The “ringing out” of wireless microphones, from what I understand, is a bit of a controversial subject. On the one hand, it’s widely considered an essential part of an audio engineer’s repertoire of skills. There are many instances in which shows simply could not happen without first ringing out the wireless mics sometime during tech week. However, the process can have some serious negative consequences when done incorrectly or carelessly, and it should not be treated as the first line of defense against feedback. Herewith, I’ll talk a bit about feedback in general, followed by why and how I prepare for ringing out microphones.

Feedback (specifically acoustic feedback) occurs when something put out by a speaker is picked up by a microphone and amplified over and over again. In through the mic, out through the speaker, in through the mic… ad infinitum. The frequency at which this occurs determines the frequency that is produced, which we then perceive as feedback. There’s a great article available on the Shure blog that thoroughly explains these concepts, and offers several methods of “fighting the feed,” if you will. I highly encourage giving it a read. Most everyone knows what it sounds like, and many an audio engineer mixes with a constant fear of acoustic feedback.

With that being said, I feel it vital to stress that properly ringing out the microphones is not going to guarantee that one won’t encounter feedback during a show. The process is one of many things that can contribute to an overall reduction in feedback, but is by no means the be-all and end-all of feedback reduction. However, when combined with a treated space, careful compression at specific frequencies, and vigilant mixing, it provides one with an impressive amount of additional headroom, or gain before feedback (GBF). Results are most prominent when working with several wireless microphones at once–especially in particularly “live” spaces–but can be observed in most any system and setup.

Here’s a short checklist of things that should be done before one begins the process of ringing out microphones:

• Ensure that all wireless packs are sufficiently powered. Partially expended batteries from previous shows or rechargeable batteries are recommended for this process, for obvious reasons.
• Ensure that all of the microphone capsules and cables are functional.
• Ensure that all microphones are spaced out evenly across the frequency band, and that no two microphones occupy the same frequency.
• Ensure that the attenuations on the packs (often found under “sensitivity” in the menu) are consistent across packs of similar make and model. e.g. Hart House runs Sennheiser EW 100 G3 packs at -42dB when taping mics on the cheeks of actors. Adjustments are only made if the mounting location is changed.
• Ensure that gain staging on all of the RF receivers, as well as the console itself, is complete. I’ll be writing my next post about gain staging (although it really should have come first), so it’ll be linked below when it’s finished.
• Ensure that the desired EQ on the main mix (or whatever output is being used) is saved. Making changes to individual packs without being cognizant of what’s happening in the graphic EQ for the main mix could make for a lot of extra work later on, and also be detrimental to the mix! So be sure to EQ the output as close to how it’ll be during the show, and avoid touching messing with it further.
• Ensure that all microphones are patched correctly, and have no compressors or gates applied to their respective channels.

Much of this may seem like common sense / rather boring, but it’s important to create as consistent an environment as possible before ringing out the microphones. The better the baseline, the better the results. Stay tuned for Part 2!