Let’s face it, feedback is a nightmare. No one likes a squealing mic stealing the show in the middle of an intimate ballad or a heart-felt anthem. When you first start out on stage, feedback can seem mysterious, but once you’ve got a handle on what causes it, it’s not rocket science to prevent it.
Here we’ll go over a few basic, common-sense mistakes that cause feedback on stage.
Bad House Speaker Placement
In case it’s not obvious, feedback is simply what happens when a loop is created between an audio input and output. AKA when a mic captures the output of the speaker it’s already outputting to. We’ve all heard the resultant squeal.
The number one way this happens may seem obvious to experienced musicians and engineers: the mic is pointed at the speaker and the speaker is pointed at the mic!
This means you should never place house speakers behind mics. Instead, make sure they’re out front.
Holding the Mic Wrong
Some singers like to hold the mic by its capsule – aka they cup the mic. This causes a change to the acoustic space around a mic which can amplify residual signal from the stage –aka it can cause feedback.
Similarly, placing a hand over the microphone - say if you’re resting a palm on the mic while a solo is played for example - creates the same kind of feedback.
Bad Monitor Placement
Sometimes monitors cause feedback because they’re placed in a bad place. This isn’t always obvious before it happens because feedback from monitors can depend on the polar pattern of the microphone. If your vocal mic has great side rejection, then you can probably get away with having a monitor placed at an angle in front of you.
However, if your mic still picks up sound at the sides of the capsule, you probably want your monitor directly in front of you.
Stage Volume Too Loud
If you haven’t managed your stage volume correctly - starting with the drums – you’re likely to have to crank vocal monitors so the singer can hear. At some point, you’ll crank them so loud that it doesn’t matter where they’re pointed, they’ll feedback. This problem may be the most common cause of feedback with full bands.
Compression
Finally, overuse of compression can be a problem when it comes to feedback. Compression can be a great tool on stage, especially for vocals, but if a signal is on the verge of feeding back, compression might very well put it over the top when make up gain is applied. As a rule of thumb, be careful with compression on stage, especially if you’re already treading the feedback line.
Feedback is no fun (unless used intentionally ala The Beatles “I Feel Fine”), but as you can see, it’s not necessarily that hard to prevent – even without resorting to drastic EQ adjustments or using automatic feedback removers. Even if you do end up needing to twist a knob or two, make sure you eliminate the commonsense errors first.
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