Abstract: A network for matching an electrical source of audio signals to a piezoceramic driver for a high frequency loudspeaker. The network consists of all of the elements of a bandpass filter network, but with the parallel combination of an inductor and a capacitor in the output stage of the filter replaced by an autotransformer or autoinductor which transforms the input impedance of the piezoceramic transducer into an equivalent parallel capacitance and resistance which, together with the inductance of the autotransformer, supply the load resistance for the filter and replace the capacitor and inductor omitted from the output stage of the bandpass network. An additional shunt resistor may be placed across the output of the autotransformer to obtain the desired effective load resistance at the input of the autotransformer.

Abstract: Apparatus and method for precisely adjusting the spacing between the phasing plug of a horn type loudspeaker driver and the diaphragm of such loudspeaker. The base of the pole piece is threaded and threadably engages a mating apertured portion of a back plate. A micrometer is employed to adjust the height of the phasing plug above the surface of the top back plate by rotating the phasing plug on its threads. In this manner, spacing between the phasing plug and the diaphragm can be precisely set for each assembly.