EQ

EQ, meaning equalisation, is “the balancing of the amplitude of different frequencies within a sound to alter the treble, mid and bass.” This page covers types of EQ graphs, types of filters and their uses, and parameters that can be applied to these EQ filters.

Specification 👇

Component 1 Specification

Component 2 Specification

Component 3 Specification

Component 4 Specification

EQ Graph Types

There are two types of EQ graph; parametric EQ and graphic EQ. They both do the same thing but display the frequencies in slightly different ways.

Above is a parametric EQ graph, which depicts various filters applied in different colours.

This is a graphic EQ graph with the same frequencies being cut/boosted as the other graph, but this display uses sliders set at various points along the frequency spectrum to change the amplitude of the frequencies, rather than filters.

EQ Filter Types and Uses

Filters include pass/cut filters, shelf filters, bell filters and notch filters.

Low pass / High cut filter

A low pass or high cut filer allows the low frequencies to pass, or be heard, and rolls off high frequencies. It is a useful filter for reducing sibilance, as sibilant sounds are in the higher regions of the frequency spectrum.

High pass / Low cut filter

Pretty much the opposite of a low pass or high cut filer. It allows the high frequencies to pass and rolls off low frequencies. It is used for reducing low frequency rumble that might be present in a recording.

Bandpass

A bandpass filter allows mid frequencies to pass but rolls off the high and low frequencies. It can be used to isolate a specific range of frequencies and used to cut extreme high and low frequencies.

High Shelf

A high shelf can cut or boost frequencies above a certain threshold. This filter is for controlling high end frequencies.

Low Shelf

A low shelf filter is used to cut or boost frequencies below a certain threshold. Used for controlling lower end bass frequencies.

Bell Filter

A bell filter boosts or attenuates frequencies around a specified central frequency point. Due to high Q-value (see below for more on this), this filter is best suited for boosting or attenuating relatively large ranges of frequencies.

Notch / Band Stop Filters

A notch filter or band stop filter cuts a range of frequencies around a specified point while low and high frequencies pass on either side of the frequency range. This kind of filter is used to cut very specific frequencies (Q value always high). Especially useful for cutting out unwanted resonances.

EQ Parameters


  • Gain: determines how much you boost or attenuate a frequency/range of frequencies. Measured in dB.

  • Cut Off Frequency: the point at which the filter is applied. Measured in Hz.

  • Q: the width of a bell and/or notch filter. The higher the Q value, the narrower the width of the filter.

  • Slope: Used to control the harshness of the roll off on a high/low pass filter. Measured in dB/octave. The higher the dB/octave number, the harsher the slope.