Patent ID: 7510048

Claim:
A diaphragm for a loudspeaker drive unit, the diaphragm comprising a block of rigid plastic foam material having a first, convex, frusto-conical sound-radiating front face and a second, convex, frusto-conical rear face, each said frusto-conical face being formed by a respective frustum comprising a truncation plane and surrounding conical flank, wherein said block is stiffened by being bound about over said first and second faces by a multiplicity of turns of one or more elongate members of flexible material stiffened by a stiffening composition, said flexible material being wound tangentially to said truncation planes so as to leave interstitial spaces between adjacent turns at the outer periphery of said conical flanks, in which spaces said block of rigid plastic foam material is left uncovered by said elongate members, wherein said one or more elongate members are disposed in low tension so as to maintain said elongate members taut without pre-stressing the same, wherein said one or more elongate members comprise tape wound carbon fibers and said stiffening composition comprises an epoxy resin.