▼Production: Equalisation
Human Hearing
As a child our frequency range of hearing is between 50Hz-20KHz, but as we grow older the high-end of the range decreases to 15KHz and below. Strangely enough, this doesn't mean that we can't notice the difference between music with and without sounds above 20KHz, so don't intentionally remove those frequencies yet.
How We Perceive Frequencies
The further away a sound becomes, the less higher frequency sound remains. This, along with volume, allows you to determine how far something is away and how important it is to react to whatever caused the sound. Equalisation can be used to bring sounds to the forefront and subconsciously influence the listener to react more or less to certain parts of the mix.
Using this Knowledge
If you're mixing the sound of a band, you could make a list of which instruments you think require the most attention and give them their own frequency range in the mix according to how much you want the listener to focus on them. The following is only one man's opinion:
Bass Guitar
Boosting around 80Hz will boost the low bass sounds, while boosting between 500 to 800Hz adds a more aggressive character. Some low-mid cut around 200-250Hz can sometimes be effective in combination with a little low-end bass boost as it warms the sound without making it too boom-y.
Electric Guitar
If warmth is what you're looking for aim at the area between 125Hz and 200Hz. To add attack to the sound the 2-4KHz region is where to do it. If you're mixing two electric guitars you could give them two different areas of the mix.
Acoustic Guitar
You don't necessarily need to EQ this instrument at all. Boosting at the 4-6KHz range will give the guitar a higher jangly sound, and for this you'll need new strings and a good guitar. Body resonance can clash with other instruments in the mix and to stop this you could cut below 200Hz to thin the sound.
Vocals
General brightening can be achieved using a high shelving EQ control. Boosting between 1-2KHz generally doesn't help unless you want to achieve a special effect. Presence can be added by raising the 3-4KHz range sparingly. With backing vocals it can help to roll off some bass.
Drums
Drums in pop and rock records are not the sound of the natural kit, the trick is to make them sound both bright and solid, but not too thick.
Kick Drum
Boosting at 80Hz will give it a punchier sound, but to get a deeper sound try increasing the low shelf frequency control and at around 220Hz. To add definition to the beater impact increase between 3-6KHz.
Toms
Boost between 80-120Hz.
Snare
The sound can be fattened between 90-140Hz while the 'bite' can usually be located between 3-7KHz.
Strings and Brass
Between 1-3.5KHz the sound can get nasally or honky so reducing that range can help the sound. To add high-end character aim between 6 and 10KHz.
Piano
The bass end can be warmed by gently boosting around 90-150Hz while the attack detail can be made more obvious by boosting the 4-6KHz section. If the sound is boom-y look around 250-350Hz and cut.