Microphone feedback can damage your sound system and be painful to the ears. It is produced when the microphone signal is amplified and picked up again by the speakers, creating a continuous loop. The signal then continues to be amplified at an extremely fast pace until it creates an unpleasant sound. Here are some steps you can take to avoid producing feedback.
Steps
Step 1. Place the microphone behind the main speaker and in front of the spy boxes
If the speakers are too far to the side of the microphone, feedback can occur due to the vocal microphone pickup system. It is best to place the spy boxes directly behind the microphone.
Step 2. Do not close the microphone with your hands
Many singers have a tendency to put their hands around the microphone when performing and this can result in unpleasant high pitched feedback. Keep your hands behind the microphone. If you are walking on stage, be careful not to pass the main speakers and not to point the microphone at the spy boxes.
Step 3. Use a feedback eliminator
They are units that can be rack mounted and can be connected to main speakers or spy speakers. Feedback Eliminators have the ability to spot the impending surge in feedback and cut its exact frequency, eliminating it.
This tool is very useful if there is a change of singer in your performance and the microphone needs to be moved on stage
Step 4. Use a graphic equalizer
This device allows an engineer to prevent feedback during a performance - thanks to a process known as the ringing out of microphones. He will do it before the show, during the soundcheck.
- During the soundcheck, the singer sings into the microphone while the engineer slowly raises the level until feedback occurs. Once started, the engineer finds the correct band on the graphic equalizer and tries to reduce its gain.
- You should repeat this with each microphone during the soundcheck. On a high quality system there are usually 2 31-channel graphic equalizers, 1 for the main mixer and 1 for the monitor mixer.
Step 5. Use the parametric equalizer on the channel strip
Most high-level mixers have a parametric EQ for the mid frequencies which can help you if you need to dampen a specific frequency.
The bandwidth of a parametric equalizer is often much smaller than the bandwidth of a graphic equalizer, and allows for precise control of frequencies. It therefore allows the engineer to reduce the feedback frequency without compromising the tone of the audio
Step 6. Improve the room acoustics
This advice only applies if the room belongs to you. Improving acoustics can prevent excessive reverb, which can increase the likelihood of feedback in microphones.
