| 摘要 |
PURPOSE:To improve the reproducing capability with low cost and low frequency by adopting the constitution that right/left power amplifiers are in BTL connection to double woofers only at a low frequency band. CONSTITUTION:Left/right signals are amplifier by power amplifiers 2, 3 through coupling capacitors C1, C2 normally and reproduced from speakers 5, 6 through the coupling capacitors C6, C7, Further, the left/right signals mixed by resistors R1, R2, are given to a low-pass filter 1, and only a low frequency band is inputted to a base of a transistor (TR) Q1 through a coupling capacitor C3. In setting resistor R4, R5 equal, the collector output and the emitter of the TR Q1 are inversed in the phase. In applying the output signal to the left/right power amplifiers 2, 3, through coupling capacitors C4, C5, the output voltage between the output terminals is twice in the normal signal and than the woofer 4 is driven by the normal double voltage.
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