1. The power supply should be 12V and the current should be above 3A. 2. It is best to use a speaker with an impedance of 4 ohms and higher sensitivity. 3. For some sound sources with relatively low signal levels, a preamplifier should be added to achieve the best effect. 4. Be careful not to connect the positive and negative poles in reverse, otherwise the circuit board be burned. Connect the wires and confirm that there is no problem before turning on the power.<br><br>Control mode: knob power supply Voltage: 12V Communication interface: Due to different batches, there may be differences in product appearance and printed text, which not affect use Colour:As Shown Material:PCB+Plastic+Metal<br><br>Package Contents: 1 x Audio amplifier<br><br>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.