What is an EQ (Equalizer)?

An EQ (short for equalizer) is a tool that boosts or cuts chosen frequency ranges in a sound, used by engineers to make each instrument clear and to suit the sound system to the room. Every mixing desk has EQ on each channel, and most PA systems have EQ on their outputs too.

How EQ is used at a live show

A sound engineer uses EQ at three points:

  1. System EQ: before the show, the engineer tunes the main PA to the room, smoothing out frequencies the space exaggerates.
  2. Channel EQ: during sound check, each instrument and voice gets its own EQ so they sit together in the mix without clashing.
  3. Monitor EQ: in monitor world, EQ on each wedge or in-ear mix removes the frequencies that cause feedback.

Engineers note their EQ settings and any venue quirks with the show's technical details. Venues coordinate each act's technical notes alongside their performances in Crescat.

Graphic EQ vs parametric EQ

A graphic EQ has a row of sliders, each fixed to one frequency band, which makes the curve easy to see at a glance. A parametric EQ lets the engineer choose the exact frequency, the width of the band and the amount of boost or cut, giving finer control. Most digital desks offer both.

Common EQ moves in live sound

  • A high-pass filter on vocals and most instruments to remove low rumble
  • Cutting low mids on a kick drum to remove a boxy sound
  • Cutting harsh upper mids on bright guitars
  • Small boosts for clarity on vocals, used sparingly
  • Narrow cuts on monitor mixes at frequencies that start to feed back

Frequently asked questions

What does a high-pass filter do?

A high-pass filter cuts everything below a chosen frequency and lets higher frequencies through. On vocals and most instruments it removes stage rumble and handling noise, making the mix cleaner.

What does ringing out monitors mean?

Ringing out is turning up a monitor until it starts to feed back, then cutting that frequency with EQ. Repeating this before the show lets performers have their monitors louder without feedback.

Is it better to cut or boost with EQ?

Most engineers cut problem frequencies first and boost only when needed. Cutting tends to sound more natural and leaves more headroom before the system distorts.

Related terms