If the level fader is the right hand of any mixing engineer, the equalizer is the left. The 'EQ' is essentially a set of volume controls for specific sections of the full frequency spectrum, so engineers gain control over the level of the bass, treble, or other, more precise slices of the frequency range. Equalizers are just as essential for live sound as they are for recording studios, and are also used to balance the output of any home audio systems. In fact, your phone probably has an equalizer buried somewhere in your audio settings menu.
The EQ: An Audio Essential
If you're mixing audio, then your first job is to strike a rough balance between tracks with your volume faders. A lot of the time, some instruments will want to get in the way of other instruments by invading one another's frequency range. Using an equalizer, you can precisely adjust the frequency response of each instrument to put all the puzzle pieces together neatly so that nothing gets in the way of anything else. A classic issue is when the bass guitar and kick drum get drowned out to the point where you can barely hear them. Here, you can use the EQ to filter the bass frequencies out of the other instruments to clear space for the bass and kick. Sometimes, you can divide the load between the bass and kick, by assigning one as the kind of 'boss' in the sub-bass at around 50 to 60Hz, and the other as the 'punchy' bass at around 80 to 100Hz. As well as hardware equalizers, you can also get software equalisers in the form of effect plug-ins, which can either be specialised or advanced.
Graphic Equalizers
Graphic equalizers divide the frequency spectrum up into a row of faders which can be used to weaken or strengthen a specific frequency range. More simple models have maybe five faders while more complex models will have anywhere up to thirty-one faders, for the left stereo channel as well as the right. The advantage of using a graphic equalizer is that it gives you a clear overview of any frequency adjustments you've made. The disadvantage is that it can be hard to pinpoint the right frequency to adjust if you don't have a trained ear.
Parametric Equalizers
A parametric equalizer controls one or more 'bands', and each band will be kitted out with a gain and a frequency control. Using the gain control, you can weaken or strengthen a specific band, and with the frequency control, you can select the part of the frequency spectrum you're adjusting. The advantage of a parametric equalizer is that you can easily pinpoint overbearing or lost frequencies by dipping or boosting a band with the gain control before scanning through the spectrum with the frequency control. The disadvantage of a parametric equalizer is that it doesn't offer the clear overview that a graphic equalizer does.
Frequently Asked Questions About Equalizers
What does 'equalizer' mean?
Equalizer means exactly what it says - a chunk of hardware or software that's able to correct and balance the frequency response of audio.
How do you set up an equalizer?
Unfortunately, equalizer presets are rarely any use, so learning to set one up yourself is wise. First of all, your EQ settings will rely entirely on the audio you're working with, so listen closely to the space that each instrument occupies in the whole mix, then weaken the frequencies of the other instruments that might be getting in the way while strengthening any of the frequencies that are getting lost.
How does an equalizer work?
You could see an equalizer as one or more volume controls for specific slices of the entire frequency spectrum. So the bass, middle, and treble controls of your average stereo system are a basic example of an EQ.
How do I connect an equalizer up to my amplifier?
If you want to have control over the tone of the master output of an audio mixer or an audio source like a CD player, then you can connect the master output of the source up to the input of the equalizer. The output of the equalizer can then be connected to the input of your amplifier.
