GB402600A - Improvements in or relating to loudspeakers - Google Patents

Abstract

402,600. Loud-speakers. KIRKE, H. L., 53, Rodenhurst Road, Clapham Park, London, HOWE, A. B., Shaldon, Hill View Road, Hatch End, Middlesex, and BARRETT, A. E., 62, Lessar Avenue, Clapham Common, London. Nov. 27, 1931, No. 36020/32. Divided on 378,286. Drawings to Specification. [Class 40 (iv).] A body adapted to be associated with an acoustic device, such as a loud-speaker, comprises sound damping material with a flaring passage therethrough, the nature and thickness of the damping material in the neighbourhood of at least one end of the passage being such that a large proportion e.g. 50 per cent or more, of any sound energy of lower frequencies, e.g. 100 cycles per second, falling thereon is absorbed. The invention also comprises a loudspeaker cabinet adapted to accommodate a diaphragm and having in one wall an aperture through which the diaphragm is adapted to radiate sound and having within it a flaring passage at least partially bounded by sound damping material, said aperture being adjacent to the smaller end of the passage and the thickness of the damping material in the neighbourhood of said aperture being not less than one half the diameter of said aperture. The constructions described are identical with those described in Specification 378,286 except that glass silk, cotton wool or acoustic down may be used as alternative damping materials and a modification is described in which the wire mesh former is omitted, the air passage being formed by securing fabric, such as muslin, around the aperture in the front wall of the cabinet, packing damping material fairly loosely between the fabric and the inner walls of the cabinet and then slightly stretching the fabric and securing it around the rear edge of the cabinet.