354,514. Reproducing and recording music. GRAMOPHONE CO., Ltd., Hayes, Middlesex, and WHITAKER, A., Prestwick Place, Gerrards Cross, Buckinghamshire. July 3, 1930, No. 20229. [Class 40 (iv).] An audio-frequency amplifier 2 is associated with a multi-switching device so that the input terminals 3, 3a of the amplifier may be connected either to a radio receiver 1 or to a microphone 7 or to a phonographic pick-up 6, and its output terminals 4, 4a may be connected either to a loudspeaker 5 or to the pick-up 6 functioning as a recorder. As shown the input terminals 3, 3a are connected to two arms 11, 11a of a rotary fourposition switch, the other two arms 12, 12a of which are connected to the output terminals 4, 4a. In position (1), the pick-up 6 is connected through the amplifier 2 to the loud-speaker, for reproduction from a record. In position (2), the microphone 7 is connected to the pick-up 6 for making records. Position (3) connects the radio receiver 1 to the pick-up for recording radio signals, and position (4) connects the radio receiver to the loud-speaker 5 for normal radio reception. A fifth position may connect the microphone 7 to the loud-speaker 5. Tone-correcting devices may be arranged in the circuits, and may be switched in or out by the switch. Extra contacts may be provided (1) to control the gain of the amplifier, (2) to control the phonograph motor, (3) to switch a condenser across a third coil on the microphone transformer (not shown), thus impeding the lower frequencies during the process of recording from the microphone or the radio receiver or both.
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