Dual 25W Stereo Audio Power Amplifier 02

The entire circuit consists of two parts - Lisheng power amplifier and rectifier filter power supply .
Figure 5-85 is a stereo audio power amplifier circuit diagram. Only one channel is shown in the figure, and the other channel is
exactly the same. After the audio signal is added to the
4.7k,0 volume potentiometer RP2
from The value is very important. Here , Cl is 0.1V:F, and Ri is 51k,fl to ensure that the ultra-low frequency signal above ZOHZ enters the IC port without loss. In addition, R6 and C3 of the feedback loop are in the entire circuit. A key point that affects the frequency response is that C3 uses a 10Q~220vF tantalum capacitor, so that the turning frequency with R6 is as low as 3Hz or for the same consideration. R4, R6. C3 forms a negative feedback loop, R4 and R6 The ratio of determines the gain of the circuit. The specific value can be obtained from the formula: - 1+R4/R6. Among them, R6 fork, R7 and C4 form a treble boost circuit. The boost frequency is about 3. 3kHz--16kHz, and the boost amount is about is 15dB, which can increase the sound playback transparency. 6 R3, R4 and C5 form a bass boost circuit. The boost frequency is 20~200Hz, focusing on the ultra-low frequency band. The maximum boost amount can reach 20dB, which is used to enhance the strength and volume of the sound playback. b Appropriately increasing the treble and bass during playback can not only improve the sound pool, but also balance the loudness of the entire frequency band, which is suitable for everyone's listening preferences. R5 and C2 form a Joubert network with a turning frequency of about 160kHz. After being connected to the speaker system, it starts to work from above 20kHz, attenuating high-frequency signals to prevent the ultra-high frequency from withdrawing. C6 and C7 are the power supply retreat. The coupling capacitor+ can eliminate the interference noise of the power supply and greatly improve the transient response of the power supply . VD1 and VD2 are used to protect the integrated power amplifier circuit TDA2030A. They have no effect when the circuit is working normally, but if an accident occurs to the circuit, they play Because, in order to improve the reliability of the circuit, VD1 , VD2 is best installed with c8. R8 and RZ form a high-frequency compensation network, which has equal loudness control characteristics and can improve the playback quality of small volumes.