A product category that has become popular in the last 15 years. The Feedback Eliminator is a type of automatic, electronic equalizer. They work by finding the frequency of feedback and then tuning a precision, narrow bandwidth equalizer to it and cutting the level of that exact frequency until the feedback stops. A good feedback eliminator can go through this entire procedure in a few milliseconds, which means feedback can be stopped and controlled before it gets out of hand. It also means they can be used very effectively in live situations where feedback may occur at different frequencies over the course of a performance (for any of a dozen reasons). Like most product categories that have reached maturity, feedback eliminators come in many different configurations, brands, and price ranges. There are many different capabilities available within the general category, but for the most part the basic purpose is the same: to control feedback problems.