| 摘要 |
PURPOSE:To obtain an optimum reproducing output in accordance with the type of an input source by controlling the output of a control means corresponding to the level of the low frequency band component of a stereo sound signal. CONSTITUTION:The low frequency component of a sound signal L is eliminated by an HPF 2L and outputted by a voltage control amplifier VCA circuit 4L at the degree of amplification in accordance with control voltage V of a control voltage output circuit 3L. Similarly, the low frequency component of a sound signal R is eliminated by an HPF 2R and outputted by a VCL 4R at the degree of amplification in accordance with control coltage V. At the same time, an addition circuit 5 forms a sum signal L+R and extracts only a low frequency component Low via an LPF 6. A control means 7 supplies the output of a control voltage output circuit 3Low to a VCA circuit 4Low via a switch circuit 10 when the output of a rectification circuit 9 exceeds a prescribed value, and makes an output at the corresponding amplification degree. Each output is amplified in electricity and reproduced by a dedicated speaker. Thus, the selection between a 3-D system reproduction capable of obtaining rich low tone sound and a stereo reproduction can be properly made corresponding to the type of the input source with a speaker system having a small diameter. |
