Abstract: A tunable antenna system for operation over a predetermined frequency range includes a high Q antenna having a length and width each significantly less than a quarter wavelength within the predetermined frequency range. A controllable reactive element is coupled to the antenna and has a variable reactance for tuning the antenna in a high Q resonant circuit to the frequency of a desired signal in the frequency range coupled to the antenna. An antenna tuning circuit responsive to the frequency to which the antenna is tuned provides an antenna tuning signal to the controllable reactive element so that the antenna remains tuned to the frequency of the desired signal.

Abstract: Stereo electroacoustical transducing apparatus for providing acoustical reproduction in a room at least partially bounded by a room bounding surface including a floor, sidewalls, and a ceiling, the apparatus including a nonlocalizable woofer module that is mounted outside of the room and communicates with an opening in the room bounding surface, upper frequency drivers located within the room, and electronics for providing audio electrical signals to the nonlocalizable woofer module and the upper frequency drivers.

Abstract: A vehicle has an engine and a sound amplifying system characterized by a frequency response including a signal source and a manually operable sound level setting control that establishes the sound level of the desired signal in the vehicle, a power amplifier and an electroacoustical transducer. The manually operable sound level setting control comprises a dynamic equalization circuit for providing a predetermined equalization over the bass frequency range depending on the sound level setting of the sound level setting control. A variable gain device associated with the sound level setting control responds to an input electrical audio signal to be amplified by the system for providing a signal of controlled amplitude. The variable gain device controls the gain of the system to increase and decrease in response to the engine being on and off respectively.

Abstract: A multiple driver loudspeaker system comprises two angularly spaced rear rectangular baffles each nearly filled with four closely spaced full-range small loudspeakers with a port tube passing through the center of each rear baffle and the junction therebetween. A front baffle carries a small centrally located loudspeaker. The front loudspeaker is backed by a cavity that is vented through the port tube at the intersection between the rear baffles. Each of the remaining loudspeakers is backed by a cavity with the four cavities associated with each rear baffle being vented through the associated port tube through channels located at the front of each cavity. Two bullets are cantilevered from the front baffle rearward and essentially concentric within the respective centrally located ports. The volume of each of the nine cavities is substantially the same.

Abstract: A sequence of light emitting diodes are progressively illuminated with progressively increasing instantaneous amplifier output signal amplitude with the last pair of light emitting diodes illuminated simultaneously to indicate amplifier clipping.