Static eletricity and laviler mics

[CDR]

I am working with a theater group and we are having a major problem with static electricity. The stage curtains seem to be part of the problem, everyone's hair stands on end when they get near them. We have sprayed anti static spray on them with poor results. The static is only picked up on the lavaliers. I am thinking of adding 2 more boundary mics to make a total of 4 and not even using the wireless system. The wireless system seems to be useless at this point. Any suggestions?

[Mr.Si]

sounds like a plan to me. Shotgun mics pointing up from the bottom of the stage may work well too, at the front of the stage at the corners or something.

[CDR]

 

sounds like a plan to me. Shotgun mics pointing up from the bottom of the stage may work well too, at the front of the stage at the corners or something. 

<{POST_SNAPBACK}>

 

Thanks for the reply I forgot to mention that we also have 2 condenser mics suspended above but they do not pick up well, the installer is coming tomorrow to check these. I am hoping to do the entire show with the 2 suspended mics and 4 and possibly 6 boundary mics. I just don't trust the wireless system. One time no static and then out of nowhere it is everywhere.

[Solstace]

Not sure why a curtain in particular should be picking up that much static, unless it's made of nylon or something. Am also not sure why it's only the wireless lav mics that should pick up the interference, unless the static is causing sufficient radio interference to affect the signal being transmitted.

 

Now for some silly questions, but without knowing your situation some may be worth asking to narrow down the problem - a little more detail might help clarify the situation for the rest of us! Or is it just me not understanding the problem?

 

Have you tried earthing the curtain rail? (I'm assuming it's metal, like most I've seen in theatres, halls etc). Have you tried moving the receivers closer to the stage? What make/model are the mics? Have the same mics been used successfully elsewhere? Does the static only get picked up near the curtain/under the rail, or is it all over the stage?

 

Also if I'm thinking straight, if there's no-where for the electricity to go, then even with the best anti-static treatment materials it will still stay there, until someone or something allows the charge to be transmitted to ground. For incidence, anti-static packaging works by holding or transmitting the static charge around the object being protected, rather than through it, which is what would happen otherwise. If the problem is bad enough to make people's hair stand on end, as soon as they get near a particular object, then I'd be wanting to sort the problem rather than continue to find more ways around it.

 

Hope some of this helps

 

C.

 

Thinking about it - despite problems with static coming from the curtain, if the radio mic problem is there one day/show and not the next, I'd be wondering if the interference is entirely radio-based, ie. bad placement of receivers or someone else sufficiently nearby using the same radio frequencies for something...

[bruce]

I was just about to post something similar to Solstace.... what makes you think it's static?

 

It could be RF interference from other radio mics, or maybe even interference from something like a flourescent light! Flourescents can be particularly bad if you have any unbalanced audio lines - are the links from the receivers to the mixer balanced?

 

Bruce.

[griffter]

I can concur with the fluorescent light problem. I Once did a conference in a local theatre where we had severe RF problems all day, we tried every trick in the book and were just getting broadband interfence whatever frequency we changed to. We eventually tracked it down (albeit after the gig!) to the house working lights. They werent usually on for shows but as this was a conference they had them on for the audience to take notes!

 

Another thing which can cause inteference is metallic costumes and jewellery!

[CDR]

I guess the reasoning for the problem being caused by static is the fact that the performers hair standing on end, that may not be the problem. By earthing the curtain I assume you mean grounding it. I am not sure how, as this theater business is all new to me, I only got asked to get involved because of some technical background in computers and I have a small amount of experience with a 7 channel mixer for a church. This is a new system in a new gym/auditorium in a new addition in a school which nobody knows how (or wants to) run. There are about 4 different rows of curtains on the stage, and all feel like they are charged with static, the set designer also is making some scenery out of sheets which will be painted and suspended from rails. The curtains are tied onto metal 1 1/2" pipe rails which can be raised and lowered, how would I ground the curtains that are raised up out of site of the audience?

As far as make and model of the mics I would have to look at them, school is closed this week so no practice I don't know if I can get in until next week. The regulars say that they have always had problems with these mics as far as interference (static or whatever) even when the production was done on the Gym floor. As far as florescent lighting there may be some back stage I will have to check. It seems that after we rubbed down the receivers/transmitters with antistatic sheets they worked well for about 2 hours and then when we added all the extra people for different scenes (mostly kids and from what I have read elsewhere rubber soled shoes create static, how many kids wear sneakers!) the problems got out of hand and we had to turn off the wireless mics. One of the regular cast members told me today that they have tried in the past to adjust the screw on the transmitter to change frequency(?) maybe thats part of the problem. I don't think anybody there really knows much about them. I'm just kind of afraid to use them even if I don't have the problem once who's to say I won't have problems with them during the performances coming up in May.

I like the idea of earthing the curtains just not sure how to do it, but I agree that it needs to be done on all curtains. You would think the installer of all of this stage stuff would be aware of the potential for static.

I can try moving the receivers farther apart and see if that helps but they have been in the same location from the start and sometimes we don't have the problems.

As I was just rereading the comments it occurred to me that many of the cast are volunteer firemen and they may be wearing fire monitors which could be interfering, I will see if they wear them during the practices.

Thanks for all the input, I'm getting a real education on this. Keep the info coming!

[Jim]

I like the idea of earthing the curtains just not sure how to do it, but I agree that it needs to be done on all curtains.

<{POST_SNAPBACK}>

 

I'd get some grounding wire (normal electrical yellow/green) and clip/attach it to each curtain rail then run it to a grounding point somewhere. Seeing as it's not exactly a mains electrical circuit, you can probably just clip it to a cold water pipe somewhere. I doubt you need a proper grounding rod. This isn't that difficult a solution, so you might as well try it.

[TeeJay]

I think it may be worth googling for radio mic usage tips.

 

You should be able to get a good understanding before you get back in the space.

I'm suspecting that a good few of your problems will be part of the set-up and not caused by any static build-up (though that's probably not helping)

Feel free to post how it's all connected and we'll let you know if there are obvious fixes that could help.

 

 

Good luck. Let us know how you get on

 

And welcome to the wonderful world of theatre

[CDR]

I had an opportunity to meet with the sound installer today and we looked at serveral things he is in agreement with the curtains being grounded, so we ran the curtains down to a level that we could check the continuity from the 1 1/2' pipe that the curtains hang from to the cable that suspends them through the pulleys. there was none. So we rubbed off some paint and tested again and now there was continuity so we went through all the pipes that suspend curtains and sanded a bare spot where the chains support the pipe to the cable. There is as of right now without anyone around no static in the curtains or in the sound system! Will have to wait until next week to give it a real try. As for florescent lights there are 2 one on each side of the stage but the sound installer felt that it was a non-issue. He thinks the wireless mic are cheap but that the problem was static related. We did come up with at least 2 better quality wireless mics we will try next week. We may try some directional mics suspended from the top the ones that are there are not directional.

I feel better about it now that we have the curtains grounded, but I won't know until we start practice next week.

Thanks for the input

[Jim]

Few ideas in case you come back still stumped:

 

Switch of all light and sound equipment except for the receivers, mixer and speakers. Empty the hall of people, and cut all lights (definitely including the fluorescents). If it's too dark, use a torch to get around but leave no lights on. Then wonder around and see if you still have problems.

 

Could you confirm what you mean by "static" ? Is it true static (like when you turn a radio dial somewhere there isn't a station) or is it a buzz? If it's not the curtain static problem, it might be an issue with your lights. Dimmers can create horrendous buzz at some levels if on the same power leg as the sound equipment or if light feeds run near by sound signal cables.

[CDR]

The static problem was not present last night! Hopefully it is gone, but the humidity was down also. We also changed the drop mics to directional from bi-directional, which seemed to help. We should have 2 more boundary mics this week as well. Maybe we are on the right track now.

[tadawson]

Typically low humidity will make static problems worse, so it sounds like you are going in the right direction.

 

- Tim

[CDR]

It appears that most if not all the noise problems were static related. Haven't had any problems since we grounded the curtains, just an occasional pop of static from costumes, but I think I can live with that, and with the addition of 2 more boundary mics I can now turn off most of the lavaliers if I need too at times. Thanks for the help.

On with the show!

[Light Console]

Here I go again, dragging up a topic but still..

Similar sort of problem, that was touched on in the above replies, but never more than a mention.

Situation: Chruch with two Audio Technica radio mics on the free 17X.XXX MHz channels (not sure which). Various other mics, some flouresent lights, but not on during a service. Radio mics into DI box to mixing position. Induction loop in use, but recievers located outside of loop. Halogen house lighting at the moment, looking at replacing with "arc" lanterns

Problem: about half an hour into the service, static pops are heard from the lapel mic, normally worn by the Vicar, but others too. My guess is that his robes are causing the static charges.

 

How do we earth the Vicar? I am thinking of installing an earthed metal plate on the lecturn/pulpit, which he can touch from time to time, is this worth a try?