Tube power amplifier driven by NE553201

The power amplifier circuit of this machine is shown in Figure 2-16, and the power circuit is shown in Figure 2-17. The circuit principle will not be described in detail. The filament
6.3V voltage is obtained after being stabilized by LM317T, and can also be connected as shown in Figure 2-18 The constant current source circuit shown
is beneficial to extending the life of the filament, but debugging is a little troublesome. R is about 1.5fl. When making the coupling capacitor, be sure to use high-quality CBB capacitors
or tantalum electrolytic capacitors. The resistors , except those indicating the power, use 0.25W metal film resistors D.