2. What should I do if the SP3 BT fails to work?

The output volume is quite small when connecting to mobile phone via Bluetooth?

Please go to the settings of the mobile phone and turn on Bluetooth, then enable the 'Bluetooth volume synchronized with phone volume' option.

When SP3 BT plays subwoofer or big dynamic bass music with bass setting to max, the inverted tube will come out with a poof sound？

This is a normal phenomenon. SP3 BT is a 3.5-inch speakers, the lowest lower frequency limit is 65 Hz. Small-diameter speakers to send out such a low low-frequency requires a greater amplitude of vibration. At extreme power, the volume and the gain are largest. At this time, the forward and backward vibration amplitude of the speaker are also the largest. The air compression ratio in the case is also very large. Therefore, the airflow sound from the inverted phase tube will be larger.

If you feel that the airflow sound is too loud, you can try to lower the gain.

SP3 BT coaxial, optical input has snowflake sound?

This is a normal noise floor sound. The noise floor of the amplifier chip is generally mv level, which is difficult to completely deal with. The SP3 BT circuit processing has limited the noise floor to uV level. But since tweeter sensitivity is relatively high, when listening close to the speaker you will still hear some noise floor sound. When listening at normal distance (30CM outside), the noise is not noticeable.

There are no similar nosie when using USB and Bluetooth input: The amplifier is muted in the Bluetooth channel. But coaxial and optical input channels can not be controlled!

Continuous noise comes from SP3 BT when connecting to the computer or other desktop devices even when no music is not playing? And the noise disappears when it is disconnected from the computer or other device?

This is caused by the ground loop interference of the whole power supply system. The electromagnetic environment of the computer is more complex, there is no way to solve the current design, the only way to disconnect the ground loop of the entire system.

You can try the following methods for help:

1. You can try to connect the 3.5mm port or USB port in the back panel of the computer. The interference and current sound in the rear panel are small but more obvious in the front panel .

2. If it can not be solved, you can try to buy a 2-plug to 3-plug adapter for help