Feedback is a microphone hearing its own signal come back out of a speaker loud enough to re-amplify itself. It always has a cause — a specific frequency, ringing between a specific mic and a specific speaker. You can find it and fix it in under a minute once you know the pattern.
Find the frequency
- Identify which mic is ringing. Mute channels one at a time on the monitor or main mix until the ring stops — that's your channel.
- On that channel's EQ (or a dedicated feedback-finder plugin if the board has one), sweep a narrow boost up and down the spectrum. The frequency where the ring gets louder and more obvious is the culprit. It's almost always somewhere between 1kHz and 4kHz for handheld vocal mics, or lower (200–500Hz) for boomy stage monitors.
- Once you've found it, cut that frequency instead of boosting it — a narrow cut of 3-6dB is usually enough.
In the moment
Can't find it fast enough during a live moment? Pull the fader on the ringing channel 3-4dB first. Stop the ring, then go find the frequency during the next quiet section.
Prevent it before it starts
- Mic position: keep the mic pointed away from monitors and mains, not toward them. A vocalist "cupping" a handheld mic over the grille also causes feedback — remind them not to.
- Gain staging: unity gain with headroom beats a hot input. A mic gained too high feeds back at a lower volume than one gained correctly.
- Monitor wedges: aim them so the mic's pickup pattern (usually cardioid, rejecting the rear) faces away from the wedge.
Recurring ring in the same spot every week?
That's a room mode or a monitor placement issue, not a one-off mistake. Notch that frequency permanently on the channel or the monitor bus EQ so nobody has to rediscover it live.