The acoustic feedback (AFB) system is to detect the acoustic signals radiated from a loudspeaker with a microphone, and feed them back to the previous stage of the amplifier. However, there were many problems to put it into practical use.A new AFB system has been developed, where the above problems are solved by setting the microphone at the optimum position and adopting a new feedback method. This was achieved by reviewing the loudspeaker performance from a new point of view. Thus, a wide-range feedback and the improvement in the speaker response have been obtained. Also, the problems of oscillation have been solved.