With bass and treble tone independent control, this powerful Bluetooth Amplifier has AM interference and filtering function that makes the board THD as low as 0.1% even when working for a long time at large power output, while bringing you clear and round sound. The board features DC9-24V power supply, AUX+Bluetooth 5.0 audio input, and 50W output power. It has 3 adjustable knobs that are used to power on/off and control the main volume, bass, and treble. This product works well with 4-8Ω, 15W-100W passive speakers. You can connect it to Raspberry Pi, mobile phones, and other main-controllers with Bluetooth to DIY your projects.

The Bluetooth Amplifier board comes with bottom/top protective panels and supports protection mechanisms including over-voltage, under-voltage, overheating, short-circuit protection, and DC detection.

Specifications:

Power Supply: 9-24V/2A above
Input: AUX+Bluetooth 5.0
Output Power: 50Wx2
Compatible Speaker: 15W-100W, 4Ω-8Ω
Channel: left/right channel (Stereo)
Bluetooth Transmission Distance: 10m (Without any obstacle)
Protection Mechanism: over-voltage, under-voltage, overheating, short-circuit protection, and DC detection

Note:

The board will output adequate power only when the audio input and power source voltage/current are sufficient. The higher the power supply voltage, the larger the output power. Besides that, speaker impedance also changes the amplifier board power output. Please note that in the case of enough voltage and current, the larger the speaker impedance in ohms, the smaller the output power.
When adjusting treble and bass sound: when the TRBLE or BASS sounds are right-rotated to near maximum, if the sound is distorted, it means that the gain of the Bass/Treble sound is too large. Now you have to turn the TRBLE or BASS knob to the left to lower the gain or rotate the MAIN-VOLUME Knob on the right to the left to reduce the overall volume.

Warranty: 90 days