Stop Feedback Before It Stops You
By Ben BlakesleyGeorge's MusicOh, no. There it is.That dreaded squeal.The audience cringes and turns to look at the sound engineer as if to say "What are you doing?!"
Feedback: Every Musician's Nightmare
Here's how to stop it dead in its tracks.
First, let's make sure we're all aware of what feedback actually is. Simply, a feedback loop occurs when a microphone amplifies a sound source, feeding it to loudspeakers that then feed the amplified signal back into the microphone, feeding that to the speakers that then feed that signal back into the microphone that then feeds thatwellyou get the picture. This sound, amplified many times over, manifests itself as a loud, uncontrollable squealing sound that can burst eardrums and rattle your bones.How do you avoid this uncomfortable situation?Easy. Make some good placement, EQ, and gear choices.
Fast solution: DON'T PLACE YOUR MICROPHONES FACING THE SPEAKER!! This will eliminate the majority of feedback problems. Make sure that your loudspeakers are situated in front of the performer, facing toward the audience.Also be aware that feedback can come from your stage monitors, so make sure that the rear end of your microphones are pointing toward your monitors.Due to the nature of feedback, how close your microphone is to the sound source is also an important aspect to consider. The closer the microphone to the sound source, the less likely you are to have feedback problems because the gain will be set lower on the microphone and the mic will pick up more of the direct source and less of the sounds in the room (including the already amplified sound coming from the speakers).Quick Tip: During soundcheck, turn up the volume on each microphone until it does generate feedback, then mark that spot on your mixer as the Do Not Cross Line. That will give you a visual cue and reminder during the performance.
Often feedback can be mitigated by using EQ or a Notch Filter to remove offending frequencies that typically cause feedback problems. This is particularly helpful for that 'ringing' type of feedback that is often present in churches or with lapel microphones.
In addition to picking the right place for your gear and EQing out any offending frequencies, picking the right gear for the job is paramount.In live situations, using unidirectional, dynamic microphones will make it easier to avoid embarrassing feedback by limiting the sounds that the mic will pick up to just the direct sound source.Additionally, if you want to make your feedback-killing nearly effortless, pick up a Feedback Suppressor to do the work for you! Simply choose your application type and you're off an running without the looming fear that your most intimate musical moment will be interrupted by dirty looks from an audience plugging their ears to avoid auditory destruction.Using these simple tips, you can be a hero at your next gig, solving feedback problems before they start.Now go make some noise!
Ben Blakesley heads up the Marketing and Technology division of George's Music and spends his time fighting feedback to make the world safe for eardrums everywhere.