Notes

1. Please strictly install the wiring diagram

2. Do not connect the power supply in reverse, otherwise the IC will burn out

3. Please use a 2.5-5.5V DC power supply, not an AC power supply or a power supply higher than 5.5V.

It is recommended to use a DC 5V

4. The power supply current is above 1A

1. Poor power supply filtering is caused by AC ripple. Increasing the filter capacitor can basically solve the problem.

2. The sound source itself has noise. It is recommended to use lossless format for sound testing.

3. The signal line is of poor quality or is not a dedicated shielded line.

4. The signal line is poorly released or suspended. If the bottom line of the input end is suspended, the noise will be very loud.

5. The board is installed in a metal shell to shield and avoid interference to a large extent.

6. The shared power supply interferes with each other. The wiring is unreasonable during installation.

1. If the speaker is exposed without a box and plays, the sound will be short-circuited and the sound will be low. If there is no box temporarily, a simple test method is: find a cardboard box, stick it around with adhesive to make a box, dig a big hole that can just hold the speaker, and play with the speaker mouth facing outward for better results.

2. The speaker power, impedance and function do not match. The rated power of the speaker should be greater than or equal to the output power of the amplifier. The impedance is generally selected to be 4-8 ohms. The material and caliber of the speaker's diaphragm are also very important. Please choose according to the specific situation.

3. The input signal level is too low to meet the amplitude required by the amplifier, which should usually be between 600mV and 1V. If it cannot be reached, a preamplifier should be added.
   

Distortion is the phenomenon that the amplitude ratio, phase relationship and waveform shape of the input signal and the output signal change. Audio amplifier distortion is divided into two categories: electrical distortion and physical distortion. Electrical distortion is caused by electricity, and acoustic distortion is caused by the sound reproduction device. There are types of electrical distortion: harmonic distortion, intermodulation distortion, and transient distortion. Acoustic distortion is mainly AC interface distortion. According to its nature, there are nonlinear distortion and linear distortion. Beginners often ignore the following "electrical distortion": If the selected power supply voltage and power are too low, distortion will occur when the volume is turned up. For example, if the peak output power of an amplifier is 15W and the recommended working voltage is 12V, then the power supply power should be about 1.5 times greater than the peak output power of the amplifier, about 22W, that is, current = power/voltage = 22/12 = about 1.8A. Excessive input level amplitude will also cause saturation distortion.