ZK-502L MINI Bluetooth 50 DC 5-24V Wireless Audio Digital Power amplifier Stereo board 50Wx2 Bluetooth Amp Amplificador note! The outer casing is a material package, which needs to be purchased separately. It needs to be assembled by itself, and the material package is given a screwdriver. The potentiometer adjusts the volume with a switch for easy control of the volume, making it ideal for DIY speakers.If it is a metal box, you need to bring out the Bluetooth antenna. The copper DC connector is used to withstand high current and no heat. Capacitor 470uf35V solid capacitors ensure power storage and heat dissipation, and stable power supply is a prerequisite for good sound quality. Free DC head lead, compatible with the input power interface of this product, even if you don't have a DC head adapter or battery, it can be easily wired. 5.0 Bluetooth version, the transmission efficiency is higher, the transmission distance is farther. Precautions for use: The power switch on the board is the standby switch. After the switch is turned off, the machine is in a low-power standby state. To completely turn off the power or unplug the DC plug on the machine for a long time. Question and answer: 1. How to choose a power supply? The power supply with the board is critical. The higher the voltage, the higher the current and the better the output power. If you only have 12V 1A, you can bring a 3-4 inch speaker. If you are 19V 5A or above, there is no problem with 8-10 inches, and the power supply must be highly valued. 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 pull 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 speaker? Commonly 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. If your speaker power is small, it may be used between 10W-30W. The power supply voltage is small to prevent the amplifier from burning out after burning. For example, select a power supply below 15V. If you are a 50W-200w speaker, don't worry about the speaker burnout. You can choose 12-24V power supply. The higher the voltage you choose, the louder the output sound or power. 3. How to connect to Bluetooth? Power on the power amplifier, connect the speaker, turn the audio knob blue light to turn on, turn on the phone settings - Bluetooth - search for "BT-WUZHI", and then click the connection, there will be a beep when the connection is successful, this When it is in Bluetooth mode, you can play music. The next time you power on, it will automatically connect with the phone. 4. When the sound becomes louder, the phenomenon of turbid sound appears. The sound is distorted. Please change the adapter power supply with a higher voltage rating. 5. After the sound becomes louder, the sound is stuck. The input power is insufficient, and the power supply itself is intermittently powered off. Please replace the power supply with a larger power. Or the output power is too large, the power amplifier board is seriously heated, and thermal protection occurs, reducing power usage or enhancing heat dissipation. _x000D_