Got A Problem With Microphone
Squeal? Here's How To Fix It...
Why you get microphone feedback
Microphone squeal is caused by feedback. Feedback happens when
the microphone picks up the output sound from your speakers
which it then re-amplifies causing a loop.
The loop is caused by the microphone picking up the original
amplified sound and amplifying it again, then again, then again,
then again...until the sound can't be amplified any more and
something has to give.
Feedback has the capacity to blow your speakers or amplifier,
although it has to be said that most modern amplifiers these
days have protection built in to protect it from any lasting
damage. Nevertheless, feedback is a serious problem. Even if
it doesn't blow your amplifier or your speakers, it WILL drive
you (and your audience) to despair.
Feedback usually presents itself in the form of a bassy boom
or a high pitched ear-piercing sqeal depending on whether your
microphone is picking up low frequencies or high frequencies.
What your microphone should and should not pick up
The only sound your microphone should pick up is your voice.
It should then send your voice to your amplifier which, in turn,
amplifies the sound and puts it out through your speakers.
But if your microphone picks up any other sounds other than
your voice, especially sounds coming from your speakers, it
will then amplify and re-amplify those sounds in a never ending
loop until something gives (usually your audiences ears)!
Feedback is a common problem when singing live. It's more common
in small venues where the microphone can easily pick up the
sound from the main PA speakers. This is because in small venues
you will usually have your main PA speakers fairly close to
you. Your microphone picks up the sound from the speakers and,
hey presto, the microphone starts to squeel and you have a feedback
Also generally the more microphones you have on a stage at any
one time switched on, the more feedback you are likely to get.
This is because microphones will often feedback with each other.
How to cure microphone feedback - Tip 1
Fortunately there are a couple of ways to reduce microphone
feedback when singing live.
First, switch off microphones when they are not in use. For
example, if the compere has a microphone he uses to introduce
your act, switch it off as soon as he's introduced you. If any
others in your band are NOT singing a part in the song that's
curently being performed, tell them to switch off their microphone
during that song.
A microphone which is not in use but switched on is like a sitting
duck - it's just waiting to pick up any rogue feedback frequencies
and cause you problems.
Rule number 1...if it's not in use, switch it off!
How to cure microphone feedback - Tip 2
Next, when singing live, keep your microphone as close to
your lips as possible (but without actually touching your lips).
Keeping your microphone close up to your mouth when singing
live will allow you to reduce the overall volume of your microphone
slightly at the mixing desk end and this is often just enough
to stop the feedback.
I often see singers holding their microphone 6 inches to a foot
away from their mouth when singing...and then they can't figure
out why they are getting so much feedback!
Holding a microphone far away from your mouth is only possible
when you have an exceptionally big powerful voice (because if
you DO have a big powerful voice, then you won't
need so much volume on your microphone and you won't have feedback
But most male and female singers do not have a big powerful
operatic type voice...more than 90% of singers have normal strength
voices. This means that in most cases the microphone needs to
be set at a reasonably high volume level to pick up their voice...and
that means feedback can be a problem. So
if you find yourself in a live music venue where the EQ hasn't
been set by a professional sound engineer specially to suit
that room prior to you singing in it, then keep the microphone
closer to your lips. This will allow you to reduce the volume
of your mic a little and therefore help reduce any feedback.
Just to be clear on this point
(because I know you've probably watched singers on TV holding
the microphone quite far away from their mouth so maybe wonder
why I'm telling you that you can't do this), if
you are in a professional recording studio, a TV studio, or
some theatres, you can often get away with holding a microphone
at an arms length but only because the acoustics in these places
have been professionally set by professional sound engineers
and the speakers have been carefully placed and EQ'd so that
feedback is not a problem.
But you are not in the same venue every day and even if you
are, your PA has not been set up by a professional sound engineer.
So for everyday live music type venues that you will be singing
in with your own PA system, keep your microphone fairly close
to your mouth (except when you hit those big high notes of course)
or feedback WILL be a problem.
How to cure microphone feedback - Tip 3
Another way to reduce feedback is to adjust the EQ on your microphone
channel and take a little off the top-end (i.e. turn down the
This is because most microphone feedback tends to occur more
commonly in the upper/treble frequencies (although bass feedback
does happen too). Bass feedback is more of a loud booming sound
whereas high frequency feedback is more of a high pitched squeal.
Just be careful when using your EQ to cut frequencies though.
If you take too much treble away from your microphone you could
end up with a muffled vocal sound. Take too much bass frequencies
away and you may be left with a tinny or thin sound to your
More expensive mixing desks have more comprehensive EQ settings.
With a really good mixing desk you can scroll through the frequencies
till you find where the feedback is occuring and "cut"
that frequency without affecting any of the other frequencies
- this is without doubt the best way to cure feedback problems.
However this is more the realm of professional sound engineers
so it's probably not the sort of thing a normal singer would
want to spend time learning to do - it is quite an involved
process with quite a large learning curve, although in my opinion
it is worth learning about if you really want to be guaranteed
a good sound everywhere you perform.
Using a Feedback Destroyer
Another option may be to invest in a hardware device called
a "Feedback Destroyer" which pretty much does what
its name suggests.
I had one of these in my live music gigging rack a few years
back and it does a great job. The only reason I stopped using
it was because I prefer to find the feedback frequency myself
and fix it rather than letting the machine do it for me - I
just felt I had more control over my sound that way.
But for anyone who doesn't know how to find feedback frequencies,
set Q factors, and cut them by the right amount of dB's etc,
a Feedback Destroyer machine will do most of all that work for
you and could be an easy-to-use alternative to doing it all
For more information on Feedback Destroyers, click
here and type feedback destroyer in to the product search...