Quasi-Class A HI-FI amplifier with excellent performance

STK 3048 and: STK 615 3 are thick film integrated circuits with better performance. It is easy to make a power amplifier with superior
performance using it, but its shortcomings cannot be ignored. First of all, STK6153 is a collector output circuit, so the output resistance
is relatively large; secondly, because its internal bias circuit is fixed, its quiescent current cannot be adjusted, which is a bit regretful.
This article has not included it. After some modifications, a set of quasi-Class A HJ-FJ amplifiers with excellent performance was produced. The circuit principle
is shown in Figure 3-43. D
    This machine has no special requirements for components, but it is best to use CBB capacitors (such as Xindak) for coupling capacitors. VD1 and VD2 can be used.
Light-emitting diodes with a voltage drop of 2V, RlZ and R13 can be used. 2~sw carburized resistor for power amplifier. It is worth mentioning that it uses
base current bias and makes some changes to the traditional connection method of ST K6153, changing it to a circuit with emitter output. The production and debugging of the rate circuit
is relatively simple. You only need to slightly adjust VR1 and VRZ. The final quiescent
current can be adjusted according to different personal preferences. Generally, it is appropriate to adjust it to 100mA, and then replace it with two fixed resistors . But lastly, measure the midpoint potential.
It should generally be below ImV. If it is not too messy during production, you can also directly modify it on the original circuit board, but it is best to
design printed board, which not only resists interference but also has good protection against interference. benefits and will be more beautiful.