| 摘要 |
PURPOSE:To make it possible to utilize a low-power and small-size attenuator and reduce the cost considerably by making it possible that sound volume adjustment of an acoustic unit can be performed in the input part. CONSTITUTION:Speaker LF is provided between output terminals P5 and P6 of power IC, and speaker RF is provided between output terminals P5' and P6' of power IC'. Speaker LB is provided between terminals P5 and P5', and speaker RB is provided between terminals P6 and P6'. Meanwhile, left channel input signal L is applied to input terminal P1 of IC, and amplification pathes 2a and 1a are used as a positive-phase amplification output circuit. Right channel input signal R is applied to input terminal P4' of IC', and amplification pathes 2b' and 1b' are used as a reverse-phase amplification output circuit. Input signals are applied to inputs of the other amplification pathes 2b and 1b of IC and 2a' and 1a' of IC' through fader controlling attenuators VR1-VR4, and attenuators VR1 and VR4 and attenuators VR2 and VR3 are so interlocked with each other respectively so that their attenuation quantities are opposite to each other respectively. As the result, sound volume adjustment can be performed in the input side. |
