If you’ve recently started running sound or can’t seem to stop the ring of feedback happening in your system, then the following tips will help take care of that in no time.
And if you’ve been running sound for a while, you may feel like you have a handle on this topic. That’s great! Check out these suggestions to see if there is something you can use to help pass on the info to a new volunteer.
Before we stop feedback, let’s just paint a picture of what it is.
Feedback is simply the amplified sound of an audio signal being picked up by the same microphone that transmitted the signal and then sent through the sound system again, or re-reinforced.
This creates a loop that will go on and on, until it is stopped or until a loudspeaker is damaged.
Here’s a picture of that loop:
There are a few ways to stop this feedback loop. Let's start at step 1.
NOTE: This is the FASTEST way to stop feedback if it ever happens in your sound system.
Without being too drastic about it, simply turn down the main output level of the loudspeakers. Or if you can find the offending microphone channel fast enough, turn it down.
Here’s the important thing: you’ll often only need to turn down the level a small amount to stop the ringing.
This volume adjustment can sometimes be imperceptible to the listening audience, but can make a big difference in the quality of the overall sound.
Monitor loudspeakers on stage can cause feedback too.
Sometimes you just need to turn down the individual input level/mix in the appropriate monitor channel, or turn down the monitors altogether. Just be mindful of how these changes can affect the musicians, singers, or presenters on stage.
You need to get feedback under control, but you don’t want to compromise the quality of the performance or presentation in the process.
As you train your ears and truly listen attentively to the sound in your mixing environment, you’ll be able to hear when things are getting out of balance and when feedback may be getting ready to “take off”.
I’ve had to mix many events where the right microphone was not available for the application or the presenter was constantly moving in front of loudspeakers. In these scenarios, you’ll want to be very vigilant and ready to “ride the fader” of any channel that is on the verge of feedback.
You may find yourself moving the volume level up and down in small increments in order to maintain a stable mix. While this can be a useful short-term solution in the middle of a live event, it is best to experiment with better mic placement and EQ so that constant level monitoring and volume adjustments do not become a persistent distraction.
Most microphones and loudspeakers for live sound are directional. Simply moving a microphone or loudspeaker out of the pickup or projection pattern of the other can greatly reduce the chance of feedback.
Don't place a microphone in front of a loudspeaker, and conversely, don't place a loudspeaker behind a microphone.
One of the most reliable methods to stop feedback is to move the microphone closer to the source.
This allows more of the audio signal to reach the microphone from the true source than from the reinforced signal of the loudspeakers.
Another common cause of feedback in churches around the world is the improper placement of clip-on lavaliere or "lapel" microphones.
While these microphones can be very convenient for clipping onto a variety of clothing or accessories, they are often placed too far away from the presenter's mouth to be effective for live sound reinforcement.
This is an especially troublesome scenario in small and medium facilities where the presenter, often the lead pastor, is speaking near the main loudspeakers.
These microphones should be placed high on the chest of the presenter. This gets the microphone closer to the mouth and therefore provides a better signal level.
Clip-on and handheld mics positioned too far away will be a major contributor to poor signal quality and potential feedback. I always recommend placing lapel mics about halfway down the sternum, 6-8" below mouth.
Another alternative is to use a headset or earworn microphone. The reason why these are so effective at reducing the chance of feedback is because they are positioned so close to the mouth.
This close proximity of the mic to the source provides excellent "gain before feedback" and will let you get much louder volume levels than if the mic were located farther away.
If you have feedback and you can’t turn it down or move it, EQ it.
It’s amazing what you can pull off with a little finesse on the equalizer. Even a basic High/Mid/Low EQ with sweepable mids on an analog console or a parametric EQ on a digital console can be a huge asset for stopping feedback when you hear it.
But be careful!
Try to make incremental and modest adjustments to your channel EQ when using it for feedback. A little bit can go a long way, and it will definitely impact the overall tonal quality of the audio source you are adjusting.
Here’s something else you may not have known:
Feedback is often a lower frequency than you might suspect.
We may think that the fundamental feedback frequency is very high at first (e.g. 4,000 Hz or 4 kHz), but often the root feedback frequency is much lower (e.g. 630 Hz).
When applying EQ for feedback, start with low-mid frequencies around 400 Hz and work your way up.
The acoustic energy on the stage or platform can often build up in the lower frequency range. As the energy in this range increases and builds on stage, it can cause a low frequency feedback loop.
This type of feedback loop potential can often be reduced by engaging the “low cut filter” (or “high pass filter”) on the microphone input channel of the mixing console.
One of the most convenient and fastest ways to eliminate feedback is by using the sweepable mid EQ on an analog console or the parametric EQ on a digital console.
Here is an easy and effective feedback solution:
Properly adjusting the EQ settings can even allow you to raise the overall level of certain channels in your mix.
Just be careful! Turning everything up will likely cause many of the same feedback problems you had to begin with before the adjustments you just made.
Assess each microphone and input channel on its own before adjusting an entire mix level.
So there you have it! We’ve just learned three of the most important tips to help you stop and prevent feedback at church.
Again, those 3 feedback tips are:
#1 Turn it down!
#2 Move it!
#3 EQ it!
Looking for more tips and tricks to stop feedback? There are many more details listed in the “Feedback Killer Battle Plan” guide.
Use this guide to help you confidently prevent and stop feedback.
I hope these tips can help you get even better sound at your church!
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