.)

Unfortunately it will likely have all sliders set the same: A - smiley face; B - frowney face.

Both settings happen largely due either to the inexperience of the operator or a poorly designed sound system.

Or both.

First let’s look at the 1/3-octave equalizer and get an idea of how it can best be used.

Note the photo of the 1/3-octave equalizer below, and notice the 31 sliders on the front panel. Each slider is set on a frequency.

Starting at the left slider, and moving right, the frequencies begin at 20 Hz and end at 20 kHz.

Look at the first slider (20 Hz) and count over to the right to the third slider, and you will find 40 Hz.

This is one octave higher in frequency than 20 Hz. What that means is there are three sliders/ filters per each octave, meaning that each filter is 1/3-octave apart from the filter next to it.

With this information (and what we discussed in my previous article) about where certain important frequencies are, we can better EQ our system.

1/3-octave graphic equalizer

For example, we know that the range for vocalists is about 70 Hz for the lowest bass singer to about 1400 Hz for the highest soprano, so setting a smiley face on the 1/3-octave EQ does nothing more than boost all frequencies on either end of the vocalist range - or in essence - cuts all the frequencies where the vocals should be!

Next time you can’t hear vocals in the house mix (or vocalists complain that they can’t hear themselves in the monitors), check to see if your EQ is smiling at you.

It’s always my recommendation that the main house EQ, if being done with a 1/3-octave EQ, never be randomly adjusted.

If your system was installed by a competent audio contractor; EQ should already be set for maximum performance and shouldn’t need to be changed.

Any changes you believe necessary for improvement should be done on the EQ section of your console.

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