Abstract: An audio amplifier has a collapsible power supply coupled to an audio amplifier circuit to drive voltage rails of the power supply in an inverse relationship to the power consumed by the amplifier circuit. A variable gain input stage includes a linear potentiometer gain control followed by a gain stage and buffer to drive separate bass and treble controls, summed before appearing at the input of an integrated circuit amplifier. The main voltage amplification is provided by an integrated circuit, supplied with power by common base circuits to isolate the integrated circuit from power supply induced distortion. Staggered output stages are coupled to the output of the amplifier, the earlier stages having a longer duty cycle and light duty factor, while the later stages having a shorter duty cycle and heavier duty factor. A voltage doubler sensing power drawn by amplifier to modify voltage rails available at the output of the amplifier circuit.

Abstract: A speaker housing includes an air-impermeable first chamber in which first and second speakers, each having diaphragms which vibrate in operation, are so mounted that the rear surfaces of the diaphragms of both speakers face the inside of the first chamber and the front surfaces of the diaphragms of both speakers face outside the first chamber. The axes of the two speakers are perpendicular. The front surface of the diaphragm of the second speaker faces the inside of a second chamber in the housing which includes a slant board oriented at an angle to the axis of the second speaker. The two speakers are driven such that the sonic pressure wave off the rear surface of the diaphragm of the first speaker is effectively coupled from the air-impermeable first chamber through the second speaker, maintaining the pressure within the air-impermeable first chamber substantially constant.

Abstract: A manufacture of fluid handling devices having a variety of different surface contours or appearances features a universal fluid handling component retaining body and a shroud for enclosing the universal body, the shroud being a selected one of a variety of shrouds that are fabricated separately from the body and that are characterized by having a common internal surface configuration for engaging in permanently affixed, or removable relation, predetermined, selected exterior portions of the universal body, and further, that are characterized by having different external or surface contours or appearances, the latter being determined by merchandising or consumer preference.