Pultec and the other Parametric Equalizers: a guide with Free Vst Plugins

Hello everyone and welcome to this week's article!
Today we will say something about the history of Equalization, in a way similar to the one we did for Compression.

An equalizer, as we have already seen, is a tool that allows us to boost or cut a certain frequency area. In the case of a Graphic equalizer you have the frequency range divided in "slices" and you can raise or lower the single band, and this system is used usually for the whole track.

A parametric equalizer instead lets you decide with one knob the frequency area to cut or boost, with another knob the amount of db to add or subtract, and with a last knob how narrow the cut or boost should be.

This kind of eq is used both for mixing the single tracks, and for mastering.

The story of equalization starts around 1920, and it was made mainly to process the voice of a radio host; equalizers were initially tube driven, then, the more mainstream they became, the more the analog version became popular, to the point that around 60s and 70s every mixing console had a separate analog parametric eq section for each track. 

Around the '90s the rack eq became back popular, and today we can choose among tube driven, analog and digital eq, in passive (so just made to filter out frequences) or active version.

All this different versions in the market are made to produce different results: a tube eq will give to the mix a certain amount of harmonic enhancement,  an analog eq will have a certain sonic property that can be heard in almost every record of the 70s (a very subtle saturation and a certain eq cut), while a digital eq has the undeniable advatage to let us sometimes see graphically (with a spectrum analizer).

The spectrum analizer has been a revolutionary tool: it lets you see the actual wave and to operate surgically in the specific frequences with great precision, letting you using not only your ears, but also your eyes.

Today we have Vst emulations of all kinds of hardware eq, and especially lately we are starting to see again the arrival in the market (both free and paid) of vintage parametric equalizers, with pieces of software that tries to recreate not only the way those processors used to work, but also the collateral properties, as the saturation, for example.

Usually  parametric equalizers have one gain knob that at unity position leaves the signal unaltered, and if you turn it up or down it adds or subtracts dbs in the assigned frequency area, but there is a very particular hardware processor, called Pultec EQP-1A that works differently (see picture above).

This equalizer, lauched originally in 1951, is one of the most used of all times in the music industry, and its latest incarnation is still on sale today.

The original Pultec is a tube eq which has the particularity to have for each one of the 2 bands, 2 gain knob: one for the amount of boost to apply and one for the amount of attenuation.
Said this way it sounds like those two knobs cancels out each other, but the truth is that the two knobs which works in the same frequency range doesn't actually affect exactly the same identical frequences: the attenuation in facts happens in a slighly higher area than the boost, and this makes possible to achieve an attenuation that has for example a boost in the area before the slope starts.
Is it also possible to control the Q, which is how narrow is the boost or cut.

Why to choose today a Vst that emulates an old piece of hardware with very limited controls like the Pultec instead of using a very flexible new Vst equalizer, with a lot of functions and a built in spectrum analizer?
Because often, if the programmers are good, it recreates the coloring that this device used to give to the tracks, and because it forces you also to use softer settings, which leads to less drastic and surgical changes in the sound, leaving a more natural result which is proper of the '60s and '70s records.
My suggestion is to give it a shot and decide with your ears.


Here's 2 versions, one free and one paid of the Pultec EQP-1A Vst emulations:

Ik Multimedia Vintage Equalizer (paid)

Ignite Amps PTE-Qx


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