Mixing Tools: EQ

One of your most powerful mixing tools is the EQ, short for Equalizer. An EQ is a device that can splits the sound signal into different pieces based on frequency content. These pieces can then be manipulated to change the frequency balance in the specific track (or mix) you are working with.

The name Equalizer comes from the days of telephone design. Researchers found that when a sound signal is sent over large distance by cable the top end of the signal is attenuated (reduced) leaving the resulting sound muddy and dull. They conceived of a device that would isolate the high en of the signal and boost it accordingly, so that the signal would be "equal" at either end of the conversation. The nature of these first eq's contribute heavily to the classic "telephone sound" and a very similar sound can be used by boosting heavily betweekn 1000Hz - 6kHz.

Many people feel a bit stumped about the EQ, so

here is a quick overview of the controls. To the right we have the Sonnox Oxford EQ. This is a parametric EQ, meaning you have different "bands" with the possibility of sweeping them up and down the frequency range. As with most parametric EQ's, and indeed eq's in general, this one features a HPF and LPF (High Pass Filter and Low Pass Filter) These filters work by choosing a cut-off frequency, and then filtering out all the information below that frequency.

Now lets look at the other bands. There are three controls: The Gain control, the frequency control and the Q-Control. The Gain control controls the gain (Obviously). With this controll you can adjust the amount of level boost or attenuation of each band. THe frequency controll adjusts the frequency at which the band will be working, and the Q-controll affects the "width" of the band. Most bands affect a certain frequency and to a lesser extent those around it. The Q controll changes the amount of spread to either side in the frequency range, making the gain change less or more specific. This, of course has a dramatic effect on the sound.

In Use

So there you have the basic workings of an EQ. What now? Well, lets take a look at a couple of hypothetical situations. Let's imagine that we have a Kick drum track with alot of the cymbals in it. The kick is also a little dull and uninteresting. We can use a HPF to roll off the higher frequencies that the kick information does not occupy, thereby reducing the spill from the cymbals, and a slight boost around 600-800Hz should increase some of the attack of the kick thereby making it more prominent in the mix.

Let's take a look at a vocal track. The track is a bit boomy and dull, and there is not enough airyness to the vocalists voice. Well, we can start by using the LPF to roll off all the frequencies below, say 100Hz to reduce the boomy quality, that may have occured due to the proximity effect. We can toggle the shelf controll on the HF, this changes the HF from a bell shape to a shelving band, meaning it boosts or attenuates all frequencies above a certain point. We can boost a little bit around 10kHz or so to bring out some of the air in the vocal, and maybe a boost around 3kHz for presence.

Considerations

Always remember what Joe Meek said, "if it sounds right, it is right." PLay around with the EQ, because it will be one of your most important mixing tools for shaping the sound, and making room in the mix.

A general rule, and one that is hard to follow is that one should try to avoid boosting to much. Every EQ introduces tonal characteristics and most EQ's change the phase slightly of the effected area, so be sensible there. A slight boost with a wide Q can be just as effective as a large boost with a narrow Q, while introduceing less artifacts.

If you have any questions at all, please post a comment or send me a message and I will be only too happy to answer!