Abstract: An improved electrodynamic acoustic transducer eliminates or reduces the need for flexible or elastic materials to suspend an internal magnetic element by using both static and dynamic signal-dependent magnetic fields to control its movement. In one implementation, the transducer has a magnet that moves within a surrounding tube. This tube in turn supports one or more electromagnetic coils that generate a dynamic signal-dependent magnetic field that causes the internal magnetic element to vibrate. The surrounding tube also supports one or more magnets whose location on the tube is fixed and whose magnetic fields provide appropriate restoring forces acting on the internal magnetic element. These fixed magnets may be replaced or supplemented by ferromagnetic materials.

Abstract: An in-ceiling loudspeaker is provided which comprises a woofer and at least three tweeters located below the woofer with respect to the ceiling with the woofer and tweeters arranged to radiate direct acoustic signals downwardly and widely spread from the loudspeaker, the three tweeters mounted at acute angles with respect to the horizontal plane which is parallel to the ceiling, the acute angle preferably being approximately 65.degree.. The three tweeters are regularly spaced equally at 120.degree. from each other between the axis of the tweeter and the plane of the ceiling.