Overview
What sets parametric EQ apart from your standard 3-band DJ EQ or even a graphic equaliser? Mostly it’s the ability to make very precise and deliberate adjustments in ways that other types of EQ can’t. When discussing Parametric EQ in this piece, we’re referring to an Equaliser that is made up of one or more Parametric filters, whose Frequency, Gain, and Q can be controlled. This is probably best explained by comparing Parametric to Graphic equalisation. Graphic EQ is most often seen as a set of sliders, each representing a fixed frequency range (band/bandwidth) which you can boost or cut. The more sliders, the narrower the bands and the more detailed control you have over the frequency spectrum.
However, parametric EQ allows you to choose the centre frequency and adjust the bandwidth to your own liking. Being able to accurately select the frequency you wish to adjust and how much those adjustments affect the surrounding frequencies is why parametric EQ is often referred to as “surgical”. The precision with which you can “carve” up a piece of audio is a major attraction to those who want to control, in detail, the overall sonic spectrum of their production.
So how does it all work? To understand how parametric EQ achieves such precise results, let’s look at some of the most commonly used parameters.