Specifications: Product name: Bluetooth digital power amplifier for board 50W*2 Product model: ZK-502L Applicable power supply voltage: 5 ~ 24V (9V/12V/15v18v/24V and other adapters are optional, and high voltage is recommended for large power) Customized horn : 30W ~ 200W, 4 Omega;, 8 Omega; Number of channels: left and right channel (stereo) Bluetooth version: 5.0 Protection mechanism: self-healing overheat protection, self-healing short circuit protection Tip: only when the audio input is sufficient and the voltage power supply/current is sufficient, there may be sufficient output power. The higher the supply voltage, the higher the relative power, and a horn with different impedance will have a different output power. When the voltage and current are sufficient, the larger the horn, the lower the relative sound power. Please note!Supply voltage: 12V ------ 8 Omega; horn/12W (left channel) + 12W (right channel), 4 Omega; horn/20W 20W15V -- - 8 Omega;/18 + 18W, 4 Omega;/more than 30 + 30W19V-8 Omega;/32 + 32W, 4 Omega;/greater than 45 + 45W24V-8 Omega;/38 + 38W , 4 Omega; / more than 50 + 50W Specifications: The potentiometer adjusts the volume through the switch, which is convenient for you to control the volume. It is a perfect choice for DIY speakers. If it is a metal box, you need to remove the Bluetooth antenna. Copper DC connectors are used to withstand high current and no heat. Capacitor 470 uf35v solid-state capacitor ensures energy storage and heat dissipation, and stable power supply is the premise of good sound quality. Free lead DC is compatible with the power interface inputs of this product. Even if you don't have a DC adapter or battery, you can easily connect it. Bluetooth 5.0 version has higher transmission efficiency and longer transmission distance. Precautions for use: The power switch on the board is a standby switch. When the switch is turned off, the machine is in a low power standby state. Completely turn off the power or disconnect the DC plug on the machine for a long time. Package includes: 1 * board power amplifier 1 * DC line