An effective way to reduce the sound of AC power supply of small speaker power amplifier
Time:2023-01-29
Views:1377
Some cheap power amplifiers "buzz" when they are turned on, which not only affects the sound quality, but also makes people upset. Here are some treatment methods:
1、 Power supply and grounding point treatment
The filter capacitance of many power amplifiers is too small, and four of them are only 10000 μ F and 0.22 at both ends μ The CBB capacitance of F can not only reduce the AC sound of the power amplifier in static state, but also improve the transient strength and high-frequency resolution of the power amplifier in large dynamic state. Some power amplifiers still have AC buzzing even after the above treatment, which may be due to improper grounding point. Generally, the grounding point should be selected near the filter capacitor and the "one-point grounding method" should be adopted.
2、 Output stage
If the static potential of the output stage deviates from the zero point, there will be a great buzzing noise. At this time, there may be a problem with the zeroing resistance or the output tube. The output point potential of the power amplifier can be carefully adjusted to be below 100mv. If the zero point cannot be adjusted, carefully check whether some components of the power amplifier, such as the tube, are damaged.
3、 Preamplifier
First, short-circuit the input end of the preamplifier to the ground to see if the noise disappears. If the noise disappears, it can be determined that the noise comes from the input signal line, and it can be replaced with a three-core shielded wire. Note that the shielding layer can only be grounded at one end. In addition, the coupling capacitance should be the capacitance with small leakage, such as tantalum capacitance, MKP capacitance, etc., and the volume potentiometer shell should be grounded.
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