Use of wireless microphones requires a special sort of "sound check", one that is very different than what most sound people do during their usual pre show-routine.
Conventional sound checks are designed to let the sound person determine that all sound system components are working, that the performers can hear themselves and that they can hear each other. Finally, the sound tech is able to "tune" the sound system so that it sounds good in the performance space.
All of this applies to wireless mics as well. Determining that they are working, sound good, and can be heard by anyone on stage that needs those inputs in their monitor mix is pretty straightforward and is done much the same as it is done for wired mics.
What lots of sound people forget is that the primary reason the mic is wireless is so that it won't be confined to a single location. That means that a thorough wireless mic sound check requires that the microphone be tested in all the locations where it might be used during the performance.
Sometimes, this test is best performed after the performers have finished their sound check. The sound person needs to have someone take the wireless mic and roam all over the stage (and any other location the performer might appear) to insure that there are no "drop outs". Even high quality wireless microphones can suffer periodic signal failure when a combination of direct and reflected radio waves cancel each other out when they reach the microphone receiver.
If you discover an area where a drop out occurs, a minor reconfiguration of the receiver antennae will usually solve the problem. If no simple fix can be found and the drop out or some other interference continues, it will be necessary for the performer to be warned to stay away from that spot.
Finally, the mic needs to be carried near the main speaker system(s) to determine how close a performer can get before feedback becomes a problem. If the sound person has a good idea where these "off limits" zones occur, then he or she can be ready to lower the mic volume or even mute it if the performer wanders into a danger zone.
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-Jeff Harrison is a sound person and special event producer who lives in works in Chapel Hill, NC. His most recent work includes producing professional school commencement exercises for the University of North Carolina.
He can be contacted at firstname.lastname@example.org
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