The board uses the PT2399 built-in chip to return to sound processing, and the setting is the four amp field effect opTL074 for audio signal amplification and sound processing.Also added a new 5V output, can be connected to the USB Bluetooth decoder board, more convenient to use.In addition, the karaoke card also uses a two-way microphone input (compatible with electret microphone)Working voltage: Double AC12 ~ 15V Colour: greenMaterial: plasticSize: 157x88mm Package Contents:1 * Microphone Amplifier Tone BoardNOTE:This is the front tuning card of the amplifier. Need to be equipped with a post amplifier to use.If you contact for the first time, you might not understand,This card is set up with a station amplifier and has no audio output. You need to match a post amplifier. Just import the signal from the preamp.Pre-tuning signal-input post-amplifier-post-amplifier pushes signal processing to the speaker Only the above package content, other products are not included.Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.