| 摘要 |
<p>A car radio has its audio signal applied through a power amplifier (3) to a loudspeaker (HP) which is also connected through a two-position switch (6) to a booster amplifier output (5) or to earth when the booster is not required. When the booster is required the switch connects the booster output to the loudspeaker while a second gauged switch connects the amplifier output to the booster input. The two amplifiers then apply opposing phase signals to the two loudspeaker terminals. In a variation the same input signal can be applied to both amplifiers with the booster amplifier then having a negative gain. In a further variation, only a fraction of the output of the amplifier is applied to the booster.</p> |
