DROK TDA2030A 2.1 Digital Stereo Power Amp Kits 2 Channel Subwoofer Audio Amplifier Circuit Board for DIY Operating voltage: Dual AC 12V (AC 12V-0-12V) Maximum output power: left and right channels 18Wx2, subwoofer 36Wx1 Output Impedance: 4-8 ohms; PCB Dimensions: About 117x60x35mm Potentiometer From left to right as follows: Subwoofer volume, treble adjustment, the total volume. if need the dual 12VAC power supply, please check the item B00EALENL2