GB654378A - Improvements in and relating to electro-dynamic devices for converting electrical oscillations into sound waves - Google Patents

Abstract

654,378. Matting loudspeakers. YOUNG, L., and YOUNG, A. Sept. 10, 1947, No. 24877. [Classes 83 (i) and 83 (ii)] [Also in Group XXXIX] Casting.-The throat and acoustic transformer of a moving-coil horn loudspeaker (see Group XXXIX), is cast in one piece with the slots therein. The throat comprises a hollow cone 15 (Fig. 4) with an integral coaxial solid cone 16 united by the integral solid portions 17 between radial slots 18. The solid portions 17 converge into knife-edges towards the righthand side of Fig. 4. The core parts for each of the slots are made in two parts, one set of fins 19 (Figs. 7, 8) withdrawable in one axial direction with the core 20 for the conduit 13 (Fig. 4), and the other co-operating set of fins 21 (Figs. 5, 6) with the core 22 for the concave portion to receive the loudspeaker diaphragm withdrawable in the opposite direction. The edges of the pins 19 and 21 meet and coincide when the cores are positioned ready for casting, and the core 20 has a conical recess 23 for the formation of the solid cone 16. After casting and withdrawal of the sets of fins, it may be necessary to clean flashes on the surfaces of the slots by drifting. The casting may be performed by injection, flow, pressure or by any of these in combination.