Detailed Description  Operating voltage: 18v-30v Output power: 4*40w / 4*20wFrequency range: 20Hz-20KHzAudio output S/N(signal to noise ratio)A weightedblack wire drawing aluminum alloy panel with four channel amplifier, users do not need to configure the amplifier to meet the high-end large and middle bus, commercial vehicles and tour guides to explain and kara ok singingMC1/MC2 jack for microphone input jacks with power indicator lightreverberation conditioning (ECHO) knob to adjust the microphone sound reverberation depth adjustment knob R / L button is a VCD of the channel selector switch, push the buttons for left and right channels switch use MUTE for the mute button is used to control whether or not to cut off the microphone when the musical accompaniment