GB314683A - Improvements in and relating to sound reproducing apparatus - Google Patents

Abstract

314,683. Bailey, W. C., and Tweedy, W. July 10, 1928. Gramophone pick-ups; magnetic instruments. -In machines adapted to reproduce sounds from records by causing the stylus bar to vibrate. a diaphragm and also, when desired, an armature in a magnetic field which controls an electric circuit whose current in turn controls an amplifying circuit, an arm 10 projecting from the stylus arm 3 has an armature rigidly connected thereto. The arm 10 may itself constitute the armature. A horseshoe magnet 5 with pole pieces 6, 7, Fig. 2, surrounded by solenoids 8, 9 may be used. There may be a second electromagnetic circuit with armature 11 on the other side of the stylus mechanism, as shown in dotted lines on Fig. 1. The two armatures may be of different shapes or thicknesses so as to emphasise certain portions of the scale or bring out other vibration characteristics. The magnet 5 may be adjustable relative to the armature, being supported from a bar 14, Fig. 4, by bolts 12, with springs 15. An arrangement is shown in Fig. 5 in which the armature 18 and stylus arm 3 extend in opposite directions from the stylus socket 17, an additional armature 20 in line with the stylus socket being provided, if desired. The poles of the electromagnets may be parallel to one another or at an angle. Fig. 6 shows an arrangement in which the poles are at an angle of 60‹, their end faces being chamfered so as to be parallel with the armature.