EQ (Equalizer)
Definition
A tool for adjusting the level of specific frequency ranges within an audio signal. Used to correct tonal imbalances, remove problematic resonances, or shape the character of a sound.
In Simple Terms
The tone knob for each sound in your mix. Need more brightness? Boost the highs. Too muddy? Cut the lows. EQ lets you shape every instrument so they all fit together without fighting.
In Practice
A high-pass filter at 80 Hz removes low-frequency rumble from a vocal recording without affecting the voice itself. A gentle 2 dB boost at 10 kHz adds air and presence.
Common Confusion
Boosting and cutting are not equivalent operations. Cutting an unwanted frequency almost always sounds more transparent than boosting a wanted one — boosting raises noise and resonance with the desired content, while cutting removes the offending range cleanly. Pro mixers tend to subtract more than they add.
Sources & Verification
- Bristow-Johnson, R. — Audio EQ Cookbook (biquad filter coefficient formulas)W3C
- Bohn, D. A. — Operator Adjustable Equalizers: An OverviewRane Application Notes
- Izhaki, R. — Mixing Audio (3rd ed., EQ chapters)Focal Press, 2017
Last verified: 2026-05-05