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Setting Up a PA System: How to Prevent Feedback

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Hearing the high pitched squeal of feedback can be highly unpleasant. Audio feedback is generated when a signal travels in a loop around an audio system. For example, if you have a microphone and speakers set up on a stage, the microphone will be feeding an audio signal into the PA system which will amplify the signal and broadcast it via the speakers. However, if the sound emitted from the speaker re-enters the microphone, it will begin to loop and will generate feedback. Below is a guide to some steps you can take to reduce the chance that feedback will occur.

Keep the number of microphones to a minimum

If you are going to have several people on stage at once, it can be tempting to offer everyone their own mic. However, doing so drastically increases the chance that feedback will occur. Think about it - the more microphones which are out there, the greater the chance one of them will pick up a signal from a speaker. You should instead set up a couple of microphones which can be passed between the speakers. Having fewer microphones also reduces the chance the different people will attempt to speak over one another.

Make sure there is a large distance between the microphones and speakers

As sound waves travel through the air, they will begin to lose energy. Therefore, by positioning the speakers and the microphones at a large distance, you can reduce the chance that feedback will occur as any sound waves which reach the mic will not have enough power to create a loop. Ideally, you should place the speakers as close to the audience as possible. Doing so will mean that you do not need to turn the gain up very high. Gain is the name given to the amount of power supplied to an amp. Increasing the gain on your PA system mixing desk also increases the chance that feedback will occur.

Use directional microphones

If you are concerned about gain, you should use directional microphones rather than the omnidirectional kind. Omnidirectional microphones pick up sound waves which approach from any direction. However, a directional mic will only pick up sound from a relatively narrow area in front of the mic. Because of this, a directional mic is less likely to pick up a signal from a speaker.

If you would like to find out more, you should contact an audio specialist today.


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