Abstract: A water heater is disclosed having a heat exchanger, a main burner means for heating the heat exchanger, a standing burner, a main fuel passage means for supplying fuel to the main burner, a manual valve on the main fuel passage means which is operable by a manual operation member, an automatic valve disposed on the main fuel passage means at a point downstream from the manual valve, the automatic valve adapted to open in response to the pressure of a supply of water at a water pressure sensitive member, and a standing burner fuel passage means for supplying fuel to the standing burner, the standing burner fuel passage means drawing fuel from the main fuel passage means at a point in between the manual valve and the automatic valve.

Abstract: A multi way speaker system comprises an amplifier, frequency dividing network including a plurality of filters, a plurality of speakers respectively responsive to the output signals of the filters, and a summing circuit responsive to the output signals of the filters for producing a composite signal to be fed back to the input of the amplifier to establish a negative feedback loop. Because of the feedback loop undesirable influences by various elements included in the filters are diminished and thus the speakers reproduce audio frequencies with high fidelity. At least one equalizer may be employed in the feedback loop, while auxiliary filters may be used in such a manner that the output terminals of the auxiliary filters are connected to only the summing circuit so that the output signals of the auxiliary filters are added to an output signal of at least one filter of the frequency dividing network.

Abstract: An improved switching means is provided in a loudspeaker system, which includes a power amplifier of direct coupled type having no output condensor to deliver an audio-frequency current to the loudspeaker, to eliminate undesirable effects by rapidly breaking an electrical connection between the power amplifier and the loudspeaker upon cutting off an a.c. power source. The switching means comprises circuitry having a remarkably short "time constant" compared with another circuitry provided outside the switching means but within the loudspeaker system, so that the above-mentioned rapid breaking is accomplished.