Power amplifier for home theater

This machine uses 6P3P electronic tubes as the power amplifier , and 6N1 as the inverter and preamplifier. In order to meet the needs of ordinary audiophiles,
the output transformer uses a Japanese-shaped iron core and a shield. In this way, it does not affect the frequency response and greatly reduces the cost. , because the power of this machine
is dual 25W, it is very suitable for the needs of ordinary families and small dance halls.
    The circuit of this machine is shown in Figure lo-lo. The power amplifier works in push-pull mode, vi is the preamplifier, and V2 is the inverting stage. When the voltage of the 6P3P plate of the power
amplifier tube is 350V, the output power can reach more than 25W. Due to its strong overload capability, its volume and sound quality
are better than those of transistor low amplifiers, and its nonlinear distortion is small. In order to make the right P3P reach the best working condition, R9 can be adjusted so that
the cathode voltage is 13~15V and the screen current is 65~70mA.
    In terms of structure, the bottom plate is made of 1.2mm thick high-quality iron plate, galvanized and purified in five colors (it is not suitable to use aluminum plate because
the aluminum plate is light and can easily cause machine vibration). 6 Inputs, outputs and key parts are all covered with self-adhesive stickers. Face markings. Output transformer and power
supply The transformers are arranged side by side at the back end of the base plate, with 6P3P on the left and right sides. All heating elements are on the middle and top of the base plate, which is both beautiful and
scientific. All resistive and capacitive components are mounted on a printed circuit board.