Yes. It is true. I strongly dislike our wireless system. There is nasty feedback, we can't find an effing frequency that works properly, when actors move around on stage it cuts in and out. I have no idea what to do about this. I do a fair bit of home recording and I suppose I know a decent bit about theatre audio from close to a year of experience, but I certainly do not know nearly as much as this learned tech/techie/technician community. Community of tech people. Yes. That should avoid controversy.

So, what could be the problem? And what could rectify said problem? We may be getting in touch with some professional people to come in and take a look, but as the sound designer for the play which will need said microphones I would like to know what the heck is going on while these people are here and, if possible, help them out. Or, maybe I could even fix it. But I doubt that.

One problem that we have with our headsets (which are not wireless) is that we pick up portugese television due to pipes that run throughout our school acting as an antenna. Could that be causing interference on our stage? Could it just be that we have crappy mic's? They're Sennheiser, I don't know much about them. I doubt that it's the mics though. We just put on the Laramie Project, and an actress needed a mic for a scene. We used a really nice Shure that our TD's brother gave us/lent to us. It didn't work all that well. It worked even worse for an actress who lost her voice and had to be mic'd for her monologue. It was awful, I felt terrible for her. And, as I was not running the show, I couldn't cut the mic... so the sound op just kept it up while I banged my head against a wall. It was painful. We need to fix our wireless system before February (Wonderful Town), so any advice is GREATLY appreciated.

Thanks so much
Yeah.... feedback is the wrong word. I'm attempting to describe this terrible crackling sound that occurs when the mic cuts in and out. It also pops up when actors are moving. Interference, I'd say.

I'm not sure of the model. Auditions are going on right now, so I can't get into the closet where they're kept to check on that. Shall do so later.


Active Member
Sounds like there is a loose connection before it transmits the wireless signal. If it involves a beltpack make sure that is has a good connection.


Wireless Guy
Premium Member
Yes, we definitely need to know the model of the mics being used. Also, it would be helpful to know how many units you are using, whether there is any antenna distribution (are the antennas on the actual receivers or on a separate antenna thingie), what frequency band the mics operate at (some models have more than one frequency band, such as 662-682 MHz, or 524-542 MHz), and whether you use any other wireless systems in the building (intercoms, radios, in ear monitors, etc). Also, does athletics use any wireless equipment that you know of? Finally, if you are comfortable telling us what your zip code is, we can look up what TV stations might interfere with your wireless mics.


Well-Known Member
Good questions Mike.

I'll add two of my own.

1. Are the receivers line of sight to the stage?

2. Are you using new batteries at every performance?
Yes, we do change the batteries before each performance. The recievers are directly below our apron at the moment, which is not the best place for them. However the is no better place- our booth is full and rather small, and the rest is seating (unless we put the system in the middle of the handicapped seating below the balcony and above the first section of seating and rope it off, which is not very likely nor is very practical at the moment.)

Using four units. Beltpacks. I believe that there are two antennas for the four (one for two). I could be very wrong, though. They're in a roadcase, mounted two on the left, two on the right. Above those are the antennas. The actual antennas on the packs, I don't know if those being slightly bent will cause a huge problem... but, if so, that could do it. Don't really think that they're bent, or that bent if they are. And it would really just sort of twisted, curving one way or another.

I'll check the frequencies tomorrow and get back to you, as well as the model. I don't know if there's much else that's wireless in the building. Cell phones (we live in a rather affluent community, so all of the obnoxious high schoolers who forget to turn freaking cell phones off might create a problem?). I'll check it out though.

School zip code is 02459.


Active Member
Check your mics. How long have you had the microphone units on these packs? They're fragile and they break and when they do, you get lots of cutting in and out. And popping. That's definitely what you need to check, because popping won't occur with transmission cutting in and out, but circuits connecting and disconnecting.
The microphones for wireless pakcs are almost considered an expendable in theater.


Like Jbeutt said, it might be worth it to check for damage. On a few of our wireless mics, a chunk of insulation has come off of the antenna or mic. If the antenna wire is expossed there can be lots of drop outs. If the wire for the actual mic is expossed you can get that horrible crackling sound.


Active Member
Here's a little thing you can do to see if your problem is the radio link or the audio into the transmitter. On all the Sennheiser frequency-agile UHF mics, there's two bar graphs on the receiver. One is for RF level and the other for AF level. Take a quick look at the receiver display when the mics are up to no good. If the RF level is up there and the AF level is peaking with the noise, then it's an audio problem probably with the microphone, the cable, or the transmitter jack or electronics. If the RF level is very low when the noise is occuring, then you have an RF link problem. Try taking the antennas out of the road case (if they already aren't), or adding an RF preamp in between the antenna and receiver. You can also buy directional antennas that offer more gain in a certain direction. Just pointing them at the stage gives you lots more signal level than the omnidirectional antennas provided with the receivers. And it's also a good way to reduce interference, provided the source of the interference is not radiating from the direction of the stage. Most moderate-gain directional antennas have a response pattern similar to a supercardoid microphone, to give you a reference point.
I'm not entirely sure how old they are, nor do I know how long the problem has been in existence. I'll find out on monday. At the very least since last February, at most a few years. The auditorium was renovated, sound system was set up three or four years ago. That may be when the mics were purchased. Could be before that, though, since the mics are separate from the main system.


Wireless Guy
Premium Member
Having the mics under the apron should be fine, because the distance between the actors and the receivers should be very low (a good thing). As far as the antennas on the bodypacks being bent, that is normal. If the receiver antennas are bent, however, that might cause some problems. Cell phone interference should be negligible.

It would help to know what frequencies you are transmitting on currently - that is likely the big issue here. I looked at the number of TV stations in and around your area, and it's jam-packed.

As far as good frequencies to use, you might try the following (use one grouping for your mics, depending on the range of frequencies you can select from):

530.5, 532.6, 534.15, 545.5

587.0, 587.425, 588.850, 589.275

656.35, 656.85, 657.575, 658.5

And make sure the transmitter and receiver are on the same frequency! I actually fixed a wireless system for someone that "sounded really tinny." It turned out the transmitter and receiver were on different frequencies, but the receiver was still able to pick up part of the signal. Matching the frequencies up fixed the problem entirely.
I am having a similar issue with our Sennheiser eW100 wireless mics. We are running 12 of them (3 sets of 4 on an antenna splitter). I have the Sennheiser antenna paddles for each antenna splitter that are on a FOH lighting electric and are pointing directly to the stage. Each paddle has an antenna preamp hooked to it. It seems like the ideal setup, but we are still having problems. the actors wear their mics under their costumes because they have to change a lot, so there's not much to do about placement. is it uncommon for actors to wear their mics in front of them as opposed to behind them? Currently they all wear them in the small of their back, but to wear them in the front might be a posssibility. I have tried straightening the antenna's on the transmitters by attaching wire to them to keep them erect. I am at a loss of what to do. I go to Wright State University in Dayton Ohio if that matters for anything. Any help would be greatly appreciated.
They are not popping. I know for a fact that it isnt the physical equipment. The signal itself goes in and out. The mic elements themselves aren't under costumes. They run from the transmitter up their backs and over their ear. I am using Countryman E3 elements.


Well-Known Member
Wireless mic are always going to be unreliable

if you had an option would you really use wireless mic's over wired one



Active Member
May i propose that you move the rack mounted units from the booth to the stage place them on the down stage left or right corner just behind the precinium outside of the road case. the closer they are to any metal object the more interferance you will get unless you use a seperate antena system, and i will take a wild guess that the reason your getting drop outs is either

1 your not in a good line of sight or your just to far away

2 the road case is made of metal and is interfering with the antenas. or the rack rails are doing the same.

the order that i would try just to make your life easier is this

1 remove them from the rack and place them on a table or box made of wood or cardboard and test them

2 if this fails take one unit and place it in the middle of the stage and walk around with a mic if this doesnt work then there is a problem with your system.

to fix your feedback problem get an eq unit and just keep playing till you get it right. there is a program called golden ears that trains your ears to hear all the differnt types of feed back and pink noise etc. get it and train your self.


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