Studio 101 – Equalizers

Last month, we began our year-long look at audio processors and the signal chain with a look at preamps. This month, we will examine one of the most used processors—EQ. An EQ (short for Equalizer) is a frequency-dependent amplifier that allows for both boosting and cutting the level of a specific range of frequencies (within the range of human hearing, 20 Hz–20 kHz).

In simple terms, though, EQ is a tone control.

An EQ unit typically consists of one or more bands designed to boost or cut a particular frequency range. Adjusting the level of a specific range of frequencies changes the balance of the harmonics and overtones in the audio, altering the overall tone. In the recording world, this can be done on a track-by-track basis or a whole song to make the final mix the best it can be—often described by words like warmer, clearer, rounder, brighter, darker, etc. Today, EQs come as both hardware units and plugin software.