GB191226781A - Improvements in or relating to Sound Reproducing and Transmitting Apparatus. - Google Patents

Abstract

26,781. Derrimann, W. H., [Automatic Enunciator Co.]. Nov. 21. Sound-boxes; microphonic sound-boxes; stylus mountings.-Relates to a microphone sound-box for reproducing and transmitting sounds, in which all parts of the microphone and also the stylusholder and main support are insulated from extraneous vibrations, and in which the sounds are transmitted pneumatically from the reproducing to the microphone diaphragm. T h e Figures show a double differential microphone, though a single one may be used. The microphone diaphragms 16 which are surrounded by granular material 17 are secured between disks 18, and the reproducing- diaphragms 12, 13 between rubber gaskets 14 and the disks 8, 9, felt or like insulating disks 15 being interposed as shown. Bolts 19, surrounded by felt packing 20, bind the parts of the sound-box together. The stylus-holder 21 has its cross-bar 23 pivoted on trunnions 24, screws 27 and rubber washers 28 with or without metal washers 29 serving to hold it in place. The screws 27 pass through side wings on the cross-bar and are locked by nuts 30. The sound-box 9 is supported on a pivot 7 by an arm 5, the pivot 7 being so arranged that only 4¢ ozs. of the total weight of the sound-box is carried by the stylus 22 on the record 23<a>. A knuckle joint 10, which permits the sound-box to be turned .into the position shown in dotted lines, is in two parts 31, 32 connected by pivot pins 34 having lock nuts 35, the part 31 being recessed to allow the part 33 integral with the part 32 to fit into it. A layer of rubber 36 between the parts 6, 31, and rubber tubes 39 and washers 38 round the connecting- screws 37, insulate the sound-box 9 from the supporting-arm 5. The circuit wires are connected through the insulated bolt 41 to the plate 18 and through another insulated bolt (not shown) to the diaphragm 16.