Air motion transformer transducer with closed-circuit magnet motor system

An air motion transformer loudspeaker has a magnet assembly 102 operable to provide a magnetic field and a folded diaphragm 104 having conductive traces and operable to expand or contract in a first direction V and emit a sound in a second direction S perpendicular to the first direction. A ferromagnetic assembly 112 comprises several fixed members 112A-E arranged within the folds 104A-E of the folded diaphragm to provide a closed loop magnetic circuit that drives the expansion or contraction of the folded diaphragm. The fixed members 112A-E may be steel rods (fig 3). Using a closed loop magnetic circuit in this way is said to improve the efficiency of the loudspeaker and to improve loudspeaker sensitivity at high frequencies.