Sony Corporation

Sumitomo Bakelite Company Limited

Masaaki Nishimura

Atsushi Matsuda

Jun Kishigami

Takashi Shibata

A reverberation apparatus includes a signal input terminal to be supplied with an input signal, an operational amplifier having an inverted input terminal, a non-inverted input terminal, and an output terminal. The inverted input terminal is connected to the signal input terminal through an input impedance circuit. The non-inverted input terminal is connected to a reference point, and the output terminal is connected to the reference point through an inductance circuit as a load and a first impedance circuit. A second impedance circuit is connected between the inverted input terminal of the operational amplifier and the connection point between the inductance circuit and the first impedance circuit. In this circuit, the inductance circuit functions as a drive circuit of the reverberation apparatus.

Reverberation apparatus

A reverberation apparatus is formed of bucket brigade delay circuit having its input connected to a signal source. An output of the delay circuit is connected through a spring-type reverberator to one of two inputs of an adder, the other being connected to the signal input. The output of the adder provides the desired reverberation sound. In one embodiment, two series connected delay circuits and reverberators are provided, each connecting to a respective input of a respective adder. The other inputs of each adder are connected to the signal source and the outputs of the respective adders provide separate stereophonic-like left and right channel outputs.

A diaphragm for a loudspeaker includes first and second sheet members between which a core member is sandwiched and secured so that the core member has peripheral edge portions extending between the edges of the sheet members and at which the core member is of relatively low strength. A strip-like edging member, preferably of a thermosetting resin, is secured to the peripheral edge portions of the core member and to the edges of the sheet members for increasing the rigidity of the diaphragm at its periphery and preventing unwanted vibrations thereat. A damper member may be secured to the diaphragm adjacent the edging member for movably securing the diaphragm to a loudspeaker frame.

Peripherally reinforced laminated loudspeaker diaphragm

A loudspeaker having a diaphragm including first and second layers and a core sandwiched between the layers, the core being firmly secured to the inner surface of each layer so as to form a unitary structure therewith, a drive assembly causes the diaphragm to vibrate in accordance with a varying electrical input signal fed thereto, and a support is provided for supporting the diaphragm and drive assembly. The layers are formed of materials through which the velocity of propagation of a longitudinal wave is greater than 5000 m/sec, and the core is formed of materials having a shearing elastic modulus Gco which exceeds the value ##EQU1## WHERE E.sub.f is the longitudinal elasticity of each of the layers,

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Tokyo, Japan

Masaaki Nishimura