steps until the desired level is reached, but
do not over equalize. Keep in mind the
equalizers can only provide a maximum
level increase of 3 to 9 dB. Parametric
equalizers, though more confusing to the
novice user, allow for more precise control
of feedback frequencies.
Automatic feedback reducers will accomplish the same results as above. They find and
cut the frequencies that are feeding back automatically. The same precautions listed
above apply to feedback reducers as well as equalizers. Automatic feedback reducers
are very helpful in wireless microphone applications. Remember that microphone
placement is crucial to eliminating feedback, and the temptation to wander away from
the ideal microphone position when using a wireless is great. If the performer gets too
close to a loudspeaker, feedback will result; a good feedback reducer will be able to
catch and eliminate the feedback faster than a human operator.
Feedback
One of the most commonly asked questions in professional audio is "What
microphone can I use that doesn’t cause feedback?" The answer to the question
is, of course, that no such microphone exists. Feedback results from a combina-
tion of many factors, including loudspeaker placement, microphone placement,
the frequency response of both devices, and room acoustics.
What is feedback?
Feedback is characterized by a sustained, ringing tone, which can vary from a
low rumble to a piercing screech. Echoes and reverberation caused by room
acoustics, as well as ground buzz and other extraneous noises, are not the same
thing as feedback, and cannot be cured in the same manner.
What causes feedback?
Feedback occurs whenever the sound entering a microphone is reproduced by a
loudspeaker, picked up by the microphone, and re-amplified again and again. The
familiar howl of feedback is an oscillation that is triggered by sound entering the
microphone. The easiest way to create feedback is to point a microphone directly
into a loudspeaker. (We don’t recommend you try this!) Placing the microphone
too close to the loudspeaker, too far from the sound source, or simply turning
the microphone up too loud exacerbates feedback problems. Other contributing
factors are too many open microphones, poor room acoustics, and uneven
frequency response in either the microphones or loudspeakers.
Music
Guide
Educators
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