Abstract: An audio loudspeaker having an induction motor whose yoke components are formed of powdered iron or other material which is highly magnetically permeable and highly electrically resistive. The oscillating magnetic flux caused by the alternating current applied to the primary coil induces eddy currents in the shorted turn secondary coil but not in the yoke components. This reduces heating of the yoke components, reduces flux modulation, and reduces wasted power.

Abstract: An audio loudspeaker having an induction motor whose yoke components are formed of powdered iron or other material which is highly magnetically permeable and highly electrically resistive. The oscillating magnetic flux caused by the alternating current applied to the primary coil induces eddy currents in the shorted turn secondary coil but not in the yoke components. This reduces heating of the yoke components, reduces flux modulation, and reduces wasted power.

Abstract: An electromagnetic transducer such as an audio loudspeaker, whose diaphragm assembly and motor both have a highly elongated shape in which the long dimension is at least 3× greater than the short dimension. The diaphragm may be obround, and the motor's magnetic air gap may comprise a pair of elongated, parallel, linear gaps. A novel “boxcar” device is used to hold the bobbin and voice coil in an obround shape, maintaining the parallel, linear shape of their elongated sides. The lower suspension may be disposed only at the ends of the motor, enabling the narrowest possible configuration.

Abstract: An electromagnetic transducer such as an audio loudspeaker, whose diaphragm assembly and motor both have a highly elongated shape in which the long dimension is at least 3× greater than the short dimension. The diaphragm may be obround, and the motor's magnetic air gap may comprise a pair of elongated, parallel, linear gaps. A novel “boxcar” device is used to hold the bobbin and voice coil in an obround shape, maintaining the parallel, linear shape of their elongated sides. The lower suspension may be disposed only at the ends of the motor, enabling the narrowest possible configuration.

Abstract: Trace runs for Planar Line Source Transducers (or speakers) are separated into multiple trace circuits which are electrically isolated but occupy the same area on the planar film. The separate trace runs are then driven with different electrical signals with tailored spectral content in order to achieve an overall acoustical frequency response. By having the separate trace runs occupy the same area, the line source nature of the transducer is preserved over the entire intended spectral response of the transducer and the mechanical structure is also kept simple. External spectral filtering circuits are used to pre-shape the spectral signal into each individual trace run and in most cases, the filtering components are passive and inexpensive.

Abstract: Trace runs for Planar Line Source Transducers (or speakers) are separated into multiple trace circuits which are electrically isolated but occupy the same area on the planar film. The separate trace runs are then driven with different electrical signals with tailored spectral content in order to achieve an overall acoustical frequency response. By having the separate trace runs occupy the same area, the line source nature of the transducer is preserved over the entire intended spectral response of the transducer and the mechanical structure is also kept simple. External spectral filtering circuits are used to pre-shape the spectral signal into each individual trace run and in most cases, the filtering components are passive and inexpensive.