# Headsets...



## TechnicalRunner (Feb 3, 2005)

Hey.....I'm sorry if this is posted somewhere else already....I've been having a lot of trouble with our headsets lately (basically they're all broken except 2 at this point - I just discovered this tonight and we have a show next week), and I was wondering if anyone knows of any good kinds? Thanks!

- Lisa


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## Peter (Feb 3, 2005)

My most recent pair of headphones are sony's MDR-V6000 model. They go for about $100 (high for the cheap end of headphones, low for the good end). They have good over all sound (from my ears), they are not the BEST headphones I have ever heard (but those were THOUSANDS of dolars) but they are certainly not the worst by a long shot. I also like the fact they are very durable. Mine are still in pristine condition even after more then 2 years of heavy use. Talking to a friend from Grove City College (they use the same headphones in their theator), they used to go through at least one pair of headphones a year, but when I talked to him these had been in their third year and were still in decent shape. 

I am sure others will have their suggestions too, but that's just my experience. 

If you dont mind, can I expand on the question asked here too? What would people suggest for good noise canceling headphones? Is it practical to use them to aid in recording a live concert (to help block out the outside sound and just hear what you are recording)?


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## Andy_Leviss (Feb 4, 2005)

Well, Lisa said headsets, not headphones. That still leaves the question, however, whether you're talking about ClearCom headsets, or headset microphones, or announcer style headset microphones (ie, headphones with a mic boom). Which do you need? )

As for noise-cancelling, I cannot recommend ANY. They all add artifacts to the sound and are not at all accurate. If noise reduction is a must, you want noise BLOCKING in-ear phones, such as the Shure E-series or those from Etymotic Research.

--Andy


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## bdesmond (Feb 4, 2005)

If you're thinking alogn the lines of Clearrcom headsets, Lisa, I personally like the lightweight one that Clearcom sells for something like $40 SRP I think. I've never used one in a very loud environment (e.g. FOH at a concert) 

There are the skull crushers too, those will probably block some ambient noise out, but, you're going to have less usable volume in your head when you take the things off after a show.


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## Peter (Feb 4, 2005)

ah ok, my bad. I must have read Lisa's post too quickly.


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## ricc0luke (Feb 4, 2005)

Production Intercom- easy to use, lightwieght, never fails.

www.beltpack.com


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## cutlunch (Feb 4, 2005)

TechnicalRunner said:


> Hey.....I'm sorry if this is posted somewhere else already....I've been having a lot of trouble with our headsets lately (basically they're all broken except 2 at this point - I just discovered this tonight and we have a show next week), and I was wondering if anyone knows of any good kinds? Thanks!
> 
> - Lisa



There have been posts about buying new headsets but I want to ask is what do you mean by "broken"?

Are they physicaly broken as in someone has snapped off the mike, ear piece etc. or do they just not work. As well as the actual headsets have you tested the beltpacks as also. Sometimes the fault can be in the belt packs eg broken plug etc.

Lisa if you have already done the following please accept my apologies for teaching you to suck eggs. If you haven't it might be worth trying.

If you haven't already I would find a headset that works with a working beltpack. I would then swap that headset for all the other headsets noting the faults on the ones that don't go eg. no sound at all, sound but mike not working etc. This will give you a list that will maybe allow you to swap parts to make up some good ones from the broken bits. I would next confirm using the good headset with all the beltpacks to make sure there is no problem with the beltpacks themselves. Have you checked all the leads that go to the belt packs.

If the headsets look all right you can check the plugs for missing/ damaged pins or disconnected wires. Also check around the earpieces as sometimes those wires can come loose too. If you can solder you could do the repairs else you'll need to find someone else. A multimeter would help to check for open circuits.

Once again my apologies if you have done this already. When you answer posts you don't always know what level that person is at skillwise.


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## TechnicalRunner (Feb 5, 2005)

sorry for the confusion - i was thinking more along this lines of a clearcom type headset. we had ones from radio shack before, and they aren't that old (2 years or something), but people don't store them properly and drop them all the time etc. so they've been pretty beat up. 

- Lisa


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## TechnicalRunner (Feb 5, 2005)

no i haven't check everything about the headsets yet, i didn't really have time the other day (it was a rehearsal and the director decided she wanted a headset with about 5 minutes to go so i was digging around to find some working ones). what i meant by "broken" was some hum when you turn them on, others are just static when someone talks, some don't go on (could be the battery, again i haven't checked all of them yet), and some are apart in hopes of being fixed (someone else took them apart and never finished fixing them). so now we're down to 2 working headsets at them moment. i'm going to try to go in early for our next rehearsal and look at them more closely, but so many of them are apart i think we're going to need some more anyway. 

-Lisa


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## Andy_Leviss (Feb 6, 2005)

IF you're using RadioShack, I'm guessing you're not actually using ClearCom type wired intercoms, but two-way radios with headsets, yes? If so, are you looking to stay with wireless, and if so, what's your budget and is being able to talk simultaneously a need, or are you cool staying with push-to-talk radios?

If you don't want/need wireless, are you actually looking for a ClearCom or other brand party-line wired system?

The headset is only one part of the equation, and literally refers to just the actual headset itself, not the device that allows the user of the headset to actually communicate with anybody else. Without a radio or intercom device of some sort to connect the headset to, it's just a weird fashion accessory!


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## TechnicalRunner (Feb 6, 2005)

yes i'm sorry - we are using 2-way radios with headsets. i'm just looking around for any suggestions of better kinds - i think we should stay with the push-to-talk ones though, sometimes we say things we don't mean  i'm not to familiar with the clearcoms...i've heard of them though. can you elaborate a little bit please?? thanks!

- Lisa


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## TechnicalDirector3-W (Feb 6, 2005)

One great brand of headset is Telex...they make them for many different things, check them out.

www.telex.com


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## Andy_Leviss (Feb 6, 2005)

ClearCom, Telex RTS, and Telex AudioCom are three popular flavors of wired "party line" intercom systems. They use one or more base stations and then beltpacks, with optional wireless beltpacks. You can also add speaker stations, tie into paging systems, etc. 

The various stations are interconnected using standard XLR microphone cable, and allow users to push-to-talk or leave the talk latched and talk freely. Either way, multiple users can talk at once, which is a huge plus over two-way radio systems (there are options that can be set to, for example, allow the stage manager to override the talk buttons on all remote stations if needed).

They're definitely more expensive, but well worth it.

ClearCom is the most common in the theatre world, although of the three I've noted, it's not necessarily the best. It's unbalanced, so very susceptible to hum from all sorts of things.

Telex AudioCom is great because it uses a balanced audio signal, so you don't get much interference/hum. The tradeoff is that it uses a theoretically super-audible tone for the call light signal instead of ClearCom's method of shorting out two of the pins, and you can hear it whine softly in the headset when it's pressed. It's also very rare; I've only once seen it at a venue (an arena I played last week, actually).

Telex RTS is very common in TV production, and in some theatres and arenas. It's huge benefit is that it fits two channels down one three-pin XLR cable, where the other methods use one cable per channel. The downside of this is that it by nature needs to use an unbalanced signal, so is not only susceptible to the same hum that ClearCom is, but can get lots of crosstalk from having two channels in the same cable (depending on other factors involved in cabling far too complex to get into here, of course).

If you want to stick with two-way radios, get good headsets that you/your crew like (everybody has their own preferenecs) to go with appropriate Motorola Radius two-way radios or similar. Don't use FRS family radios, as many do, because it is illegal to use them for commercial use.

That help a bit?


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## TechnicalRunner (Feb 7, 2005)

yes!! thanks!!  i'm going in early today to try and see what exactly is wrong with them (beltpack or headset) and see if i can make some work with working parts. hopefully some more work...opening night is friday! 
you mentioned "unbalanced signal"...could you explain that please? i sort of have an idea of what it is, but not completely. thanks! 

- Lisa


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## Andy_Leviss (Feb 7, 2005)

Try this tutorial, which will explain it more clearly than I can 

http://www.mediacollege.com/audio/balanced/


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## TechnicalRunner (Feb 7, 2005)

thanks! that makes sense


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## TechnicalRunner (Feb 8, 2005)

well last night we got 2 more headsets working, so as long as they stay that way until late saturday night we'll be ok for this show.  i talked to the director and she said we'll probably be getting new ones soon, since we'll definately need them for the musical now that most of them don't work. thanks for your help everyone!


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## TechnicalRunner (Feb 10, 2005)

yesterday i had a weird experience with our headsets...
during rehearsal, 3 of us had headsets (the 2 co-directors and myself), and one of the directors left for a little while, and turned off her headset (or so we thought). a little while later we started getting all this static on the headsets, and i noticed it was only when the actors were talking really loud/yelling/singing etc. then i thought maybe the person who left switched over to vox instead of turning it off (it's an easy mistake to make in the dark with our headsets...), which would explain why we were only hearing static when the actors were being loud (because the headset was on vox and it was picking up the sound from the house). that turned out to be the case. that wasn't the strange thing though. the other director went backstage at one point, and we heard the static again, except this time it came from her headset, which we knew was on manual...anyone know how this happened?


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## cutlunch (Feb 10, 2005)

When you say the other director, who went backstage, was on manual, do you mean that when they talked they had switch to talk. Was this static there all the time or only when she was speaking? If you post the make and model of your comms gear, someone maybe able to tell you if it is normal for this to happen. 

Walkie talkies can be affected by interference, the cheaper ones more so. Things like the dimmers can give off interference. You can sometimes spot this by seeing if the interference changes as the light levels are changed. Just the postion of one walkie talkie to another can affect the quality of reception. Buildings can also have an effect . That is why you normaly see manufacturers state usable range described as a line of sight distance.

Look for a knob marked squelch. This controls how much noise you hear when there is no one talking. If squelch is set to low and you have a weaker signal you may hear more noise. The less squelch the more static you will hear and vice versa. On some walkie talkies it is an automatic setting you can't change.


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## TechnicalRunner (Feb 10, 2005)

when the other director went backstage we heard static, and somehow she knew it was from her headset (not actually sure how, i was going to ask but got caught up in doing something else). but she wasn't trying to talk when this happened. i'm not sure of the exact model, but our headsets are from radio shack...so kinda cheap. 
i don't think it was the lights since there weren't any light changes then (basically none in the whole show...just turn them on in the beginning and off at the end - we're doing improvs). would that interfere even if there aren't any changes? 
i think our squelch might be automatic too, we really only have a talk button and one that switches from off - man - vox. 
is it possible that a cell phone could have done it? i know they have interfered with them before, and we did have a few people in the house watching last night. 
thanks for your help!


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## cutlunch (Feb 10, 2005)

TechnicalRunner said:


> is it possible that a cell phone could have done it? i know they have interfered with them before, and we did have a few people in the house watching last night.
> thanks for your help!



Hi Lisa. The lights, if on dimmers, can interfere even if they are not changing. I just meant that it is easier to detect when they do. Cell phones can interfere with audio systems. Cheap walkie talkies might be more susceptible. I just did an experiment with my cell phone. When it transmitts to the cell tower to say 'hello here I am' it puts a short burst of interference on my stereo. I knew that happened but I tried something new. I checked my messages and the whole time I was connected interference came across my stereo.

Cell phone interference is fairly recognisable once you have heard it a couple of times. So if people were using their cell phones in the theatre then you might have picked it up. Not all cell phones will produce the interference. As an experiment put on one of the headsets and get out your cell phone and talk. Try a couple of people with different models from you. If it is cell phone interference, when you get closer to the phone the interference will get worse. This is why cell phones should be switched off completely, not just on silent mode, during performances. Even if you are not using your cell it will transmit every few minutes to let the nearest cell tower it is in the area. 

Good luck with the detective work.


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## TechnicalRunner (Feb 10, 2005)

hmm that's interesting...thanks! well that will be my pre-show mission tomorrow  just out of curiousity, how do the dimmers interfere with the headsets?


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## cutlunch (Feb 12, 2005)

TechnicalRunner said:


> hmm that's interesting...thanks! well that will be my pre-show mission tomorrow  just out of curiousity, how do the dimmers interfere with the headsets?



Some of the answer is what you would study at college level electronics. I think I can give a basic explanation with the help of the link below. First I have to make sure you know how the basic dimmer works from the electronics point of view. 

The link below refers to how light dimmers, you would find in your home, work. But the principle is the same for Theatre dimmers , they just use higher rated components and a bit more control circuitry.

http://home.howstuffworks.com/dimmer-switch2.htm

If you look at the diagram. It shows what an AC mains supply signal looks like. Been AC there is a positive and negative cycle. The point at which there is no voltage is called, naturaly enough, the zero crossing point. As shown in the diagram at this point there is no power flowing to the lights.

So how the dimmer works, is by detecting the zero crossing point on each half cycle. The time delay from the zero crossing point until the TRIAC is turned on to let power flow varies the amount of power, hence the light level, that goes to the light. 

If you turn the light on just after the zero crossing point you will get most of the power available in the half cycle going to the light * = Actors saying " It's to bright and it is shining in my eyes" * :roll:. Turn it on half way through the cycle and you will get a lot less power going to the light, so it will be much dimmer * = Parent saying "I couldn't see my little Suzzie" * :roll:

Ok now you know how the dimmer works we can talk about how it causes interference.

The main cause of interference is that the rate of dv/dt is to high. Don't worry I wouldn't expect you to understand that. It just means that the voltage does not rise slowly but is suddenly switched on at a level above zero volts. Sometimes at home when you turn a light on you will hear an arcing sound in the switch as the current jumps the contacts in the switch before it is fully closed. If there is a radio nearby you may hear interfence in it. 

This similar in the dimmer packs although there won't be a spark but that sudden inrush of energy causes interference to be radiated out. If you do music you will know about harmonics. The interference comes from the TRIAC turning on 120 times a second (two half cycles of AC) but there will be interference at other frequencies which are harmonics of the 120 eg 240, 360 etc. So this interference can reach high enough frequencies to be picked up by radios, audio gear etc. Some of this interference will also travel back down the power lines from the dimmer packs along the mains supply into a piece of audio equipment such as a mixer. Here the amplifying circuits will see it as just another signal to amplify. Then amplify it along with the wanted audio signal. 

This is why you hear people say never put the sound equipment on the same phase as the dimmers. Not always possible to do. In some places they actualy use a separate transformer to provide the power for the sound system and then run this power to multiple parts of the building eg back stage , sound booth etc. This way the sound gear is all on the same phase. This also helps to minimise mains hum inteference caused by different earth potentials, but that is a story for another day.

You will know you have dimmer based inteference when it varies as the level of the lights vary. At about the 50% level the interfernce is the worst. At higher levels the lights are turned on early and the voltage that is suddenly switched on is lower so less interfernce.

Even if the dimmers aren't causing interference in your audio systems you can notice the effects in two places. 

1) The dimmer packs. In the dimmer packs, to help minimise this inteference they put a coil of wire in series with the lamp to slow down the rush of current. As you know when a current flows through a wire it causes a magnetic field and this magnetic field causes this the coil to move slightly. Since the current is being turned on and off 120 times a second this causes a buzz to be heard from the coil. If you are standing next to the dimmer when the levels are being changed you will haer the noise from the packs change. 

This applies to most of the older type dimmer packs a lot of the schools have. There are some other ways to dim the lights that don't cause as much interference. But these are newer packs, say installed in the last two years. They still cost more then the older style but will probably eventually replace the older style.

2) The lights themselves will buzz. This applies to the incandescent type of light that has a filament. The filament is a bit like a coil and the magnetic field that is created then collapses each time the current is switched on, will shake it. It is in fact this shaking that can cause a bulb to blow before the filament burns out. You can hear this shaking as a buzzing. It will be more noticable at lower light levels because the voltage is higher when the light is turned causing a bigger magnetic field.

While I am on the topic of bulbs blowing this is why sometimes you will hear the term pre-heat, in connection with the dimmer packs. When a light bulb is cold it's resistance is lower so when a voltage is applied more current flows and this bigger surge may be enough to shake the filament to bits. When the bulb is warmer the resistance is higher so less current flows causing a smaller magnetic field -> less shaking.

When you blow a light bulb at home it quite often blows as soon as you turn it on because of this cold current inrush. Pre-heat on dimmers does exactly what is says. A small voltage is feed to the bulb all the time to keep the filament warm. Pre-heat shouldn't be set so high that you can't get a blackout. You may notice a small red glow if you look right into the light.

A bit of a long story but hopefuly that answers your question.


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## Peter (Feb 12, 2005)

Thank you for that great explination!!


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## avkid (Feb 12, 2005)

got any wireless microphones?they could cause it too!


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## TechnicalRunner (Feb 15, 2005)

thank you!! that made a lot of sense (well most of it  )! i have a question though...what does TRIAC stand for or mean? 
avkid - yes we were using wireless body mics at the time...i wasn't sure if it was them though since the headsets were fine during rehearsals when we were using the wireless mics, but the night we had all the static we had a small audience, so that's why i was wondering if it was something else. 
thanks guys!!


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## cutlunch (Feb 15, 2005)

TechnicalRunner said:


> thank you!! that made a lot of sense (well most of it  )! i have a question though...what does TRIAC stand for or mean?



Lisa glad I could help. 

EDIT: TRIAC - Triode Alternating Current Switch. The name says is all. It is an electronic switch that switches on/off the AC current to your light. Another type of switch you will hear about in connection with dimmers is SCR - Silicon Controlled Rectifier. This is like a TRIAC but can handle only current flow in one direction ie to switch an AC current you need two, one for the + cycle , 1 for - cycle. The TRIAC is basicaly two SCR in one package.

The TRIAC is explained on this page from the link on Light Dimmers I posted. If you go to this link then move through the pages this should answer your questions better then I can.

http://home.howstuffworks.com/dimmer-switch3.htm


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## JahJahwarrior (Feb 15, 2005)

a little bit off topic, why are FRS radios illegal for commercial use? At our last show, well, the church we rent space from has four Radioshack bodypark wireless radios. All of them are CRAP. Very nice in their prime, I'm sure, they look very nice and expensive! Of the four, one talks and receives, the others either talk or recieve. We used twof of those, two of my radios (FRS...) and two of another tech's really nice radios. None of them would talk on the same frequency, so the techs had several different radios.....the SM and ASM, on opposite sides of the stage, used one pair to talk to each other, and another pair was used to go from the SM to the tech booth. I forget what the third pair was used for. It's funny to see people walking aorund two two cellphones, butfunnier to see someone dressed in all black with two radios and headsets!  next show, I will get all the radios organized so it's not like that. But, it will likely be using FRS radios, which apparently are illegal. Why?


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