| 摘要 |
PROBLEM TO BE SOLVED: To provide an "amplifier and a speaker system having the same" for suppressing a deterioration in the conversion efficiency of a class D amplifier while securing volume regardless of a low output. SOLUTION: The amplifier has a preamplifier 121 for switching scale factors of a gain to a power amplifier 122 in accordance with a volume level to an audio source, and a switching circuit 123 for entirely switching a connection form of at least two voice coils 131 the all impedances of which are identical to either series or parallel in accordance with the volume level. COPYRIGHT: (C)2009,JPO&INPIT
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