EQ tips: a basic equalization guide, part two

Having covered EQ (or equalization) basics in his first post in this series, Graeme Allen goes on to look at the three basic types of equalizer that you might find in home recording software such as Garageband.

Before I go into a few fundamentals of EQ mixing I’ll talk about the different types available to you. There are three basic types; shelving, graphic and parametric.

Graphic EQs usually have individual controls for lots of bands of frequencies, allowing you to cut or boost (make quieter or louder) a frequency of your choice. This is the iTunes equaliser, and is a prime example of a graphic EQ:

In the application you can move the sliders to change the sound yourself, or choose a preset. In this instance, the equalizer is set to enhance the sound of a single instrument: a flute. The flute doesn’t have many bass frequences, and they don’t need bringing out because nobody expects to hear too much bottom end from it, so the bass end of the spectrum is left alone. The highest frequencies are left alone, too - any boost there and it might sound shrill. Rather, the instrument is given extra clarity by a shaped boost in the 250Hz - 2KHz range.

Parametric EQ is similar, but you can alter the range of each frequency band. They’re usually a bit more interactive and easier to negotiate too. This is the bog standard one that comes with all versions of Pro Tools:

The parametric EQ in your DAW (and they all have them, including Garageband) is a complex and powerful tool that could be the subject of several long and detailed posts by itself. The best starting point is to record a very simple single track - say a vocal - then dig into your parametric EQ and just play around. Rather than thinking too much about technicalities to start with, just get a feel for how it change your sound.

Shelving EQs are dead simple, and just cut or boost the signal above or below a certain frequency, like this:

An EQ shelf following the lower line would cut the highest and lowest frequences en masse, leaving the mid-range intact. The upper line represents also leaves the middle alone, but boosts the highest and lowest ends of the spectrum. Shelving EQs are good for ‘confining’ particular instruments to particular parts of your mix: for example, you might use one to prevent bass undertones from an acoustic guitar muddying up the mix between the bass instruments.

So that’s the types of EQ. The one you’ll probably end up using the most is the parametric EQ; it tends to be the most flexible, and the most common choice for plug-ins. In fact your DAW will more than likely already have a couple built in.

In the final post in this series, I’ll take a look at some of ways you can use EQ in your recordings.

Graeme Allen is the MD of Amati Studios, a company that works with some of the best mid-sized recording studios in the country.

In addition to his technical skills, Graeme is a first class musician in his own right, playing rock, blues and jazz guitar and classical violin. Visit his website at www.amatistudios.co.uk.