If the signal presented to the transmitter input is too low, it sits too close to the inherent noise floor of the wireless system. If the signal is too high, it simply clips.
Either way, the resulting poor audio is broadcast to the companion receiver and fed to the sound system as it is. Once broadcast this way, it’s too late; this can’t be corrected downstream. Therefore, it is critical to adjust the input sensitivity correctly. No matter the type of adjustment or resolution, the AF meter is the ticket.
Just like metering on your mixing console, use this meter to adjust correctly. And if you think you’re sound checking a user that is going to get a bit “more zealous” when there is a live audience, leave just a few dB of extra safety headroom below clipping.
Once they are on stage with a live audience, it’s not too easy to get your hands on their transmitter for a gain change! Some systems provide a useful AF meter at the receiver. Some also show this same meter on the transmitter.
Some don’t provide a meter at all, but usually provide at least a clip light at one or both ends of the system. In the latter case, the best the operator can do is increase sensitivity while sound checking until the clip light occasionally lights, and then back down slightly.
Correct AF sensitivity is critical for good sounding wireless audio. Even the best, most reliable wireless link you can find will simply reproduce the audio that is presented to its transmitter. If audible clipping occurs, the transmitter input sensitivity is the first place to check. It may need to be reduced. If excessive, constant background noise is audible, the input sensitivity may need to be increased.
Receiver Output
Wireless receivers typically have an output gain adjustment as well. This is designed to optimize their output level to interface with the downstream device, which is usually a mixing console.
This adjustment is sometimes confused as being related to the radio link’s dynamic range. It is not—this adjustment is only for the output level of the receiver and is unrelated to the AF gain staging of the RF link, which must be set at the transmitter.
Kent Margraves began with a B.S. in Music Business and soon migrated to the other end of the spectrum with a serious passion for audio engineering. Over the past 25 years he has spent time as a staff audio director at two mega churches, worked as worship applications specialist at Sennheiser and Digidesign, and toured the world as a concert front of house engineer. Margraves currently serves the worship technology market at WAVE (wave.us) and continues to mix heavily in several notable worship environments including his home church, Elevation Church, in Charlotte, NC. His mission is simply to lead ministries in achieving their best and most un-distracted worship experience through technical excellence. His specialties are mixing techniques, teaching, and RF system optimization.