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    • 2. 发明专利
    • Improvements relating to loud-speakers and like sound reproducing apparatus
    • GB371433A
    • 1932-04-20
    • GB183531
    • 1931-01-20
    • GEORGE DONALD MCLEOD BRAGGINS
    • H04R1/28
    • 371,433. Loud-speakers. BRAGGINS, G. D. M., 91, Bloxham Road, Banbury, Oxfordshire. Jan. 20, 1931, No. 1835. [Class 40 (iv).] A loud - speaker comprises a conical diaphragm a , as shown in the Figure, enclosed within a shallow unobstructed cylindrical casing h, having apertures m in its periphery and a central aperture k in one end wall, the chassis d being secured to the end wall round the aperture k and not in contact with the casing at any other point. According to another aspect of the invention, the conical diaphragm a is enclosed within the cylindrical casing h, secured round the opening k to the chassis d, the apex of the diaphragm extending through an aperture in the rear end wall. Further apertures l may be provided in the front wall of the casing which is preferably of plywood. The rear wall may comprise two or more pieces, not in contact with each other and independently secured to the periphery g, so as to respond to different frequencies, Figs. 3, 4 (not shown). A disc q of brass or other metal may be adjustably mounted in front of the diaphragm a and is stated to improve the reproduction of brass instruments. The loudspeaker may be wholly contained within the cylindrical casing.