Equalization is one of the most difficult parts of recording to get the hang of since there's literally almost an infinite number of possibilities. Most of us learn by experience and usually massive amounts of trial and error, but there are some brief general guidelines that can be an enormous help for those new to the process. They are:
- If it sounds muddy, cut (decrease the level) at around 250Hz. Although you can get that muddy sound from other lower frequencies (especially anything added below 100Hz), start here first.
- If it sounds honky or veiled, cut at around 500Hz. This is where a huge build-up of energy occurs when close-miking instruments because of the proximity effect that naturally occurs with directional mics. Just cutting a bit in this area can provide instant clarity sometimes.
- Cut if you're trying to make things sound clearer. If the sound is cloudy, there's usually a frequency band that's too loud. It's easier to decrease it than to raise everything else.
- Boost if you're trying to make things sound different. Sometimes you don't want clarity as much as you want something to sound just different or effected. That's the best time to boost EQ.
- If you must boost, keep it to a minimum. If you have to add more than 3dB, chances are you're better off finding the offensive frequency band and cutting it instead. The more EQ you add, the more phase-shift that you add as well, which changes the sound in many unpleasant ways that can't easily be fixed later.
- You can't boost something that's not there in the first place. Once again, you're better off to decrease other frequencies than try to add a huge amount, like 10 or 15dB, to any frequency band.
Although there are exceptions to every one of the above guidelines, you'll always stay out of sonic trouble if you follow them.