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Motional Feedback (MFB) is an active high fidelity loudspeaker system which was developed by the Dutch Philips brand in the early 1970s. The loudspeakers have built-in amplifiers and feature a feedback sensor on the woofer. The sensor measures the output signal of the woofer and compares it to the amplifier input signal. This results in a very low[clarification needed] 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.
Although the Motional Feedback technology had been experimented with for several years, Philips was the first company to successfully create a working prototype and create a commercial product line of loudspeakers and equipment. The product manager of the Philips High Fidelity group, Piet Gouw, was responsible for the launch of most of the Motional Feedback loudspeakers and other high fidelity equipment. Today[when?], at the age of 86, Gouw is an active member of MFBfreaks.com, the home of Motional Feedback collectors. He shares historical stories and answers questions on the MFBfreaks.com forum.
Today,[when?] Motional Feedback is used by high-end[clarification needed] audio designers. It is said[by whom?] that Tentlabs owner Guido Tent has designed an active subwoofer which uses Motional Feedback technology.
- MFBfreaks.com - Official Philips Motional Feedback (MFB) collectors' website with Piet Gouw stories (in Dutch)
- Another Philips MFB website (in Dutch)
- MFB Patente, Funktion (in German)
- Panasonic MF-800 Motional Feedback power amplifier and speakers from the 1960s using Luxman technology
- Panasonic Motional Feedback Article from the Miami News, October 19, 1964.