The term "feedback" means that part of the sound
projected by a speaker is picked up by a micro-
phone, fed back to the amplifier, and projected
again by the speaker. Above a specific volume or
"system gain" setting the sound system will start
howling and the sound engineer will desperately
dive for the master fader to reduce the volume and
stop the howling.
To increase usable gain before feedback, the mi-
crophone has a supercardioid polar pattern. It 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 maximize gain before feedback, place the main
("FOH") speakers in front of the microphones
(along the front edge of the stage).
If you use monitor speakers, be sure never to point
any microphone directly at a monitor or FOH
speaker.
Feedback may also be triggered by resonances
depending on the acoustics of the room or hall.
With resonances at low frequencies, proximity ef-
AKG D 5/D 5 S
3 Using Your Microphone
3.4 Feedback
Fig. 2: Microphone
placement for
maximum gain
before feedback.
Refer to fig. 2.
17