An Equalizer (EQ) is the first plugin you’ll want to familiarize yourself with. It may be the most important plugin involved in mixing, yet it shouldn’t be heard. Let me explain.
When you effectively use EQ, it’s what you don’t hear that counts. EQ is a plugin that helps subtract unwanted frequencies to allow other frequencies to fill the space, making the whole thing sound better. You can use it to boost frequencies, but the key is to subtly subtract what you don’t want.
One of the main things EQ does is balance the tone. EQing a track means you’re balancing frequencies — more of the good, less of the bad. You’re basically balancing the instruments with each other, making sure they all play nice together.
Another important thing EQ does is to remove overlapping frequencies. The more tracks/instruments you have in a song, the more likely it is to sound muddy, especially the vocals. By using subtractive EQ, you can help separate overlapping frequencies.
Let’s say a vocal is overlapping with an acoustic guitar (which is common). This can lead to the listener losing the full effect of one or both parts. Things just get convoluted. Carving out a space for each instruments’ frequencies helps them both stand on their own and sound great together.
A third thing that EQ does for your vocal mix is control it. If a vocal is too muddy, EQ can clean it off a bit. It can help tame harshness in a vocal or bring out the best parts in the Singer’s voice. Basically, EQ helps remove ugly frequencies and boost the pretty ones.