If used in a vehicle, the speaker is powered by the vehicle battery. If used in a building, you need a 120v AC to 12v DC power supply with at least a 1.5 amp output, preferably 2 amps. You would have to wire an adapter to use with a wall wart. Most wall warts don't supply enough current. The easiest thing to do is to get a power supply with screw terminals to connect to the speaker power cable. If the power supply has as high as a 13.8 volt output, that is OK. You will normally get about 13.8 volts across the battery in a vehicle when the battery is charging.