Saiyin Wireless Microphones,UHF Dual Handheld Dynamic Mic Karaoke System with Rechargeable Microphones and Receiver NOTE : Please turn down the volume of MIC input on your speaker or amp to the lowest before plugging the receiver,and then turn on the mic, turn on the receiver, then turn up the MIC input volume slowly to avoid speaker screeching or damage to amplifier. QUICK TROUBLESHOOTING 1. Make sure the microphones and receiver have enough power; 2. Plug the receiver into a MIC input, not other interfaces; 3. Turn off the microphones and receiver, and then turn on to repair How to repair: turn off the mics and receiver and turn on again, make sure two mics are at different Channels and Frequencies. Frequency Range: CH A: 903-915MHz for microphone A, and CH B: 916-927MHz for microphone B, when the green light on receiver stops flashing, they are connected successfully. Wide Compatibility This wireless microphone system comes with a 6.35mm to 3.5mm converter, making it accommodate more devices like amplifiers, PA system, karaoke machine and powered speakers etc and good for occasions like conference,speech, Web podcast,YouTube recording, Outdoor recording, Yoga instructor, church,Family party, Opening Ceremony, dancing instructor, Promotion, game etc. How to adjust frequencies to avoid interference if two or more microphones are used at the same time? Put the battery into microphone and it turns on automatically. Long press the button "Frequency", when "CH B" flashes, immediately press " + "or"—" to switch to "CH A". Press the button "Frequency" to confirm switching, and press button"Frequency" to adjust frequencies. Do the same for another microphone, make sure microphone A is at CH A frequency, and microphone B is at CH B frequency. If 3 or more microphones are used at the same time, make sure each microphone at different frequencies to avoid any interference. Turn on the receiver (the green light is flashing ), plug in the MIC jack, when receiver connects to the microphones successfully the green light will be always on. Long Working Time Built with three rechargeable and replaceable 1500mAh batteries Two USB charging cables included allowing for mic and receiver charging at the same time Charge for 3-4 hours, and they run for approximately 10 hours Plug and Play The dynamic microphones and receiver pairs automatically once are on power Adjustable Frequency Range: CH A: 903-915MHz, CH B: 916-927MHz Not compatible with Bluetooth speakers, MacBooks and phones Plug in mic jack, not aux jack, otherwise no sound can be heard. Up to 200 ft Transmission Range Updated UHF microphones supports transmission distance up to 200feet (60M) without distortion or loss of sound stable signal, no delay, no radiation, anti-howling, anti-jamming distortion <0.1% and adjustable frequencies Read more