AMPLIFIER WITH SPEAKER, AND HANDSFREE DEVICE OF CELLULAR PHONE

PROBLEM TO BE SOLVED: To output the voice of a communicating party from a speaker, to amplify audio signals outputted by a small-sized and small-output audio device in order to output them from the speaker. SOLUTION: The amplifier with the speaker comprises: an external connection terminal to which a cellular phone 2 and the audio device 3 are selectively connected; a signal processing circuit 4 including an amplifier circuit 41 for amplifying voice reception signals in the cellular phone 2 or audio signals outputted by the audio device 3 fetched from the external connection terminal; and the speaker 40 for converting amplified output by the amplifier 41 to sound and outputting it. The signal processing circuit 4 includes: a low frequency filtering circuit 5 for filtering low-pitched sound by cutting the low frequency components of signals fetched from the external connection terminal; and a control circuit 6 for activating the low frequency filtering circuit 5 when the cellular phone 2 is connected to the external connection terminal and inactivating the low frequency filtering circuit 5 when the audio device 3 is connected to the external connection terminal. COPYRIGHT: (C)2008,JPO&INPIT