AMPLIFIER WITH SPEAKER, AND HANDS-FREE DEVICE OF CELLULAR PHONE

PROBLEM TO BE SOLVED: To suppress generation of an echo phenomenon in a telephone set of a telephone call partner even if a cellular phone is a model provided with an exclusive terminal for an earphone instead of a combination terminal for an earphone and a microphone. SOLUTION: This amplifier with a speaker is provided with: an external connection terminal 31 to which the cellular phone and audio equipment are selectively connected via a connection cable 7; a signal processing circuit 4 which includes an amplifier circuit 41 which amplifies a voice reception signal in the cellular phone fetched through the external connection terminal 31 or an audio signal to be output by the audio equipment; and the speaker 40 which converts amplified output by the amplifying circuit 41 into sound to output the converted sound. The signal processing circuit 4 includes: a filter circuit 5 which regulates passage of low frequency components included in the signal fetched by the external connection terminal 31; and a control circuit 6 which controls a degree of regulation of the passing of the low frequency components in the filter circuit 5 according to size of the amplified output by the amplifying circuit 41. COPYRIGHT: (C)2011,JPO&INPIT