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Stage Setup

Discussion in 'Microphones' started by itsallkosher, Aug 17, 2009.

  1. itsallkosher

    itsallkosher Active Member

    Hey everyone. I'm brand new to these forums and hoping that they will help me get a better of understanding of everything audio!

    So I'm going to be running audio for our school musical production. I'm trying to find out as much about the system as I can (even though I'm only going to be turning up and down mics as actors leave/enter stage). My first question is:
    What are the BEST mics for stage out there? We have a bunch of different wig mics, around the head mics, etc, and some are old Sennheiser, some are just random brands. IF we could spend a few grand on new mics, which would be the best to buy? And I've noticed that most wireless mics for stage come with receivers, BUT we don't use those receivers in the theatre. We have a dedicated receiver for each mic (16 mics/and receivers) that we can change the frequency on. They aren't like the small receivers that come with mics, and don't have antennas. Instead, we have 2 helical antennas that I suppose pick up all the mic packs. What are those antennas connected to? Sorry for the plethora of questions, but I'm EAGER to learn about all of this stuff! Any answers are greatly appreciated and it's great to be here! Thanks!
  2. dvdhawk

    dvdhawk Well-Known Member

    Welcome to RO.

    Let me see if I can shed some light on this.

    Your wireless systems aren't any different than the usual set-up. The only difference is, you're using 2 broadband antennas, and using a antenna splitter to send those two signals to all of your receivers. So you've got receivers like everyone else, they're just properly installed.

    The "BEST" is highly subjective. I'm kinda biased, so I'll give you a number of brands that are all good - if you avoid the entry-level stuff. AKG, Countryman, Sennheiser & Shure would probably be my top 4 recommendations (In alphabetical order) for lavalier, headset, or over-the-ear, mic capsules. Many of the better capsules can be ordered with a connector compatible with the major brand transmitter packs. Or they can often be ordered without a connector - meaning someone will have to solder the appropriate connector to them. That's no easy task, because the connectors are so small - but it's a money-saving option if your transmitters and receivers are all still worth saving. (**See note below)

    Check to see how many systems can operate simultaneously with any new systems you're considering. Don't be mislead by the number of available frequencies. Some offer over a thousand frequencies you can tune to, but only recommend operating 20 systems at the same time. You have to maintain proper spacing between the channels.

    Another thing that distinguishes the "Better" and "Best" systems will be the output power of the transmitter. This equates to better range and better clarity under all circumstances. Some are as low as 12mw - (not so good), a high-end one will be 50 milliwatts.

    A bigger system should use some sort of broadband antenna system that splits your 2 "helical antennas" to feed the incoming radio signal to all of your receivers. Depending on the size of your auditorium you may have the best results mounting the antennas near the procenium (not too close to any lighting). Then you run extremely high-grade coaxial cable (like RG-213) back to the receiver rack. Or you can have the receiver rack in the wings and cable into the snake backstage. I like having the receivers at the mix-position, so I can see the RF signal levels and confirm the actors haven't switched anything off - or lost battery power.

    There's a certain amount of voodoo involved in running a bunch of wireless systems, so pay attention to the frequency spacing and keep lots of new high-quality alkaline batteries on-hand. Change batteries in every pack before every performance. Rechargeables cost a lot up-front, but pay for themselves quickly in systems that get used heavily.

    ** You should also be aware the switchover to Digital TV is intended to free up a range of frequencies that have traditionally been assigned to wireless microphones. Make sure you avoid buying systems that operate in the frequencies between (698MHz - 806MHz). They may pose a problem in the near future as more data is transmitted in that range for a wide variety of wireless devices.

    Good luck! I hope that helps.
  3. itsallkosher

    itsallkosher Active Member

    Wow thanks for the detailed reply. That clears a lot up! And I have just one more question regarding frequency ranges. Some of our Mic packs can be changed to a frequency in the 600 mHz range (from 600 mhZ to a higher number I don't remember lol. Maybe 650? 670 mHz?). It can only be set to frequencies in the 6xx range. Those packs have coinciding receivers that also can only be set in that same range. Then we have some mic packs/receivers that are in the 700 mHz range. From what I've read, those are actually banned by the FCC; apparently cell-phone providers use the 700mHz range? So what is the difference between the 600 and 700 mHz ranges? Why do some mic packs use 600 and some 700? And now that TV is no longer cast in analog, what has been freed up? What frequency range do newer mic packs use? Thanks again!
  4. dvdhawk

    dvdhawk Well-Known Member

    Your systems operate in the UHF range, and until the DTV switchover, they could coexist with the limited number and limited range of the television stations broadcasting in analog UHF. It took some planning, but you could find a clear channel for wireless mics in most major cities. In rural areas beyond the UHF broadcast fringe, you would have little conflict if any - with the exception of other nearby churches and schools.

    To run multiple systems at the same time, each system has to be running on a different frequency. If the channels are too close they interfere with each other. The manufacturer will usually recommend specific spacing for best results.

    You will want to tune your systems below 698MHz to stay clear of potential problems and phase out the 700MHz units. The 698MHz - 806MHz frequencies vacated by digitizing those UHF TV stations have been auctioned off by the FCC. They allocated some for an emergency broadcast network. And the rest will be used for a variety of wireless devices - I would imagine certain i-Palm-berry type handheld devices and the like, will be developing hardware that broadcast and receive in those bands. Some of that technology is ready to roll out, and I'm sure there's much more in development that I can't even imagine. I would think some of the broadcasts in that range will be from satellites and some from towers on the ground.

    Wireless mic manufacturers have been using UHF frequencies from around 600 - 900MHz for years. There's no significant difference in how they work, they're just on different channels. Think of these in the same way you think of FM frequencies. There's a station playing country 'music' at 95.1 and a rap station on 95.5, classical on 91.7 and classic rock on 102.5. - Different source for each, different transmitter frequency for each, you just tune your radio to lock in on the frequency you want to hear. Wireless mics are just short-range transmitters that work one-to-one. (one transmitter per one receiver).

    Does that make any sense?
  5. Codemonkey

    Codemonkey Well-Known Member

    But - I'll be wrong here - my thinking is that you can use multiple mics with a single receiver (on the same band) or multiple receivers and a single mic.

    However neither option is useful, desirable, effective or wise.
  6. itsallkosher

    itsallkosher Active Member

    So we REALLY shouldn't be using the 700MHz packs/receivers anymore? It's in Tampa, FL, so it's not a rural area. The show we did in March/April was fine with the 700MHz packs. But now, at any moment, someone who "purchased" the 700MHz frequency could start broadcasting something and render the hundreds of dollars worth of equipment useless? Or somebody browsing the internet on their Blackberry in the back row could interfere with the signal? Now, we have maybe 6 different packs within the 700MHz frequency (i.e. 700.100, 701.200, etc) btw.
  7. Codemonkey

    Codemonkey Well-Known Member

    I was in spain recently. I found so much clutter on the airwaves it's a wonder I picked up anything. Talkshows every .4MHz and the regular stations crammed in too.

    AFAIK, that'll happen to you if someone starts using it - you get their signals interfering with yours. Maybe you'll interfere with them. Or you might get lucky and the offending transmitter will experience a power cut.

    I would prioritise the changing of them - bearing in mind some might be switchable from the current setting.
  8. itsallkosher

    itsallkosher Active Member

    Thanks so much for the help guys. Much appreciated!
  9. dvdhawk

    dvdhawk Well-Known Member

    That pretty much sums up the situation. The DTV transition was delayed twice and finally went forward in June. It may not happen immediately, but it just seems like a matter of time until someone broadcasts in that 700MHz range in a city the size of Tampa. Interference may be erratic at first, but it seems almost inevitable at some point down the road. Heaven help us if the next generation of yuppie a-hole can't have a pizza delivered to his moving vehicle and update his facebook from his car while streaming a video of some guy getting kicked in the crotch.

    But I digress...

    Several of the wireless mic companies have offered modest rebates to customers who trade-in their 700MHz systems. It would only offset a fraction of the replacement cost, but it's better than nothing.

    I recently needed a system in which one mic was received by multiple receivers tuned to the same mic frequency. It worked perfectly. [ Codemonkey, remember asking about totally wireless speakers some months ago? - very slick ]

    On the other hand, running multiple mics into one receiver would be absolute chaos. The dual diversity (two antenna) receivers are always searching for the strongest available signal and try to squelch out all others. And even if by some miracle it worked for a little while, you'd have no way to mix the actors' mics, and as you suggest ineffective / unwise.
  10. Codemonkey

    Codemonkey Well-Known Member

    "[ Codemonkey, remember asking about totally wireless speakers some months ago? - very slick ]"

    I do... I since gave up on the idea. We abandoned the plan of putting the wedge and singers out front and noone budged an inch off stage.

    I had a feeling it might work; depending on whether the unit sums all the one-way signals from mics on a given frequency or if it selects the strongest signal and uses a two-way connection.

    "a pizza delivered to his moving vehicle"
    Great idea for a game! High speed car chases with pizza, it's a must for any gamer.
  11. itsallkosher

    itsallkosher Active Member

    What exactly would be the point of having multiple receivers tuned to the same mic frequency? And can you purchase a mic receiver by itself? What would be the difference between a cheaper or more expensive model if they are going to be connected to the helical antennas anyway?
  12. dvdhawk

    dvdhawk Well-Known Member

    This was a unique installation where the client wanted the ability to have 6 speakers suspended throughout a small park - without any wires pole to pole. They wanted it to be simple and wanted a single wireless mic to be the only source. The K&H speakers we used can operate completely wirelessly (including rechargeable if needed). They are weather-resistant, so they chose to provide power at the top of each pole so they could leave them up for a week at a time for their annual event. Then use a bucket-truck to get them down when they're done. Each speaker has an expansion slot for a wireless receiver and a second slot for CD player or whatever. We put a receiver in each speaker all tuned to the same freq. All you have to do is switch ON the mic and you're done. It doesn't get any simpler than that. They're crystal clear, as you would expect from K&H speakers, and project very well through the small park.

    Most of the major manufacturers will sell separate components.

    Quality of the audio components aside. Output power of the transmitter is a big factor in better systems. In my opinion, the transmitter is more crucial than the receiver, but they have to work hand-in-hand. There's all kind of technology involved in "tone-code-squelch" / signal companding / phase-locked-loop tuning that are vital in locking in on a clean radio signal that I'm not sure you're ready for yet.

    I hope that helps.
  13. itsallkosher

    itsallkosher Active Member

    Thanks again for all the knowledge! This is turning out to be a great forum! :D

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