Abstract: An electromagnetic transducer includes a diaphragm movable relative to a central axis, a magnetic assembly axially spaced from the diaphragm, and a magnetic gap annularly disposed about the central axis. A voice coil is coupled to the diaphragm and includes spaced first and second coil portions which are at least partially disposed in the magnetic gap. A housing includes a rear frame surrounding and supporting the magnetic assembly, the rear frame having an annular well portion in fluid communication with the magnetic gap. At least one channel is formed in the rear frame in fluid communication with the well portion and extends outwardly beyond the well portion in a radial direction. A vent is provided on an outer surface of the rear frame in fluid communication with the at least one channel, wherein air exits the transducer via the vent to transfer heat from the transducer to the ambient environment.

Abstract: An electromagnetic transducer includes a diaphragm movable relative to a central axis, a magnetic assembly axially spaced from the diaphragm, and a magnetic gap annularly disposed about the central axis. A voice coil is coupled to the diaphragm and includes spaced first and second coil portions which are at least partially disposed in the magnetic gap. A housing includes a rear frame surrounding and supporting the magnetic assembly, the rear frame having an annular well portion in fluid communication with the magnetic gap. At least one channel is formed in the rear frame in fluid communication with the well portion and extends outwardly beyond the well portion in a radial direction. A vent is provided on an outer surface of the rear frame in fluid communication with the at least one channel, wherein air exits the transducer via the vent to transfer heat from the transducer to the ambient environment.

Abstract: An electromagnetic transducer includes an electromagnetic dual-coil or multi-coil driver having at least one spacer member placed between at least two permanent magnets. The inclusion of at least one spacer member increases the axial dimension of the magnetic assembly of the driver so that the magnetic gaps in a dual-coil or multi-coil driver are moved farther apart than would occur with a corresponding electromagnetic driver using a permanent magnet instead of two permanent magnets separated by a spacer member.

Abstract: An electromagnetic transducer includes a housing, a diaphragm, a conductive coil, and a magnetic assembly having a plurality of air passages. The coil communicates with the diaphragm such that a flexible portion of the diaphragm is movable in response to movement of the coil. The coil includes axially spaced first and second coil portions. The magnetic assembly is disposed in the housing and is axially spaced from the diaphragm by an interior region. The coil portions are at least partially disposed in an annular gap formed in the magnetic assembly. Each air passage communicates with the interior region and with a respective aperture of the housing. The air passages provide respective air flow paths between the diaphragm and the ambient environment. Air flow through the passages is affected by movement of the flexible diaphragm portion for transferring heat from the transducer to the ambient environment.

Abstract: An electromagnetic transducer includes an electromagnetic dual-coil or multi-coil driver having at least one spacer member placed between at least two permanent magnets. The inclusion of at least one spacer member increases the axial dimension of the magnetic assembly of the driver so that the magnetic gaps in a dual-coil or multi-coil driver are moved farther apart than would occur with a corresponding electromagnetic driver using a permanent magnet instead of two permanent magnets separated by a spacer member.

Abstract: Loudspeaker and other transducers of the dual-voice-coil/dual-magnetic-gap type can be improved by the addition of one or more annular shorting rings strategically located in the vicinity of the two magnetic gaps. The shorting rings have no effect on a steady state magnetic field but act in opposition to any change in flux density or any displacement of the flux lines such as those that occur under the loading imposed when the voice coils are driven hard with audio frequency current. The location of the shorting rings determines their effect: location close to a voice coil reduces the voice coil inductance, location entirely within the magnetic flux loop centerline favors reduction of second harmonic distortion and higher order even harmonic distortion, a centered location on the flux loop centerline, i.e.

Abstract: Loudspeakers and other transducers of the dual-voice-coil/dual-magnetic-gap type can be improved by the addition of one or more annular shorting rings strategically located in the vicinity of the two magnetic gaps. The shorting rings have no effect on a steady state magnetic field but act in opposition to any change in flux density or any displacement of the flux lines such as those that occur under the loading imposed when the voice coils are driven hard with audio frequency current. The location of the shorting rings determines their effect: location close to a voice coil reduces the voice coil inductance, location entirely within the magnetic flux loop centerline favors reduction of second harmonic and higher order even harmonic distortion, a centered location on the flux loop centerline, i.e.

Abstract: Loudspeaker and other transducers of the dual-voice-coil/dual-magnetic-gap type can be improved by the addition of one or more annular shorting rings strategically located in the vicinity of the two magnetic gaps. The shorting rings have no effect on a steady state magnetic field but act in opposition to any change in flux density or any displacement of the flux lines such as those that occur under the loading imposed when the voice coils are driven hard with audio frequency current. The location of the shorting rings determines their effect: location close to a voice coil reduces the voice coil inductance, location entirely within the magnetic flux loop centerline favors reduction of second harmonic distortion and higher order even harmonic distortion, a centered location on the flux loop centerline, i.e.