336,084. General Electric Co., Ltd., Clark, F., and McAinsh, N. J. Sept. 30, 1929. Loud-speakers; magnetic instruments. - A moving coil loud-speaker has the coil former and centring device for the coil formed in one piece. In the construction shown, the frusto-conical diaphragm 8 is actuated by a coil 7 situated in the air gap of a pot magnet comprising a central core 1, end plates 4, 5 and shell 6. The diaphragm is flexibly mounted in a frame 9 which is fixed to the magnet assembly by screws 10, the fixing holes in the frame being slightly larger than the screws to provide for adjustment. The combined coil support and centring device 11, which may be of aluminium or an alloy thereof, consists of a cylindrical part on which the coil is wound, a tapering portion to which the diaphragm is secured by rivets 12 and ring 13, a flat part comprising arms 14 and an outer ring which is secured to support 9 by screws 15 and ring 16. A washer 17 is provided between device 11 and ring 16 and washers 18, 19 between device 11 and support 9, the leading-out wires from the coil, one of which is shown at 20, Fig. 2, passing between the washers 18, 19.