Five Easy Tips for Avoiding Feedback During A Live Performance!
Let’s start off on a positive note: just because feedback sneaks into your live set does not mean you are a failure. It’s not always easy to avoid, even for experienced engineers. Although the definition of feedback is simple—a continual loop of sound between an audio input (i.e. microphone) and output (speaker)—the causes can be innumerable and, like a predator adapting and learning new ways to sneak up on prey, feedback can rear its ugly head when you least expect it.
However, the following five tips will help you keep that vicious feedback far away from the eardrums of innocent, unsuspecting audience members:
1. Teach mic technique to the singers: Besides staying on pitch, singers need to be amateur sound engineers. They need to understand that their mic should never move away from their mouth except for sudden increases of volume in their singing—and even then the position of the mic still faces the mouth as they glide the mic backward during their loud notes. Then, after the volume swell, the mic should return back to its place in front of the mouth. Singers often let their mics wander further away from their mouths or fall to their sides. This makes sound engineers cringe because the mic then picks up all sorts of signals from all over the stage and creates feedback loops: a mixer’s nightmare.
2. Turn down the ego of the guitarists: As a guitarist, I’m always afraid the work I put into crafting guitar parts will not be heard in the mix and will thus feel like a waste of time. I tend to overcompensate by turning my guitar volume to what seems like a clear signal in the overall mix—from my point of view on stage, at least. And that’s the problem. I’m in the worst position to judge my volume. If my amp is on the floor facing the crowd, a few feet below my ears, what I’m actually hearing is an off-axis sound. By turning up that off-axis volume to make it comfortable for me, I’m cranking up the direct line of volume that faces the congregation. They’re getting blasted, in other words. The sound person can fix this by propping my amp up at an angle or elevating it on a platform so that it is facing me instead of the crowd. The direct line of amplitude will then blast me instead of the crowd if it’s too loud, and I will not feel the need to crank it up (hopefully). If I have a humble attitude, I will relinquish control of my amp volume, and let the sound person handle it through their mix.
3. Place Front of House (FOH) speakers properly: Never place the FOH speakers inline or behind the microphones of the singers (or any microphones for that matter). Always place them in front of the band. To avoid bouncing the FOH speaker signal all over the room and causing feedback, don’t position them with any angle that turns them even a little towards the wall or towards the band. They should be facing the congregation head-on. If you traced a line along the front of the stage, and then along the side of one of the FOH speakers, it would form a right angle.
4. Don’t mix using the gain knobs: The gain knobs are at the top of the mixing board clearly labeled “gain.” Although, yes, if you turn these up, they will change the volume, you should never use these to mix the band. The function of gain knobs is to ensure that every channel has the equal amount of signal coming through. You will only set these knobs once, before you do any mixing. To properly set the gain for a channel, first turn the gain all the way down. Then slide its fader to zero Db, which is clearly marked alongside the fader about ¾ of the way up. Have the person on that channel play or sing. As they do so, slowly turn the gain up until the signal begins to feedback or peak. You can then turn the gain down a little below this point. Do not touch the gain knobs again. Any volume adjustments from this point will be done from the faders. If you mic the singers and instruments closely, you can keep the gain low, which prevents mics from becoming “hot” and sensitive to feedback.
5. Place monitors properly: If you’re using monitor speakers on stage, place them directly behind microphones whenever possible. Mics pick up sound using a cardioid pattern, which has sort of a semi-circular mushroom shape in the direction that the mic is pointing. The cardioid pattern of the mic doesn’t reach directly behind it, which creates a dead spot perfect for a monitor speaker so that it won’t feed its signal into the microphone.
Turn Down the Band; Turn Up the Congregation
Other helpful tips: only feed essential instruments into the monitor mix to minimize stage volume, mute unused microphones (like when a backup vocalist has a 32-measure rest, and they’re just standing there), use Direct Input (DI) boxes for keyboards (never use amps), and use tape to mark feedback points on your faders so you never push them beyond those points.
Sometimes feedback is happening because the overall volume of the mix is just plain too loud. Turn the master volume of the mix down a little if they’re blasting the venue into smithereens. Of course, in a rock/worship (rock-ship?) concert separate from a church service, turning up to 11 might be the whole point; but when the Bride of Christ has gathered to offer her sacrifices of praise to God on a Sunday morning, make room for her voice. After all, the worship team is there to serve the Body of Christ and facilitate its praises, not blow everyone away like rock stars who are craving the attention of fans.