Fully symmetrical MOS FET 100W hi-fi amplifier 03

The fully symmetrical OCL circuit is a relatively complete power amplifier at present. It
connects various parts of the circuit such as differential input amplification, excitation, and power output in a complementary and symmetrical form, giving full play to the advantages of PNP and NPN transistors that can work complementaryly.
The full name OCL circuit is more stable than the ordinary OCL circuit. Better fidelity. Now we introduce a circuit that uses
symmetrical complementary MOS FET tubes 2SK405 and 2SJ115 with "tube" machine tone as the output power amplifier circuit.
    Figure 7-10 is the main amplifier circuit part (only one channel is drawn here). As can be seen from the figure, the input is a pair of differential
tubes 2SA798 and 2SC1583. Their emitters have a 24V voltage regulator tube to stabilize the voltage. Followed by a pair of symmetrical drive tubes
VTR3 and VTR4, their e-poles are connected with low-value resistors in series, causing this stage to cause a small amount of negative feedback, which is beneficial to reducing
the transient intermodulation distortion rate (TIM). VT5 and VT6 are a pair of fully symmetrical tubes, used as radiation followers. VT7 is a thermal tube,
which is installed on the radiator together with the power tube. When the temperature of the radiator rises, the b and e poles of VT7 The resistance decreases, causing
the current of the c electrode of VT7 to increase, so the voltage drop between the b and e electrodes decreases, so that the e output voltage of VT5 and VT6 decreases, which reduces the static bias voltage of a pair of power
MOS FETs , thus preventing the power tube from being affected by temperature. rises and the quiescent current increases.