Current feedback power amplifier circuit using LM1875

The current-mode power amplifier has a better listening experience. The current-mode power amplifier circuit using the power amplifier integrated circuit LM1875 is shown in Figure 5-20. In the figure , the resistance R3 of the resistor t in series with the speaker BL is very small, and the current flowing through the speaker flows through R3. The sampling feedback voltage generated at both ends is proportional to the output current, and the voltage formed on R3 is sent to the feedback input end of the amplifier through R2, forming a current negative feedback, which increases the output impedance of the amplifier while reducing the damping coefficient of the circuit. In the so-called Joubert network, only C4 is used for lead compensation. Although the setting of R2 prevents the output feedback current from being 100% fed back to the negative input terminal, it does prevent the harmful effects of large feedback amounts on the input terminal; at the same time, t also balances the bias of the positive and negative input terminals, eliminating the bias of the output terminal. DC offset.     First, solder two small 0.22 r-JI;F capacitors on feet ③ and ⑤, and solder their other ends together as the grounding resistance of ground terminal 6. They are both bent and soldered at this point. The ±24V power line and output line are directly soldered to the relevant pins. Short-circuit the input end to ground. Weld an ion resistor to the position of the BL speaker. Power on and test the voltage 9 of the output end to ground. If it is less than 100rnV and there is basically no voltage after half an hour. Offset, you can disconnect the input short-circuit and connect the speaker .