Patent ID: 6868165
Filing Date: 2005-03-15
Classification: H04R

Abstract:
1. A loudspeaker comprising: a closed-backed magnetic flux path assembly; the magnetic flux path assembly having a pole piece, a magnet, a magnetically permeable front plate, and a magnetic flux path between one pole of the magnet and the pole piece and between the other pole of the magnet and said front plate; said front plate having an opening defined therein sized to fit about the pole piece and to cooperate with the pole piece to define a gap; a diaphragm, a voice coil mounted to said diaphragm, said diaphragm being driven by said voice coil, said voice coil being mounted in said gap; said gap accommodating movement of said voice coil; said diaphragm having a central dust cap; an enclosed cavity being defined within said voice coil and between said dust cap and said pole piece; said magnetically flux path assembly having an enclosed space defined therein about said pole piece; said pole piece having a passageway defined therein, said passageway providing a fluid communication path between said cavity and said enclosed space; and said front plate has venting defined therein external to the voice coil, said venting permitting fluid communication to ambient from said enclosed space through said plate external to the voice coil.