GB410960A - Improvements in or relating to sound reproducing instruments - Google Patents

Abstract

410,960. Loud-speakers; microphones. YOUNG, L., and YOUNG, A., (trading as VITAVOX ACOUSTICS), Ashford Road, Cricklewood, London. April 11, 1933. No. 10793. [Class 40 (iv).] A moving coil loud-speaker or microphone comprises a diaphragm assembly consisting of a dome-shaped diaphragm portion 1, a coil-carrying cylindrical portion 2 and a carrying flange 3 adapted to be secured between rings 5, 6 to the inner surface of the outer magnet pole 18 by screws 22, the arrangement being such that the cylinder 2 is constrained against lateral movement at both ends. The rings 5, 6 engage in a recessed portion in the pole 18 to ensure correct centring of the coil in the air gap. If desired, the domed portion 1 may be formed with a concave central portion (Fig. 2, not shown). A horn-carrying dome-shaped throat portion 23 is mounted above the pole 18 and is provided with a concentric projection adapted to register with a concentric groove 26 in the pole 18. This outer pole is secured by screws 19 engaging in plugs 20 in the outer wall of a pot or cup shaped permanent or electromagnet 13, the central pole 14 of which is made hollow and is shaped as shown in order to obtain a high concentration of flux in the gap. In the case of a permanent magnet, a coil consisting of a few turns of large gauge conducting wire may be permanently associated therewith for magnetizing and remagnetizing purposes. When used as a loud-speaker the hollow pole 14 may be closed by a plug 27 but when employed as a microphone, this plug is omitted and the diaphragm may receive the sound waves through the horn and/or pole 14. The Provisional Specification describes the use of the coil centring means described in Specification 400,343.