Headphone amplifier circuit diagram based on NE5532

E5532 is generally used as a preamplifier with excellent performance. Now used as a low-power power amplifier, what is the effect? ​​It is almost the same as a general op amp circuit, but the resistors and capacitors have changed greatly, and the working state is different from that of the op amp circuit. Experiments have proven that NE5532 can be used as a low-power amplifier with excellent performance.

In order to listen to CDs (VCDs) with headphones, I only spent more than thirty yuan to install a high-fidelity headphone amplifier with beautiful sound quality. NE5532 is generally used as a preamplifier with excellent performance. Now used as a low-power amplifier, what is the effect?

A quick look at the circuit schematic shows that it is almost the same as a general op amp circuit, but the resistors and capacitors have changed significantly, and the working state is different from that of the op amp circuit. Experiments have proven that NE5532 can be used as 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. If the power supply filter capacitors C9 and C10 are used too small, they will cause self-excitation. When used as a preamplifier, 100μF for C9 and C10 is enough, but when used as a power amplifier, it must be increased to more than 470μF. At the same time, the filter capacitor is directly related to the sound quality.

2. The resistance values ​​of R4 (R9) and R5 (R10) in the circuit should be adjusted repeatedly. In the preamplifier circuit, R4 (R9) is generally 1KΩ, while R5 (R10) is 100KΩ, so its amplification factor can reach 100 times. But now when making a power amplifier, self-excitation will occur, so R4 (R9) is changed to 8.2K, and R5 (R10) is reduced to 33K. The amplification factor is only 4 times, and the circuit will not be self-excited. At the same time, the negative feedback is appropriate and the sound quality is improved. Soft, clear and highly transparent. If R5 (R10) is further reduced to 15K, the negative feedback will be too deep, not only the volume will become lighter, but the tone will be dull. Readers can debug it repeatedly to achieve perfection.

3. C2 (C6) is the ground path of the input circuit. It is only 10μF in the preamplifier circuit. When used as a power amplifier, the input impedance is too large, blocking the signal, causing distortion or even self-excitation. Now increase C2 (C6) to 100μF, the sound quality is significantly improved, the range is broadened, the treble is crisp and sweet, the midrange is pure and bright, and the bass is deep and rich.

4. The power supply of this machine can be selected from 3V~15V. You can use four batteries connected in series to form a bidirectional (positive and negative 3V). The volume is not much different from that of 12V, but the sound quality is not as good as 12V. It is recommended to use 9V~12V.

In addition, the input end is connected in series with R1 (R6) 51K because the volume is too high when listening with headphones. If R1 (R6) is removed, a small speaker of less than 5 inches can be connected, and the listening effect is also very good in front of the desk or at the bedside.