AKG Emotion C 900 Mode D'emploi page 17

Feedback is the result of part of the sound pro-
jected by a speaker being picked up by a micro-
phone, fed to the amplifier, and projected again
by the speaker. Above a specific volume or
"system gain" setting called the feedback
threshold, the signal starts being regenerated
indefinitely, making the sound system howl and
the sound engineer desperately dive for the
master fader to reduce the volume and stop the
howling.
To increase usable gain before feedback, the
microphone has a cardioid polar pattern. This
means that the microphone is most sensitive to
sounds arriving from in front of it (your voice)
while picking up much less of sounds arriving
from the sides or rear (from monitor speakers for
instance).
To get maximum gain before feedback, place the
main ("FOH") speakers in front of the micro-
phones (along the front edge of the stage). If you
use monitor speakers, be sure never to point any
microphone directly at the monitors, or at the
FOH speakers.
Feedback may also be triggered by resonances
depending on the acoustics of the room or hall.
3 Using Your Microphone
3.4 Feedback
Fig. 4: Microphone
placement for
maximum gain
before feedback.
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