Power supply: dual AC15V to 28V (AC needs rectification filter) or plusmn DC18V to 40V, recommended plusmn DC35V. (Note that not double 35V transformer is plusmnDC35V , recommended double 26V / 200W toroidal transformer, rectified voltage about DC double 35V.) Note: Battery can not be used! Transformer power: dual-channel power transformer power should not be less than 200W. Monopower transformer power should not be less than 100W. Power supply rectifier filter: two-channel should not be less than 40,000 uF, rectifier bridge is best for more than 25A. Output power: the maximum output power of 85W. Negative planting: can driver large-scale residential speakers. The product is a channel without rectifier circuit. If want stereo, need two boards Net weight: 30g Radiator: According to the supply voltage, power supply high heat, output power is also large (the product does not include heat sink) Audible noise: None Midpoint voltage: less than lmV Colour: black Material: plastic Size: 50 x 35 x 25mm Package Contents: 2 x Audio Amplifier Board Note: 1C onboard amplifier is , The product is welded, tested good finished 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.