Notice: This power amplifier board is pure bass output(Subwoofer), no midrange and treble output. (In order to obtain a larger power, it is recommended that the power supply be not lower than 9V.)Power supply: DC6.5-15V (depending on the required output power), eg. power adapter, switching power supply, battery, etc., the recommended current is more than 3A. Power input interface: 5.5*2.1DC socket or pad of welding wire; Audio input interface: 3.5mm plug or pad of welding wire.Test Data: Output power: VDD = 7.4V RL = 2 Ω 12.5W; Output power: VDD = 9.0V RL= 2 Ω 18W; Output power: VDD = 12V RL = 4 Ω 20W; Output power: VDD = 16V RL= 4 Ω 32W.In order to obtain a more shocking effect, it is recommended to use a 4-5 inch, 4-6Ω 20-50W subwoofer speaker. Upper crossover point: 110Hz.PCB material: FR-4 glass fiber board, thickness: 1.6mm. Onboard fixing hole diameter: M3; Board size: 1.57x1.65x0.78inch (LxWxH), excluding potentiometer handle length (Pot. protruding length 0.59inch).The potentiometer mounting hole diameter needs to be 0.28inch/7mm.