Simple Explanation

An equalizer where the width of the frequency band it affects stays the same no matter how much you boost or cut.

Concise Technical Definition

A type of equalizer where the filter's Q (quality factor) remains constant regardless of the amount of gain applied. This results in a fixed bandwidth around the center frequency for all levels of boost or attenuation.

Layman-Friendly Analogy

Like adjusting the volume of a spotlighted area on a stage without changing how wide the light shines—just brighter or dimmer, but same focus.

Industry Usage Summary

Widely used in professional audio and live sound applications because it offers predictable control over frequency bands. Constant-Q EQs provide more surgical adjustments, making them ideal for feedback suppression and room tuning. They contrast with proportional-Q EQs, which widen or narrow the affected frequency range depending on gain settings.

Engineering Shortcut

Constant-Q = fixed bandwidth per band, no matter the dB cut/boost. Q = center freq / bandwidth stays stable.

Full Technical Explanation

A constant-Q equalizer maintains a fixed ratio of center frequency to bandwidth (Q = f₀/BW), ensuring that each filter band retains the same bandwidth regardless of gain changes. This behavior results in sharper, more consistent filtering at low or high boost/cut levels. In contrast to proportional-Q designs—where Q varies with gain—constant-Q equalizers are preferred in scenarios requiring precise notch filtering or surgical tonal adjustments. They're standard in graphic equalizers used for sound reinforcement and venue calibration where predictability and control are critical.