The subwoofer must be matched , and then installed into to make the phase inversion hole. Other parts shall be sealed. Pay more attention to the speaker impedance, mouth meridian and height. If the impedance and mouth meridian are not with note stroke, it will not be enough. Not only the sound is small, but also there is no shaking of the subwoofer The board is compared with the following two speakers, both of which are 4 Euro: the sound on the left is also 4 euro, which is not only very small, but also very poor sound quality; on the right performs very in all aspects This product can drive 5V / 20W (W), based on the principle of circuit, the secondary development and processing, the maximum can be configured to 20W [10W + 10W sub box (5W * 2)]; so the amplifier board has strict requirements for supply and horn, supply mode and horn A. 5V / 3A is inserted into the red socket; Horn requirements: Left and right channel sub box horn: 4 ohm / 5W full frequency horn. speaker: 4 (ohm) 10W-15W speaker. Never a 6-ohm or 8-ohm speaker; B. if the is supplied from the USB socket of the motherboard (5v3a), the USB here can't be charged, please note; Horn requirements: Left and right channel speakers: 4 ohm / 3W full frequency speakers. speaker: 4 (ohm) 5W speaker. Never a 6-euro or 8-euro speaker; Audio source: MP3, MP4, computer, PC, mobile phone Colour:As shown Material:PC+Metal Package Contents: 1 x Amplifier Board Only the above package content, other products are not included. Note: Light reflection and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.