By Full Compass LiveFrom Jimi Hendrix to Sonic Youth, feedback has been used as a powerful musical tool, but most of us want to avoid it whenever possible, particularly in professional settings. Here’s some information to help you understand how feedback happens, and how to prevent it.
What is Feedback?
Feedback is a (usually) unintentional and unpleasant sound that is created when the amplified sound from a speaker re-renters the sound system through a microphone. It is then amplified again and again in a loopDefinition:
1. To re-record dialog over video. See ADR. 2. To replay a portion of audio or video content. 3. (sampling) To repeat a section of a waveform so that it can sustain indefinitely. 3. To repeat a phrase or section of sound multiple times within a composition or recording., and can have many sounds, from a low tone to the typical shrieking sound. Whenever you have a microphone, an amplifierDefinition:
1. A device that increases the voltage or power of a signal. 2. In music performance, a device such as a guitar amplifier that includes speakers and controls to increase the sound level of acoustic or electric instruments., and at least one speaker, you have the potential for feedback, even in relatively simple setups like a conference call.
There is no one issue that causes feedback, but several things have the potential to cause it:
- Placing the microphone too close to the speaker
- Placing the microphone too far from the sound source
- Setting the volume on microphones too high
- Using a greater number of microphones than you actually need
- Not turning off microphones that are not in use
How Your Microphone Choices Can Help You Control Feedback
All of the feedback-causing problems listed above have one thing in common: They involve microphones. Choosing the right microphone and using it correctly is often the key to solving your problems with feedback. There are many types of microphones to choose from, and they all have different attributes and benefits for different situations. Condenser microphones pick up a lot of sound from many different directions, while cardioidDefinition:
A microphone's heart-shaped directional pickup pattern. or directional microphones (which can be both condenserDefinition:
An archaic term for Capacitor. and dynamic microphones) pick up sound only from one focused direction and source. Which of these two will control feedback better? If you guessed cardioid, you are right.
Cardioid microphones are only sensitive to sound that is coming from the area directly in front of the microphone. Very little sound that is coming from the rear and sides of these microphones is picked up. This makes them very useful in reducing feedback during live performances, or events where several microphones are being used at once. They can also be useful for recording sounds with a concentrated source, such as vocals.
In addition to selecting the right microphone, it’s also important to consider the way that it will be used in order to reduce feedback. Here are two tips that you can implement today, with no new equipment needed:
- Cardioid microphones pick up the least amount of sound from the rear, or end of the mic, so it’s ideal to keep the end pointed away from the monitors or speakers as much as possible. Make sure that you help performers understand this, and instruct them to keep the microphone pointed away from the speakers at all times.
- Position your microphones as close to the sound source as possible, particularly when you are working with multiple loud musicians or a very busy and noisy room. This will cut down on feedback between the various sources, which is something that will make both your performers and the audience happy.
- Remember that less is more. Turn off any microphones that are not in use, and turn down any that are too loud.
If you have any more questions about picking out the right microphone for the application, a Full Compass Product expert is only a phone call away: 800-356-5844, M-F, 7-5:30 CT.
