The following charts can be used as guidelines for tuning / setting an equalizer. This is a skill that takes hours and hours of practice, so don't be frustrated if you find it is taking time to get right.
Frequency RangeEffected AreaResults Of Excessive Boost
16hz - 60hzSense of power, music is felt more than heardMakes music sound muddy
60hz - 250hzFundamentals of the rhythm section. Equalizing can change the musical balance making it fat or thinMakes music sound Boomy
250hz - 2000hzLow order harmonics of most musical instruments horn-like. Listening fatigue may result.Telephone-like quality to music.,br> 500 to 1kHz will be horn-like
1kHz - 2kHz will sound tinny
2kHz - 4kHzSpeech recognition3kHz - Listening fatigue
Will add a lisping quality to voices
M", "V", & "B" will become vague
4kHz - 6kHzEffects clarity and definition of voices and instruments.
The music will seem closer to the listener
Sibilance on vocals (harshness)
Addong boost at 5kHz will make the music seem louder.
6kHz - 16kHzBrilliance and clarity of sounds.Sibilance and/or harshness on voices.

Key Frequencies:
VoicesFullness at 120Hz; Boominess at 200 - 240Hz; Presence at 5kHz; Sibilance at 7.5kHz; Air at 12 - 15kHz.
HarmonicaSounds "Fat" at 240Hz; will add "Bite" at 3 - 5kHz.
CongaResonant ring at 200 - 240kHz; Presence and "Slap" at 5kHz.
Bass GuitarAttack or pluck is increased at 700 or 1kHz; Bottom will be added at 60 or 80Hz. String noise at 2.5kHz.
Bass Drum"Slap" at 2.5kHz; Bottom at 60 or 80Hz.
Snare DrumFatness at 240Hz; Crispness at 1 - 2.5kHz; Bottom at 60 - 80Hz.
Hi-Hat and Cymbals"Shimmer" at 7.5 - 10kHz; "Klang" or Gong sound at approx. 200Hz.
TomsAttack at 5kHz; Fullness at 240Hz.
Floor TomsAttack at 5kHz; Fullness at 80 or 120Hz.
Electric GuitarBody at 240Hz; Clarity at 2.5kHz.
Acoustic GuitarBody at 240Hz; Clarity at 2.5kHz; Bottom at 80 or 120Hz.
PianoBody at 80 - 120Hz; Presence at 2.5 - 5kHz; Crispness at 10kHz; Honky-Tonk sound at 2.5kHz as bandwidth is narrowed. Resonance at 40 - 60Hz.
HornsFullness at 120 - 240Hz; Shrill at 7.5 or 5kHz.