We’ve all been there: the band starts playing, and what begins as a mild, soft high ringing sound suddenly becomes a harsh and overpowering squeal that overwhelms the sound of everything else and makes everyone cover their ears. While a guitarist playing musical feedback can be a beautiful thing, feedback from stage mics is not. Here are some suggestions to control horrible, annoying stage feedback.
Sound Waves Are Directional
Sound waves are directional and they reflect off of surfaces in the room. If the stage and venue are small and the band is playing at thermonuclear volume level, those sound waves are going to bounce off the walls, ceilings, and even the players onstage, sending the monitor signal right back into the mics, creating feedback. So the first thing to do in the quest to control or eliminate stage feedback is to try to keep the stage volume to the absolute minimum level the band is comfortable with.
Mic and Monitor Placement
Next, consider mic and stage monitor placement. A mic pointing straight at a monitor will amplify the signal exiting that monitor, thus producing feedback. Pay attention to placement and try to set up so that you can orient your microphones for maximum rejection in the direction of the stage monitors. B
Keep Your Distance
Keep each mic as close to its source as possible. This reduces the need for the sound engineer to have to add gain at the mixing desk for the PA, and it reduces stray signals from being picked up by the mic. It also helps if you can keep signal sources separated as much as possible, so the mic picks up its voice or instrument with minimal leakage.
Tweak the EQ
Finally, the sound man will be able to hone in on the frequencies that are feeding back the most and reduce or remove them at the mixing desk. This is always the option of last resort, however, because when you cut one frequency, often others are reduced, and the sound can become odd and “notched out.” It’s best to reduce feedback as much as possible at the source — on stage, using the tips above — before you start cutting frequencies at the mixing desk. This will allow for less EQ tweaking and better overall control of feedback.