GB233495A - Improvements in or relating to combined gramophonic and telephonic sound reproducing means - Google Patents

Abstract

233,495. Graham, E. A. April 3, 1924. Tone-arm joints; tone-arms, resiliently supporting.-Relates to apparatus of the kind in which a sound-duct associated with a telephone receiver is introduced into the sound-duct of a gramophone or the like, in order to enable a single horn to be used for either sound - reproducing instrument. According to the invention, the portion of the telephonic soundduct which enters the gramophone sound-conduit forms a mounting for the tone-arm. In the construction shown in Fig. 2, a member c, which is the end portion of a sound-duct from a telephone receiver (not shown), is formed with a boss e in which is pivoted a pin f fixed to a spider g<1> on which the tone-arm g is carried. The pin f, instead of being fixed to the spider g', may be fixed to the boss e, or integral therewith, and in this case it forms a bearing for the boss g<2> which surrounds it. Ball bearings may be interposed between the boss e and parts j, h respectively, the, latter being secured to the pin f. Fig. 4 shows a modification in which an additional bearing for the tone-arm is provided by a ring of balls i<1>, A further construction is shown in Fig. 5, in which the tone-arm is movable relatively to the pivot pin f, about an horizontal pin m. A counterbalancing spring n prevents undue pressure of the stylus on the record. A valve p, Fig. 4, may be arranged in the tone-arm, to regulate the volume of sound from the gramophonesound-box, or to close the tone-arm entirely. The valve may be operated by an external knob, acting through a spindle s and links r. Specification-. 232,710 is referred to.