I couldn't quite organize the last entry to describe real, practical mic checks for wireless mics. Hence this one.
IF you get the chance for a proper mic check, this is what you want to have;
The actors should be wearing the mic. Some will try to come out to mic check holding up the microphone with their hand. Send them away until they've taped it on. If the actor has a hat or mask or wig, that should be on the actor as well. If the actor is wearing metallic fabrics, those should be on their bodies.
The first thing to listen to is silence. When the actor isn't speaking, is there hiss? Then you may have the sensitivity too low and the amplification too high. Or a bad transmitter. Do you hear an electrical whine or warbling? Bad transmitter.
If you hear a "whiff" or the sound cuts in and out, put an eye on the RF strength indicators on your receiver and have the actor walk slooooowly around the stage. If you have the time, or you suspect an RF problem anyhow, it is worth having the actor visit every part of the stage they will be using and make sure you get adequate signal strength every where.
If you hear a rustling, crackling, or popping, suspect a bad connection. It might be anywhere in the system, from the pot on the head amp to the jacks in the patch bay, but we're worrying about mic test now. It's probably going to be the element. Have the actor move around. Send an assistant out to the stage and have them tug on the connector, twist the cord, and otherwise jiggle things to see if you can make the sound worse. And send your other assistant for a spare element!
(For stuff like this, it is far better for everyone if you just replace what is on the actor, mark what was on them as suspect, and do your diagnostics later when you don't have a room full of people standing around waiting on you.)
Second thing is voice. Many actors have been trained by many (poor) sound checks and will go straight into belting out a song -- usually off key. I try to have them speak instead. I learn more about the natural timbre of their voice when they speak. In a stage voice, mind you. This is one place where "indoors voice" is never appropriate.
Assuming you previously dialed in the desired sound and placement, you are now listening for two things; that the voice still sounds like it should, and that it is free of new artifacts.
Hollow, flanging sounds can come from hats, from the placement, and from something as simple as the tape slipping over the head of the element.
A heavier, more phlegmatic sound than you expected is almost always an error in placement. Left to their own devices, actors will tape lower and lower on the cheek, and closer and closer to their mouth, as if subconsciously trying to save themselves some of the effort of singing full voice.
An oddly distant and often weirdly tinny sound is often the result of the mic slipping entirely, ending up inside a wig cap or behind an ear.
A thick, wooly, or chocked sound happens when the filter cap needs make-up cleaned off it, and as elements corrode and age. You can often bring a little clarity back to Countryman elements by washing them out in rubbing alcohol -- and making sure they are completely dry before you power them up again. But they will inevitably lose their tone over time, sounding cheap and muffled after a year or two of use.
Most actors have a different sound in their singing voice. It is well worth having them open up. They should be singing at least something similar to a song from the show, and in a register they use often in the show (again, for some peculiar reason actors will chose to do sound check with the one verse they sing falsetto, or in some ultra-peculiar character voice).
Check -- assuming you didn't check before -- that the gain staging is clean and they aren't clipping. And listen as before to make sure the sound like you want them to sound. Be very aware that actors will make mic check before they've warmed up. Also, a significant number of actors can't find their pitch without aid. When they sing a Capella, they will sing in the wrong key (or between keys) and they will find it uncomfortable and strange-feeling, and as a result they won't sound the way they do in the show.
Which brings me to the biggest caution of them all.
Over and over, I've seen this done in mic check. The mixer asks each actor to step to center stage and start singing. Then he adjusts their EQ to sound "right," and adjusts the head amp until everyone doing mic check that day is roughly at the same level.
Yes, you want to EQ. Yes, you want to adjust your head amp so you can put the faders for the ensemble straight across. That way, you always know without consideration of which actor it is where your average dialog and song settings are, and where the faders need to be to achieve a rough vocal blend between several actors at once.
And you should do this the very first mic check you have, because that is the only time you will really have the luxury to listen to just that voice alone.
But just as in mixing, you don't want the perfect sound for that individual instrument. You want the sound that works in the mix.
And, as I said, the actor in mic check isn't doing what the actor in the scene will do. So when you get to their big solo number in full dress rehearsal, well, then you do the final adjustment to zero in their sound. Their EQ, their compressor settings, and of course their gain.
Don't second-guess yourself during mic check. You had the settings right in last night's performance, so don't mess with them! Adjust only that which has changed, or was clearly a mistake. Otherwise, understand that the actor is cold, bored, out of key, and not wearing all the parts of his costume, and two hours later backed by the full back and across the stage from the soprano he is going to sound different.
Be conservative. Use mic check to confirm that everything is working normally. Don't sit there and try to re-write the show.
So what if you can't get a mic check?
First, check the gear before the show. If you have problematic gear, bring each and every mic down to the stage and test them yourself before you hand them out. (This is why us sound engineers don't have day jobs. Our pre-show checks need to start too early in the evening).
Especially if this is the first test of the gear, be thorough. Listen to the silence. Talk into it. Wiggle the cord. Shake the transmitter (best way to discover bad battery clips). Walk around the stage looking for holes in the RF.
At my current space, I do all the check I feel is necessary while I am prepping the mics. When I've got a loose wire, I can see the "clip" light blinking as I stick the condom on the transmitter. I also look for problems in the display, the battery charge, loose connector, or anything else that stands out.
When I get to the board, I check the tell-tales on the receivers. They should have strong and characteristic RF, and show some activity in AF from the general noise of the room. One error that leaps out is if the RF is low but there is a ton of audio. That means the mic isn't working at all, and I'm seeing a television station in the same band.
I love the channel strip meters. I should see the bottom indicator lit. If I clap my hands near the shoe tree where the mics are stored prior to the actors getting them, all of the channel strips should light in about the same amount.
A signal that violently goes to very strong and back to normal, very quickly. is either someone dropping the mic on a counter, or a bad connection. So is a signal that stays at a high level but steady, without moving. And if the signal goes dead, once again we have a dead element or a dead mic.
When the mics are finally on actors, then, I can listen via PFL and make sure the actors sound normal. Unfortunately they are backstage, you are on headphones out in the audience, and there's no way to make them talk or sing on cue. Vocal warm-ups are good for this; if most of the cast is warming up, you can zip through most of your mics and confirm they are being worn correctly and are still working right.
The meter check and the PFL check also take place during the show. Particularly in kids shows, or early in the dress rehearsal process, where you can't be sure who is actually singing and who is still back in the dressing room. I've gotten pretty good at recognizing the difference in sound, and even in how the channel meter strip looks!