Yamaha Corporation

Morito Yamada

Satoshi Suzuki

Yuichi Nagata

Shigenobu Kimura

Mikio Kitano

Kiyoto Kuroiwa

Masao Yoshida

An audio amplifier is provided with: an amplifier circuit; a power supply circuit that generates a plurality of power supply voltages; a power supply relay that selects one of the power supply voltages as the power supply voltage supplied to the amplifier circuit; a switching condition determiner that determines whether the switching condition of the power supply relay is satisfied; a silent section detector that detects a silent section of the audio signal which is equal to or greater than the operation time of the power supply relay; and a switching instruction unit for providing the power supply relay with an instruction for switching the power supply voltage during the silent section when the switching condition is satisfied and the silent section is detected.

Audio amplifier and power supply voltage switching method

In an echo effector for imparting an echo effect to an audio signal based on values of a plurality of parameters, a memory is provided for memorizing an interrelationship among the plurality of the parameters which are mutually related to each other. A dial is actuated for independently setting one or more of the parameters to desired values. A microcomputer dependently sets the remaining parameters to appropriate values according to the desired values and the memorized interrelationship. Further, in a sound field effector operative according to a selected program for creating an effect simulative of a sound field in matching with a room situation under which the effector is installed, a program memory stores a plurality of programs which can be selected in terms of types of sound fields and types of room situations. A first switch is operated for designating a desired type of a sound field. A second switch is operated for designating a desired type of a room situation. One program is selected from the program memory according to both of the designated type of the sound field and the designated type of the room situation.

Effector with integral setting of control parameters and adaptive

In an apparatus for amplifying a sound while suppressing a howling noise, a microphone collects a sound and converts the collected sound into a corresponding input signal. An amplifier amplifies the input signal to generate the sound through a loudspeaker. A plurality of equalizers are interposed between the microphone and the amplifier, each equalizer having a variable attenuation frequency for attenuatively filtering the input signal around the attenuation frequency. Detection is conducted for detecting a plurality of noise spectrum peaks of the howling noise contained in the collected sound. Then, an adjustment is conducted adjusting respective variable attenuation frequencies of the plurality of the equalizers correspondingly to the plurality of the detected noise spectrum peaks to thereby remove the howling noise from the generated sound.

Howling remover composed of adjustable equalizers for attenuating

A howling prevention apparatus prevents a howling noise which is generated in a sound amplification system using a microphone and a loudspeaker. The howling prevention apparatus utilizes a plural number of first to n-th equalizers, which have a variable frequency response and which modulate an output of the microphone. A detector detects a frequency point at which a loop gain of the system reaches a peak while supplying a standard noise signal to the loudspeaker to produce a test sound and measuring the sound collected by the microphone through the series of the equalizers. A frequency response of the first equalizer is adjusted to suppress a noise peak at and around a frequency point detected by the detector. Then, a frequency response of the second equalizer is also adjusted to suppress a noise peak at and around another frequency point detected by the detector. Lastly, a frequency response of the n-th equalizer is adjusted by subsequently repeating the above setting procedure.

Howling remover having cascade connected equalizers suppressing multiple

A car audio apparatus mounted on an automobile and having a function for preventing theft, the car audio apparatus includes a main body portion fixed to the automobile and a front panel detachably mounted to the main body portion of the audio apparatus. The main body portion has a CPU and a first memory for storing a first secret code and the front panel has a second memory for storing a second secret code. The CPU is capable of respectively reading out the first and second secret codes from the first and second memories and comparing the first secret code with the second secret code so that when both secret codes agree, the CPU enables operation of the car audio apparatus and when both of the secret codes do not agree, the CPU inhibits the operation of the car audio apparatus.

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Hamamatsu, Japan

Morito Yamada