Practical circuit using STK3048 and STK6153

Many years ago, I bought a power amplifier made of STK3048+STK6153 in the electronics market. It was 100W and cost 25 yuan, which was very cheap. In fact, it was foreign garbage that was sold to China and reused, but the sound quality was pretty good. Later, when I went to Guangzhou to buy it, I actually saw a finished board for 10 yuan. People who know the goods will know it is a treasure, and people who don’t know the goods will think it is garbage, haha

The thick film integrated circuits STK3048 and STK6153 have impressive sound quality and are very cost-effective. They are especially suitable for beginners and friends who prefer integrated amplifiers.

【Circuit Principle】

(1) Using STK3048 to directly drive complementary high-power tubes. STK3048 has high voltage, wide dynamic range, accurate differential input tube pairing, and constant current source loads for both the common emitter terminal and the output collector terminal, so it has low distortion, high gain, and strong power supply ripple suppression. Using STK3048 to drive high-power tubes not only has superior performance but also saves a lot of pairing and debugging, which is simple and reliable.

Figure 3-38 shows the circuit diagram of using STK3048 to drive power tubes 2N3055 and MJ2955. The circuit is so simple that no component can be missing. R1 and R2 can be directly used on the finished board. After power on, if the tubes are not hot and there are no other abnormalities, you can adjust RP without load to make the voltage drop on R1 and R2 10-13mV. In this way, the static current of VT1 and VT2 is 40-50mA, and they work in Class A and B state. When welding, the decoupling capacitor can be welded to the (8th) foot of the integrated circuit, and the other "ground" terminals are connected here. If the midpoint voltage is greater than 10mV, it can be connected to the servo> circuit (the actual measurement in this article is 30mV). After adjustment, you can connect the speaker to work. When listening, it feels no less inferior to some mid-range machines.

(2) Using LF353 to drive STK6153
STK6153 adopts a fully complementary symmetrical structure, which has the advantages of high speed, low noise, and high power. Since it uses a constant current source bias internally, the state is stable. Its exposed heat sink is electrically insulated from the internal circuit and is easy to use. The circuit is shown in Figure 3-39. The gain of the circuit can be adjusted by appropriately changing the resistance value. Using high-quality CBB capacitors for small-capacity DC-blocking capacitors can improve the sound quality.

This circuit does not need to be debugged. When listening, the treble is surprisingly bright, and even feels a bit exaggerated, but it is very clear and there is no sense of force. Subjective evaluation is that the treble of LM3886 is clearer than TDA1514, and the bounce and texture of the bass are also quite strong, and the listening experience is very good.