Gain Before Feedback

Gain before feedback refers to the maximum sound pressure level that can be attained before the sound from a speaker enters the microphone and is amplified a second time, creating a loop that only builds on itself: feedback.

An often not very scientific measure of how loud a sound reinforcement system can be turned up before any open microphone(s) will feed back. The point at which feedback occurs is effected by numerous variables, including atmospheric conditions (temperature, humidity, etc.) so it's not something that anyone considers an objective measure of performance. Instead the phrase is used to state relative differences: "By adjusting the EQ I was able to get 'more' gain before feedback." -- Sweetwater

---