Input stage with bias current introduced by positive power supply

Use the circuit form as shown in Figure 1-35 (a), that is, keep
Ri = R plate, the left tube introduces a bias current from the power supply v+, and the potentiometer
RP adjusts the magnitude of the bias current. This ensures that
the base input resistance of the left tube will not decrease, and
the bias current of the left tube can be adjusted through RP. For example: Japan's Pioneer M22K
has this circuit structure , as shown in Figure 1-35 (b) o