Most of the equipment in the audio system needs electricity. Although the input is AC power from the power grid, all the circuit work requires DC power. Except for the individual battery, it must undergo the process of voltage transformation, rectification and filtering to complete the conversion. Part of the circuit is what we call the power supply.
The power supply has two forms of linear power supply and switching power supply. The linear power supply is directly transformed by a power frequency transformer, so the input and output are completely isolated, or the AC ground and the DC ground are completely isolated. At this time, look from the output end to the input There is no difference in the status of the live wire and the neutral wire at the end. If the output terminal is not grounded, there is no potential difference between the AC and DC power on this side and the ground. In other words, there is no overcurrent when a person touches any position with one hand a feeling of.
As for the switching power supply, due to the lack of optocoupler, the input and output cannot be completely isolated. Now, this problem does not exist. Almost all switching power supplies are designed with optocouplers, and the isolation effect is basically the same as that of linear power supplies.
Therefore, no matter what kind of working mode the power supply adopts in the current audio equipment, the fire zero problem at the input end does not bother us. Of course, for most audio equipment, the fire zero of the plug is actually required. This is mainly from the safety aspect. It is required that the fire wire must be connected in series with a power switch, fuse, etc., but this may be a problem. If the fire wire is alone in the device If the wiring is too long, it will produce some electromagnetic interference. If it is not handled properly, it will affect the weak signal. At this time, it may be a way to exchange the plug fire zero line, but it is not recommended.