NE5532 making headphone amplifier circuit diagram

Single chip microcomputer STM32L151CCU6

Filter 18.432M

In order to listen to the CD with headphones for more than 30 yuan, I installed a high-fidelity headphone amplifier with beautiful sound quality. The NE5532 is generally used as a preamplifier with excellent performance. Now used as a low power amplifier, what is the effect? Rough look at the circuit schematic, almost the same as the general op amp circuit, but the resistance and capacitance have a large change, the working state is different from the op amp circuit. The experiment proves that the NE5532 is a low-power amplifier with excellent performance. Beginners may wish to give it a try.

The following points should be noted during the trial production process:
1, the power filter capacitor C9, C10 used too small will cause self-excitation. It is sufficient to use 100μF for C9 and C10 for preamplification, but it must be increased to 470μF or more for power amplifier. At the same time, the filter capacitor is directly related to the sound quality.
2. The resistance of R4 (R9) and R5 (R10) in the circuit should be debugged repeatedly. In the preamplifier circuit, R4 (R9) is generally 1KΩ, and R5 (R10) is 100KΩ, so that its magnification can be 100 times. But now as a power amplifier, there will be self-excitation, so R4 (R9) is changed to 8.2K, R5 (R10) is reduced to 33K, the magnification is only 4 times, the circuit will not be self-excited, and the negative feedback is also moderate, the sound quality Soft, clear and transparent. If R5 (R10) continues to decrease to 15K, the negative feedback is too deep, not only the volume becomes lighter, the tone is dull, and the reader can repeat debugging to achieve perfection.
3, C2 (C6) is the grounding path of the input loop. In the preamplifier circuit, there is only 10μF. When the amplifier is used as a power amplifier, the input impedance is too large, the signal is blocked, causing distortion or even self-excitation. Now C2 (C6) is increased to 100μF, the sound quality is obviously improved, the sound range is widened, the treble is crisp and sweet, the midrange is pure and bright, and the bass is deep and rich.
4. The power of this unit can be selected from 3V to 15V. It can be connected in two directions (positive and negative 3V) with four battery strings. The volume is not much different from that at 12V, but the sound quality is not as good as 12V. It is recommended to use 9V ~ 12V is better.