Understanding the dynamics of the frequency range is real important. And knowing how to apply eq to the different parts of your mix can make a difference. I snatched these tips off another board that I thought were pretty good.
For EQing DRUMZ:
Frequency Selection - If your serious about obtaining a clean and punchy sound for your drums, then you'll quickly learn you must be selective in the frequencies you should to boost and cut for each drum track. Most important to remember - Avoid accumulation of the same frequencies. Particularly, avoid over boosting low end frequencies. This will only muddy up your drums, as well as, mask other important tracks in the mix. Ensure your drum frequencies are even across the board!
Clean it Up - To achieve an overall punchier & cleaner mix, try cutting low end frequencies between 250 - 500hz on drum tracks such as kicks & toms. Cutting frequencies in this range will actually sharpen up drum tracks that sound too bold, harsh, & up-front. For punch, try adding 250 - 350hz into your snare & clap tracks. This will give more snap & body to the rhythm, as well as, balance out where your cut previously on your kick & tom tracks.
Adding Clarity - Cutting out the low frequencies from 100-200hz on cymbal & hi-hat tracks will add clarity while also allowing the other drum tracks that contain natural lows in those same ranges to come through in the mix. Also, boosting highs from 9khz - 12khz will add brilliance to cymbal tracks & boosting around 8khz will add crackle to your snare & clap tracks. If your not satisfied with the depth & feel on your kick tracks, then add a 4db boost at 40hz using a narrow Q of around 20. This will give the kick tracks the punch you're looking for. But ...don't forget...high pass your sub kick tracks from 34hz & below, canceling out unwanted low end rumble.
For EQing Bass
1) Bass frequencies are omnidirectional. This means the lows within bass instruments contain alot of power and energy, so powerful they can control the overall output of the master mix level. Plus, your bass track should almost always be panned in the center. Panning your bass other than to the center is senseless as it will only generate a mix that is lopsided and artificially hot on one side.
2) Don't EQ your bass with the same frequencies as you used on your kicks. For example, if you boosted 40-80hz in your kick tracks, then boost around 120hz for your bass, or vice versa. It's very important to avoid accumulation of the same frequencies when dealing with lows as these tracks control the overall output level of your mix. By assigning different frequency settings to each low end track, your overall mix level can become louder.
3) Boosting a particular frequency on a kick track, calls for cutting the same frequency by the same amount on your bass track. Specifically, when boosting 80hz on a kick track, be certain to cut 80hz by the same amount on your bass track. Likewise, if you boosted 130hz on your bass track, cut by the same amount and frequency on your kick track. This secret technique will give your song a far more low end sculpted sound, allowing for a hotter overall mix.
