| 摘要 |
PROBLEM TO BE SOLVED: To provide an amplifier for a speaker in which the connecting work of a user is easy, neither noise nor allophone is made and good voice regenerating is possible in relation with an amplifier for the vehicle-mounted speaker which drives the speaker for a sound reproduction and the speaker system constituted using this and to provide a speaker system using this. SOLUTION: The amplifier for the speaker includes an input terminal into which an input voce signal is inputted, a detector which detects DC voltage values superimposed on the input voice signal, and a preamplifier circuit connected with the input terminal and the detector to amplify the input voice signal. The detector gives a gain switching control signal to the preamplifier circuit based on the detected DC voltage values, and the preamplifier circuit receives the gain switching control signal and switches the amplification gain of the preamplifier circuit. COPYRIGHT: (C)2007,JPO&INPIT
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