All the types of eq explained

Hello everyone and welcome to this week's article!

Today we're going to deep dive in a subject already touched in our main equalization article, but explaining more the differences between the various types of equalization and which one to use according to the needs.

- Shelving eq and Filter eq: those are the simplest of all, and can be either with an analog interface (with knobs) or with some graphic representation, but they all recreate the fact that you can choose an eq shape (in this case a filter or a shelf), choose the frequency range where to put it and dial in how many dB to add or subtract to that area (if you are filtering, obviously you're bringing to zero db the sound from a certain point up or down). By concept, for shelf we mean that for example from a certain area (for example 1khz) up (or down) we will start adding or removing gain, and this usually happens with a not too steep curve, to not make the change too unnatural.

- Graphic eq: this is a way to intervene in the frequency areas with more precision, and also this type of eq comes from the analog world. Initially the spectrum was split in just few areas, like 4, then they started adding more and more faders to the units up to 30 bands or more. You can intervene with the individual bands (the more the number of faders, the smaller the frequency range for each band), and the models with more bands obviously allow much more surgical correction, to the point that the most precise ones are used mostly for room correction, meaning to clean up specific resonance areas of a sound. When you have plugin recreation of those old units, usually they try also to recreate the way they used to colour the sound, for example adding some harmonic content or some saturation.

- Parametric eq: the way those equalizer works is an evolution of the shelving ones, basically they work the same way but they let you choose among more shapes (for example a bell shape), decide the Q (which is the width of the shape) and add usually many of those shapes, also making them interact-overlap among each other (this is a specific more of the digital ones, like the Fabfilter pro Q). This type of eq allows much more control and by consequence also much more possibility to make mistakes, but it's one of the few that for example allows you to make a wide boost in a frequency area and then, in that same area create several very narrow cuts to tame the resonances.
The most feature-rich digital ones allows also to make corrections only in the part of the sound panned in the middle or only to the one on the sides (MID-SIDE eq) or to affect only one of the 2 sides of the stereo field.

- Dynamic eq: this is much closer to a multiband compressor than to an equalization, meaning that it's dependent on the level of the input. With a dynamic eq you can for example choose an eq bell and decide to reduce the gain on a certain area: the gain reduction in that area will be higher when the gain is higher in that specific area and vice versa. This is used to tame certain frequencies that spike only every now and then like the sibilant consonants in a vocal track.

Note that all these types of eq mentioned are "archetypes", but in the reality of today, especially in the digital domain, you will find equalizers which offers a combination of those functions (for example there can be an eq which can also offer dynamic eq functions, or a graphic eq which offers also a frequency analyzer and mid-side features, and so on).

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