GB256677A - Improvements in and relating to the reproduction of sound - Google Patents

Abstract

256,677. O'Donnell, P. S. May 11, 1925. Loud-speakers; magnetic instruments.-Relates to sound-reproducing apparatus such as telephonic loud-speakers. According to the invention, tuned gongs are provided in association with the soundemitting diaphragm and are adapted to vibrate sympathetically therewith. In the loud speaker shown, which embodies a conical diaphragm 3 and other features described in Specifications 261,154 and 259,103, a number of tuned gongs 13 are supported by a ring 14 fixed near the open end of the cylindrical casing of the instrument. The gongs are separated from each other by radial baffle plates 15, also mounted on the ring 14, the plates beng tapered as shown towards their inner ends which are fixed to a ring 15a. A glass disc 10 supports the electromagnetic mechanism, and from this disc extend four wooden rods 18 which are bolted to the ring 14. By this means, the gongs are maintained in a slightly tremulous state, which is said to render them more readily susceptible of sympathetic response. Means for transmitting vibrations to the diaphragm 3 through two diamonds in contact, and auxiliary diaphragms 16, are provided as described in the aforesaid Specifications. According to the second Provisional Specification a sound-amplifying device for a gramophone or loud speaker comprises a box or casing partially closed by glass, mica, &c. and containing a number of tuned gongs. The diaphragm of the gramophone sound box or equivalent primary vibrating member sets up sym. pathetic vibrations in the amplifying device, either by direct mechanical connection or by transmission through the air. The third Provisional Specification describes a loud-speaker in which the casing, provided with tuned gongs as in the constructions described above, is a rectangular box having a slotted front. Four thin wooden panels are arranged pyramidally at the back of the box to form a small space enclosing the electromagnet. Adjustment of the contact between two diamonds through which vibrations are transmitted from the magnetic armature to the diaphragm is effected by means of a knob on the end of a rod which carries the main auxiliary diaphragms, the rod extending through the front of the box. The sensitivity of the gongs may be increased by keeping them in permanent slight vibration, by means such as an electric buzzer.