Debra Audio AU400 4 channel wireless microphone system. Mic colour strips may be different. These series products adopt UHF frequency and use the international standard common frequency which can be used in all over the world. Due to the low frequency and many reasons, traditional wireless microphone are usually disturbed by many factors especially by the variety of harmonics which are send off by the CD/DVD/VCD/LD and other any digital equipments. Squelch circuit usually analyse the intensity of the RF frequency channel instead of the noise and the needed signal. Using the low traditional wireless microphones in the complex environment or when the signal of the microphone is weak or the microphone is closured, the squelch circuit may be suddenly opened which can result in the receiver sending out a strong bursts of noises. It’s ideal for church, small DJ stage, birthday, wedding or family party, conference, classrooms, small karaoke nights etc.