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 circuit for connecting a loudspeaker combination having a treble loudspeaker to an amplifier with a control device for emphasizing the amplification in the range of the treble frequencies, comprising a positive temperature coefficient resistor connected in parallel to a fixed resistor. The parallel resistor combination is connected in series in the electrical connection means for the treble loudspeaker and substantially through the first-mentioned resistor has a value which during normal operation of the loudspeaker combination is smaller than that of the treble loudspeaker, and further has a temperature coefficient such that by exceeding of a permissible constant load voltage for the treble loudspeaker, its resistance value increases with respect to the treble loudspeaker such that the latter is not thermally overloaded. The fixed resistor limits the resistance increase of the resistor combination to a predetermined value.