The 2X50W power amplifier with low cost and high sound quality is less than 30 yuan. The machine can be used for up to 600 people in the square. The sound reproduction effect is quite satisfactory. Figure 1 is a circuit diagram. The special place of this figure is to increase the negative current feedback of R4, R5, R6 and C2, which can effectively eliminate the distortion caused by the induced voltage of the speaker voice coil, and further improve the sound quality of the machine. Changing R9 can change the working state of the machine. The R9 value increases the output to the Class A working state, the R9 value becomes smaller and the output is closer to the Class B state, and 43Ω is the Class A and Class B state. The machine selection tube uses a 500-type multimeter to measure the β value of Q5 and Q4 to be close, the β values ​​of Q6 and Q7 are close, and the β values ​​of Q1 and Q2 are close. Q1, Q2, Q5 use domestic N5551, Q3, Q4 with N5401, Q6, Q7 with Darlington tube D1277 (disassembled product 2 yuan one). R6, R14, R15 use 5W porcelain resistors, and other RC components have no special requirements. If the welding is correct, it will work normally, the output power is 50W, and two sets of two channels are formed. With two speakers, it is durable in outdoor use and the sound quality is quite satisfactory. Adapter Ring,Ring Camera Adapter,Lens Adapter,Camera Adapter Shaoxing Shangyu Kenuo Photographic Equipment Factory , https://www.kernelphoto.com
The following is the circuit diagram of [Amplifier schematic circuit diagram ] 
November 09, 2022