当今各类袖珍收音机、放音机被广泛应用。但是这些机子绝大部分音质差,噪声大。究其根源,大都大于功放输入部分的电路。笔者给许多人改装机子时发现,收音机类无一例外都是因为耦合电容选得太小,而去加重电容选得过大,因此只有中音频部分的信号进入功放。增大耦合电容同时减小去加重电容对频响有所改善,但由于放大器在其频带内对中音频信号的放 Today, all kinds of pocket radio, radio is widely used. However, most of these machines bad sound quality, noise. The root causes, mostly larger than the power amplifier input circuit. When I modified a lot of machines for many people, I noticed that the radios were all selected because the coupling capacitors were too small, while the extra capacitances were too large. Therefore, only the signals in the middle audio part went into the amplifier. Increasing the coupling capacitance while decreasing the decaying capacitance improves the frequency response, but as the amplifier puts the middle audio signal in its band