Abstract: An electrodynamic loudspeaker having a cone diaphragm within which there is arranged a centrally located body which influences the acoustic radiation. This body is formed by an extension of the magnet core of the moving coil which extension is enlarged in the region of the mouth of the cone to form a partial covering of the cone chamber up to about half of the diameter of the cone mouth. The central part of the covering is approximately equal to one and a half times the diameter of the magnet core and forms a closed surface. In the remaining edge area of the covering there are axially arranged passages, the cross-sections of which occupy approximately one-half of this edge area.

Abstract: A switch device for a turntable with a starting device which closes the switch for the drive motor on the one hand by means of a swinging movement of the pick-up arm manually during swinging-in from its support bracket onto the record, and on the other hand by means of a direct current dc low voltage solenoid which is actuated by momentary actuation of an operating service element, the latter being connected with a first contact pair, and a switch-off device which acts automatically with the arriving of the pick-up or reproducing head in the run-out groove of the record, the switch-off device opening the switch for the drive motor and containing a switch for the entire current supply of the device from the power supply mains.

Abstract: A control device, actuatable by electric solenoids, for the drive unit of a tape recorder, in which the tape, in addition to the normal forward for recording and playback can also run fast forward or reverse, all three drive settings being obtainable with only two solenoids, which solenoids act on two opposite arm ends of a T-shaped lever which has a centrally located pivot bearing. The lever can also be translated in a cross direction and is pulled by a spring against abutments which are disposed opposite the solenoids, so that by suitable switching of the solenoids it can be rotated or even only translated. By the translation the normal forward speed can be set and upon rotation the fast forward or fast reverse can be set by the third arm of the lever.