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