Equalisation is used widely throughout the music industry. They are most commonly used to alter or manipulate the frequency response of a sound recording in order to improve it’s comfortability in the mix. They can also be used to flatten sound systems in order to optimise the volume levels. EQs are one of the most important tools in a mix engineers arsenal and to be as good as I can possibly be at mixing I should become acquainted with the type of EQ and the best way of using each. There are four main types of EQ; Shelving EQs Graphic EQ, Parametric EQ and semi-parametric EQ. Below are the described functionalities of each.
This type of eq is the most simple and inexpensive, can be found in any common equipment such as a stereo or Hi-Fi equipment. It offers the possibility to control the bass and treble, sometimes it also has a mid control. You can increase or decrease the gain and the central frequency and bandwidth are fixed, this type of equaliser is less commonly used in professional audio but can be a simple way to control EQ. This type of EQ in my experienced is most commonly observed on guitar amplifiers. Shelving EQ’s are extreme and therefore not suited to subtle use.
Graphic EQ’s consist of banded frequencies each with an individual gain control allowing the engineer precise control. However the flexibility of these modules can be problematic as the targeted frequencies are set in stone. They’re different types of graphic equalizers, the most common is the octave graphic equalizer, which has 10 frequency controls. This is pretty consistent because the audible bandwidth runs 10 octaves that are 30 Hz, 60 Hz, 125 Hz, 250 Hz, 500 Hz, 1 KHz, 2 KHz, 4 KHz, 8 KHz, 16 KHz. And it is in those frequencies where we can increase or decrease the intensity of the audio signal. The H-EQ by waves offers a much wider range of frequencies: Known as 32 band EQ.
Parametric EQs are the most precise and versatile of the range of equalisers available to us. These EQ’s can contain many filters each with fully adjustable parameters of frequency, gain and bandwidth making it the most dexterous and precise type of EQ we can use. Parametric EQs are the most common type of EQ in the music industry and are very good at making corrective changes as well and creative.
This equalizer is similar to the parametric EQ in the sense that it allows you to select the frequency you want to equalie and the gain.However, it differs from the parametric EQ because you can not change the allocated bandwidth. This type of EQ is commonly seen on mixing desk.
To be an adept mix engineer, I will have to familiarise myself with all of the circumstances for which to use each EQ and develop my own work flows with each. It is also worth mention to say that some hardware equaliser’s circuitry colour the sound. This is known as an EQ not being transparent and dependent upon its application this can be a benefit or a detriment.
Information sourced from: https://www.masteringbox.com/types-of-eq/