Loudspeaker with flat frequency characteristics

Claim 1

In a loudspeaker construction forming a horn type speaker or the like and including; a casing having an annular plate concentrically surrounding a circular magnet and forming an annular air gap therebetween, a diaphragm having a central portion overlying said magnet, a cylindrical voice coil support extending from the side of the diaphragm facing the magnet and concentrically carried within said annular gap, and an integral peripheral edge portion of the diaphragm overlying said annular plate, a cover overlying the side of said diaphragm not facing the magnet, the improvement comprising: means including at least said cover defining an annular cavity receiving the peripheral edge only of said diaphragm, means for fixing said diaphragm to said casing solely at its peripheral edge with said peripheral edge portion dividing said cavity into two portions on either side thereof of equal size comprising a pair of annular gaskets which sandwich the peripheral edge of the diaphragm and a plurality of holes are provided at circumferentially spaced positions within said gaskets in axial alignment with themselves and with corresponding holes within the peripheral edge of The diaphragm to form a plurality of short length sound passages within the peripheral edge of said diaphragm directly connecting said cavity portions with said passages having a length less than the half wave of the high reproduction threshhold frequency of the loudspeaker.