Feedback can case a headache in a live sound environment but is something a well trained engineer can easily overcome. Feedback is caused when a microphone is close enough to a speaker that it is being amplified through to cause a squeal. This squeal then stays in a loop because the microphone can hear the squeal back from the speaker so re-amplifies it.
Ways to overcome feedback…
When designing a basic speech sound system for an event a good rule is to place the speakers as far away from the microphone and closer to the crowd as you can. This doesn’t mean at head height on the front row (not only would this cause sound reflection back towards the microphone but would also subject the front row of the crowd to high sound pressure levels. Instead place the speakers 3-6 foot above head hight slightly angled down into the crowed. In most cases wherever you are in the crowd if you can see the front of the speaker you can hear it too, so play with the hight dependant on how large your crowd is.
Correct choice of microphones
Some microphones are more sensitive than others and if you are only trying to amplify spoken work we recommend sticking to a dynamic mic. Dynamic mics are perfect in this environment because they mostly have a cardioid polar pattern- This means they accept sound from the front and reject noise from the back. Note- a dynamic mic is only most effective when used close to the mouth the further away you are to the microphone the more gain you require and the more likely you are to then encounter feedback.
Once you have taken the above into account and still require more gain before feedback then we recommend EQ’ing the system or microphone. This means to analyse the sound (either by ear or meter) and find the ‘problem’ frequencies that are causing the feedback and reduce the gain of that frequency either on a graphic or parametric EQ.
Contact us today for advice or help to overcome feedback at your next event