Production of electron tube + field effect tube power amplifier

This article introduces a tube ten field effect old power amplifier circuit. The self-made gallstone hybrid power amplifier
    is shown in Figure 2-21. The circuit’s front-stage voltage amplification uses three double triode vacuum tubes, one 6N9 and two 6N8.
Its parameters and replacement models are shown in Table 2-4. The final stage adopts a Class A OdB power amplifier without large loop negative feedback, which has minimal distortion and
extremely high resolution. The original circuit power amplifier tubes used K135/J 50 field effect complementary tubes. Because these tubes are currently very expensive and not easily
available, we now use Japanese field effect tubes with almost the same characteristic parameter curves and which are easily available. K1058/J16 2, the parameters of these two tubes
are as shown in the table