Improvements in and relating to Sound-boxes or Reproducers of Talking Machines or Sound Reproducing Apparatus.

摘要

114,258. Harris, H. W. Aug. 17, 1917. Sound-magnifying appliances.-An iris diaphragm is fitted behind the soundbox of a gramophone for regulating the sound. It is formed of pivoted leaves 38 controlled by an arm 33 moving in a slot in the casing 23, which is attached to the plate 26 secured with intervening insulating-material 25 to the back of the sound-box. The arm 33 may be operated directly or by a Bowden wire connected to a lever fitted with a retaining ratchet. A spring may be used to return the diaphragm to normal position.