Headphone Amplifier

This circuit uses 6N1 as preamplifier and 6S6 as power amplifier, so
the anode DC voltage is selected around 270V and connected by the front stage.
It is best to use 523P or two 624 as the rectifier device of the power supply , which has better effect. As
for the filament voltage, first of all, it is necessary to ensure that the characteristics of the two channels
are consistent. It is hoped that the front and rear stages of the two channels can be powered independently. The principle of the symplectic circuit
is shown in Figure 1-30.
    The front stage of 6N1 is connected to AC negative feedback, so the gain of the circuit
is large, about 30 times ÷