Mini digital amplifier board 2*3W Class D why is there noise from the speakers after powering on? Answer: 1, there is a whistling sound, should be the introduction of the audio input line, you should use a shielded cable to do the audio input line, there is also an audio input line do not hang to connect the sound source. 2, or a reason may be a bad power supply some switching power supply interference is very large, resulting in the 3, try to turn down the sound, it may also be that the audio signal input is too large to make the signal to produce a cut limit. Excellent noise suppression, in the absence of input audio, the ear against the speaker can not hear any noise, two-channel stereo, 5V power supply that can be output 3W + 3W power, can be directly driven by the 4Ω, 8Ω small speakers, high output power, energy, good sound quality. Unique Class D digital power board without LC filter, can directly use the computer's USB power supply. Dual panel wiring, proper solution to the wiring caused by the ground potential balance and crosstalk between the channels, ultra-miniature design, can be easily placed in a variety of digital products within a small space, amplification efficiency is super high. All the machine for the whole board welding, welding quality is not hand soldering iron welding can be compared!