| 摘要 |
PROBLEM TO BE SOLVED: To provide a control system for a power amplifier where the effect of an external noise in an audio input path can be prevented, the sound volume can be regulated and a WEB remote monitoring and the maintenance service are attained through the use of a general communication means. SOLUTION: The digital/analog conversion power amplifier of this invention is configured such that a received digital audio signal is converted into an analog signal, which is given to a voltage controlled amplifier 14, its output is given to an analog power amplifier A, its output is again received and given to a speaker via a switch 28, the amplifier is provided with means that detect output levels of the voltage controlled amplifier 14, the analog power amplifier A, an output impedance to the speaker and a state of the analog power amplifier, and the detection signals above are transmitted via an interface 32 and a LAN output input terminal 34. The power amplifier receives a sound volume adjustment signal from a remote place and a speaker output ON/OFF signal at the LAN output input terminal 34, gives them to the voltage controlled amplifier 14 and the switch 28 via the interface 32 so that the sound volume adjustment and the ON/OFF of the speaker can be remote-controlled.
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