Motional Feedback

Motional Feedback (MFB ) is a feedback control ( acceleration or negative feedback principle) a loudspeaker Hi- Fi speaker that has been further developed, among others, in the early 1970s by Philips. Who originally invented MFB " Motional Feed Back " can no longer comprehend. The first patent was filed on January 1, 1933 by someone named Smythe.

An accelerometer, including in woofers allows adjustment of the actual membrane movement to the desired audio signal. This allows very low frequencies are generated by relatively small loudspeakers. Also, correct any distortion caused by the housing or the woofer itself, intercepted and compensated.

Since these speakers were (mostly in the Netherlands) made ​​by hand and so the production costs were quite high, they could not prevail on the market, as was popular in the 1980s cheaper home electronics. A similar system with accelerometer is used today in the completely regulated speakers of Friedrich Müller at the company silver sand.

A so-called " servo system " for actively driven bass chassis build now also Velodyne and Linn: The chassis will have an " accelerometer " that measures the membrane movements, which are compared with the input signal, resulting in better controlled by correcting circuits chassis movements leads. According to company information from Linn can be achieved by a practically linear frequency response from 19 Hz.