Boston Acoustics, Inc.

David Cahill

Derek Hatchett

Aaron Linn

Andrew G Kotsatos

Carlos Beltran

Wako Iwasaki

Lewis Athanas

A thermal overload and resonant motion control circuit is provided for an audio speaker, the circuit generating a feedback signal to control the input applied to the speaker, which feedback signal is dependent on both the drive current to the speaker and the speaker impedance. More specifically, the feedback signal has a voltage which is substantially equally to the absolute value of K(bv&#x2212;ai)H(s); where,

Thermal overload and resonant motion control for an audio speaker

A planar-type loudspeaker is provided which includes at least two separate, substantially flat, substantially coplanar diaphragms driven by a common drive mechanism. The diaphragms are each of a material and are dimensioned so that each has only a limited number of natural modes of vibration in the frequency band in which it is to operate and that corresponding natural modes for the diaphragms are close enough to achieve beneficial mechanical coupling and acoustics interference so as to provide a generally uniform acoustic pressure response over the selected frequency band. The diaphragms are preferably coupled only through the drive mechanism and it is preferable that each diaphragm have only two natural modes of vibration in the selected frequency band.

Planar-type loudspeaker with at least two diaphragms

An audio speaker, the voice coil of which is passively cooled by using at least one of the speaker cone and spider as a bellows to draw air in and to push air out through a first vent passing through the voice coil and a second vent, connected to the first vent through an air flow path, which second vent is formed in a basket of the speaker which is formed of a material having good heat transfer properties. Air drawn into the speaker through the first vent removes heat from the voice coil and is heated thereby. This air is mixed with cooler air drawn in through the second vent which cooler air is expelled through both vents under appropriate action of the bellows. Partially cooled air expelled through the first vent further cools the voice coil and expelled through the second vent, which is also partially heated, has heat removed therefrom as it passes through the second vent formed in the basket, the relatively large area of the basket passed through by this air functioning as a heat sink. Turbulence in the vents assures air exchange at the entrances to the vents and the drawing of replacement air therein.

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Merrimac, MA, United States of America

David Cahill