How to remove the current sound of a USB speaker plugged into a computer?

Just equipped with a host, installed USB small speakers, USB plug into the host will have "squeak squeak" of the current sound, very dry people. Mute also have! Once pulled out, it's gone. The "squeak" sound changes as the speaker volume changes. With another power supply to the USB speaker power, the audio cable Connection notebook is not the case!

USB speaker, its input end has three lines, one of the left and right channels, a public line, this public line and the negative side of the power supply, called ground.

The computer output signal of the ground and USB negative is not necessarily the same line, because the ground involves digital grounding and analog grounding two concepts, so reflected on the speaker, there will be squeaks such interference signal amplification. Why does a group of power supply have no squeak? Because there is no circuit between the power supply and the signal, even if there is interference signal will not be amplified, so there will be no squeak.

In order to get a pure sound signal, it is necessary to filter out the interference signal, between the signal line and the ground and connect the resistance and capacitance, this is the role.

There is a simple way, the speaker's USB interface without the chassis power supply, that is, the speaker USB Jack found on the charge head, one-step.

There is a more simple way is to buy a USB speaker with degaussing Jack, this is to spend a little money ~