Capacitive motional feedback for loudspeakers
Welcome to the site. Here you can find information about thecapacitive motional feedback method for loudspeakers. This systemcomprises of cylindrical capacitor placed inside the voice coil former of theloudspeaker driver. Please read Tech-section or more comprehensive"white paper"with measurements for more information.Picture on the left also showsthe measurement capacitor as red / green.
Using this feedback method, THD (Total Harmonic Distortion)of a typical loudspeaker driver at lowest frequencies isreduced significantly. In some measurements THD drops belowone fourth (12dB) of the THD of the same speaker driver withoutmotional feedback. Typical drop in THD is about 50% (6dB) at20 Hz. This method can also be used to modify the frequencyresponse of the speaker.
What does motional feedback mean?
Motional feedback in loudspeaker means using some methodfor measuring the motion of loudspeaker diaphragm (usually cone) andusing this measurement to alter the speaker's drivingvoltage and/or current so that the diaphragm moves the wayit is wanted to.
28-Apr-2009:
Forum was removed because most of the traffic was caused by spambots(and because the forum was broken during the change of web-hotel (my bad)).
1-Apr-2008:
This method was presented on the may issue of theHi-Fi Worldmagazine (on sale 31st March 2008). The article"Historically speaking" states:"Servo Speaker's drive unit design - Motional Feedbacklives on!". Although the company called "Servo Speaker"does not exist (at least not currently), the article is veryinteresting read with many technical innovations mostly from the past(as can be assumed from the title).
