As many as you want as long as you have a wireless mic system designed for multiple microphones.
Each microphone needs its own frequency to operate and transmit properly. So it is not possible to use two wireless systems on the same frequency in the same venue or to use two wireless microphones with just one receiver. The individual frequency used by each microphone requires a certain amount of space within a particular frequency band. When two wireless systems are used together, the frequencies must be separated by at least .5 MHz. If frequencies are set too close, microphones will compete with each other, and each system will experience noisy interference and/or sound dropouts. As more transmitters and receivers are added to a particular setup, interaction between frequencies increases. So does the potential for signals crossing over one another and creating interference.
More advanced wireless systems offer greater frequency selection, flexibility and the ability to combine more receivers and transmitters to serve more users. Many of these systems offer preconfigured groups of compatible frequencies to accommodate multiple users, as well as software that can scan the most compatible frequencies in any one particular location.
Last update: 06:50 PM Saturday, August 5, 2006