GB574435A - Improvements in or relating to phonographs - Google Patents

Abstract

574,435. Gramophones. SOUNDSCRIBER CORPORATION. Dec. 9, 1943, No. 20612. Convention date, Oct. 29, 1942. [Class 40 (ii)] A gramophone recording or reproducing head is pivotally mounted approximately at its centre of gravity in the forked end of the recording or reproducing arm and is spring- urged against the record so that the effect of gravity is eliminated and the stylus engages the record with constant pressure at all times. The invention is applied to the recording and reproducing heads 24, 39 of a combination recording and reproducing machine utilising a record 13 of aluminium or plastic sheet. The recording head 24 is pivoted near its centre of gravity on screws 26, 27 between the prongs 19, 20 of the forked end of a comparatively wide, flat-shaped arm 14 carried by a vertical pivot 15. The recording stylus 25 is pressed against the record by the action of a coiled tension spring 32 stretched between a tailpiece 29a on the recording head and a lug 32a on a bar 33 held above the arm 14 by two rods 34, 37, one of which is screw-threaded and provided with a pair of nuts 38 to clamp the bar 33 at the requisite height to give the desired tension in the spring. The recording head is hollowed out underneath to reduce weight. The screwthreaded joints between the recording head and its pivots have a damping action. The pick-up 39 is similarly mounted; but its supporting arm 16 is narrower, and the pivots are conical points 42, 43, little damping being required with the lighter pressure of about half an ounce required on the reproducing stylus. Specifications 539,534 and 558,552 are referred to.