I've been writing a lot about EQ this past week - starting with a basic explanation of frequencies and equalization in Some Good Equalization and Frequency Basics. I've talked a little about how to use an equalizer effect (EQ for short) to improve your recordings by either removing or turning down unwanted frequencies, or boosting certain frequencies. Now we should pull back a bit and talk about the bigger picture. Why should you use EQ? Like a lot of tools in audio recording, once you learn about how cool an effect is, you start to feel like you have to use it all the time. But that is the road to audio hell. Before you use any tool, ask yourself why you're doing it. Does your audio really need the effect? If not, it is better to not apply any treatment. It's kind of like medication. Often we find ourselves just taking it out of habit even if we don't need it anymore. But all things being equal, our bodies, like our audio, are probably better off clean and sober. Don't get me wrong. I'm a big believer in better living through chemistry, and I love me some EQ and compression and reverb on my tracks too. Just make sure you're doing it for the right reasons.
So that being said - what are the reasons for using EQ? Let's review what an EQ is. It is basically a bunch of volume knobs, each targeting a small band of frequencies (this describes a graphic EQ type, as opposed to a parametric EQ where you "dial-in" the frequency and the bandwidth you want to turn up or down), whereas a master volume knob turns up or down ALL frequencies equally. This allows us to JUST boost or cut, say the frequencies around 6Khz. That's usually where sibilance is located, so a reduction in that area can help reduce overly hot "SSS" sounds, for example. So you really should always ask yourself some questions before applying EQ. Graham Cochrane just wrote an article about this called "3 Questions I Always Ask When Using EQ." His questions are:
What Frequencies Are Not Adding to The Track?
What Frequencies Are Hurting The Track?
What Frequencies Make This Track Sound Great?
I think these are excellent questions to help guide yo in the responsible use of powerful effects.
See Graham's explanation of these questions here: