The potentiometer adjusts the volume with a switch for easy volume control, making it perfect for DIY speakers. If it is a metal box, you will need to remove the Bluetooth antenna.The copper contact is used to withstand high current and no heat.Capacitor 470uf35V solid capacitors energy storage and heat dissipation, and stable power supply is a prerequisite for good sound quality.Free DC mains lead, compatible with the input power interface of this product, even if you dont have a DC mains adapter or battery, it can be connected.5.0 Bluetooth version, the transmission efficiency is higher, the transmission distance is longer.Precautions for use The power switch on the board is the standby switch. When the power switch is off, the machine is in a standby mode with low power consumption. To turn off the power completely or unplug the DC plug of the machine for a long time.Questions and answers1. How to choose a power supplyThe power supply with the board is crucial. The higher the voltage, the higher the current, and the better the output power. If you only have 12V 1A, you can bring a 34 inch speaker. If you are 19V 5A or higher, there is no problem with 810 inches, and the power supply must be valued highly. If the voltage is too low, the sound will be distorted after the sound is amplified. If the current is too small, the speaker will draw the voltage low, work abnormally, or the sound quality will deteriorate.It is recommended to use 18V19V24V power supply with current above 3A. If you only have 9V12V or 1A 2A power supply, it can also be used, but the power is small. Please pay attention to the maximum volume when using it, which may affect the sound quality.2. How to choose a speakerCommonly used speakers are generally 8 ohms, can not distinguish between positive and negative, the effect is the same, 4 ohm speakers can also be used.Color blackMaterial plasticSize 553817mmPackage contents1amplifier board with DC cableOnly the above package contents, other products are not included.Note Light and different displays may cause the color of the item in the picture to be slightly different from the real thing. The allowable measurement error is13 cm.