Feedback Nobody Wants

Whether as a presenter or a member of an audience, we’ve all heard the unpleasant high-pitched noise called feedback when using a PA system for voice or music amplification. Although there’s no guarantee to prevent feedback from occurring, there are some basic steps which can be taken to avoid it.

There are some simple tips on how to properly set up a portable or installed PA system to avoid feedback. Feedback occurs when the amplified sound from a PA system is picked up by a microphone (wired or wireless), it’s then re-amplified and sent back through the PA system again. This creates a loop which generates its own frequency – that howling, screaming sound we hate to hear. Since the distance between the microphone and the PA system has a lot to do with that howling, our first tip is to ensure your microphone is at least 5  feet (10′ is safer) away from your PA system. This increased distance between the microphone and the speaker slows down the formation of the sound loop, diminishing the chance of the feedback developing. Of course this distance isn’t possible when using personal PA systems (such as the VoiceSaver or the PA Pro) which you wear both the speaker and the mic, but the principle of keeping the mic away from the speaker still applies.

The second tip: Do not set up the PA system right next to a wall or in a corner. Setting up the PA system in an enclosed or confined area limits where the sound can travel, making it possible for the sound to bounce back and forth between the microphone, the wall, and the speaker itself. Setting up the PA system in a wider, open area helps reduce the potential for feedback to occur.

The third tip is to always set the PA system in front of the microphone but pointing away from the microphone. Both PA system and microphone are directionally-dependent elements. If the PA system is set behind the microphone, sound from the PA system is more likely to enter the microphone and feedback is nearly guaranteed to happen. Having the PA system in front of the microphone and facing away from the microphone allows the sound to be delivered through multiple directions rather than creating a circulating loop.

Of course, once you have the PA system and microphone set up, you’ll want begin testing how it sounds first at a lower volume level and then increasing it. The higher volume settings on a PA and microphone can increase the likelihood of feedback happening. So it’s important to know the ideal volume setting of your system and equipment before your audience arrives.

See how easy it is to reduce feedback? You can sound like a pro by following these simple tips.

Read the entire “How To” series about PA gear.

This blog was amended 8/2/11 to include the PA419.


Helping teachers and students with educationally appropriate classroom AV equipment since 1947.