Features: brand new and high quality The higher the voltage, the higher the current and the better the output power, it is recommended to use 18V19V24V power supply with current above 3A. Commonly used speakers are generally 4 ohms or 8 ohms, can not distinguish between positive and negative, the effect is the same. Bluetooth-compatible mode is preferred, can be connected in either mode. Bluetooth-compatible mode support automatic connection. The TREBLE potentiometer on the left controls the TREBLE. the right TREBLE enhanced and the left TREBLE attenuated.The sound is distort. Please change the adapter power supply with a higher voltage rating. 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 for protection occurs, reducing power usage or enhancing heat dissipation. Specifications: Material:Metal Model Name: ZK-1002T Bluetooth-compatible Version: 5.0 (no shield, 10 meters) Audio Input: AUX+ Bluetooth-compatible Channel: 2.0 (stereo) Chip Solution: TPA3116D2 (with AM interference suppression) Power Range: DC12-24V/5A above Adapter Speaker: 20W-200W, 4-80 Output Power: 20W x @12V, 8 35W x 2@12V,4 35W x 2@19V,8 60W x 2@19V,4 50W x 2@24V,8 100W x 2@24V,4 Size: Approx. 110x70 mm/4.33x2.76 inches Note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Package includes: 1x Amplifier Board