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 very low distortion, as any distortion induced by the enclosure or the woofer itself is immediately corrected by the feedback loop. This low distortion also allows for extended low frequency response in a relatively small enclosure. 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, such as G.H. Brodie's 1958 patent on a feedback system using capacitive sensors, Philips was the first company to successfully create a working prototype and create a commercial product line of loudspeakers and equipment,

References

  • MFBfreaks.com - Official Philips Motional Feedback (MFB) collectors' website with Piet Gouw stories
  • Another Philips MFB website
  • MFB Patente, Funktion
  • 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.