Features 1.[Use Of Power Supply] Recommended to use 18V 19V 24V power supply current 5A or more. If 9V 12V or 1A 2A power supply you can also use but the power is small note that when using the volume to the maximum may be distorted affecting the sound quality. 2.[Application] The higher the voltage of the BT amplifier module the higher the current the more output power if you have only 12V 1A so you can use for 3 to 4 inch speakers. If you are 19V 5A or more can easily be used to take 8 to 10 inch speakers. 3.[2 Sound Input] This sound amplifier module has two sound input modes one is BT input one is AUX input BT mode takes precedence. No matter in which mode BT can be connected. Meet your different needs of use and use after assembly. 4.[Mode Use] BT connection is successful is the BT mode support automatic back connection. BT is not connected when AUX is inserted is AUX mode. Note that when using AUX mode you need to confirm that the module's BT connection has been disconnected. 5.[BASS Potentiometer] The BASS potentiometer in the middle of the amplifier receiver board is to control the bass right rotation bass enhancement left rotation bass attenuation. When the potentiometer is in the middle position the bass is not enhanced and not attenuated. 6.[TREBLE Potentiometer] BT amplifier board on the left side of the TREBLE potentiometer is to control the treble right rotation treble enhancement left rotation treble attenuation. When the potentiometer is in the middle position the treble is not enhanced and not attenuated. Specification Item Type: BT Amplifier ModuleMaterial: PCBProduct Model: ZK 502TBT Version: 5.0 (Unobstructed 10m/32.8ft)SNR: >90dBInput Mode: AUX BTNumber of Channels: Left and Right Dual Channel (Stereo)Amplifier Chip: TPA3116D2 (With AM Interference Suppression Function)Applicable Speakers: 15-100W 4-8Output Power:15W x 2 at 12V8 30W x 2 at 12V4 20W x 2 at 19V8 40W x 2 at 19V4 30W x 2 at 24V8 50W x 2 at 24V4 Package List 1 x BTAmplifierModule2 x Housing1 x Heat Sink Block4 x Studs4 x Screw Post9 x Screw1 x DC Cable1 x Screwdriver Note In the case of sufficient sound input the supply voltage or current is sufficient to have sufficient output power. The higher the power supply voltage the greater the output power the smaller the speaker impedance the greater the output power. Please ensure that the power adapter power is greater than the actual working power of the amplifier.