Motional Feedback

Motional Feedback (MFB) is the name of an active high fidelity loudspeaker system which was developed by the Dutch Philips brand in the early 1970s. The loudspeakers had built-in amplifiers and featured a revolutionary feedback sensor on the woofer. The sensor measured the output signal of the woofer and compared it to the amplifier input signal. This resulted in a very low distortion and furthermore a more extended low frequency response in a relatively small enclosure. Any distortion induced by the enclosure or the woofer itself is immediately corrected by the feedback loop. To a degree, the sensor/feedback system also compensates for non-optimal room acoustics.