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Wireless Sennheiser dropouts - antenna booster or remote mount antennas

Discussion in 'Sound, Music, and Intercom' started by sdauditorium, Mar 5, 2011.

  1. sdauditorium

    sdauditorium Member

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    We've been having problems with RF signal dropouts (rarely but sporadically) on a few of our newer Sennehiser EW G3 units. After troubleshooting, the problem has been narrowed down to lack of RF signal at the receivers (located in rack in sound booth in back of house, approximately 100 feet from stage).

    I'm planning to fix this and have it narrowed down to 2 options: one would be to purchase 2 sets of the Omnidirectional Antenna UHF antennas (have 3 splitters feeding off of 2 sets of 1/4 waves antennas front rackmounted currently) and remote mount those in the house in front of the sound booth.

    The other option would be to purchase 2 sets of the antenna boosters and just amplify the signal that way.

    What's the thought on which option would give the better results? The cost is almost equal, while there would be a bit of labor with mounting the antennas. My primary concern is getting the best results possible.
  2. lparks1

    lparks1 New Member

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    Try moving the antenna closer to the stage. 100' seems like a long way to rely on the receivers to get a good strong signal from the transmitters. I know they advertise (300-500' line of site) but I would no rely on that. The farther away from the transmitters, the more chance to interfering devices can cut into your signal strength.

    Several things you could try:
    1) move your entire unit (receivers/transmitters) closer to the stage and run a snake to the mixer.

    2) get Directional antenna if you don't already have them

    3) Simply move the antenna closer to the stage - but keep in mind that the further the antenna are from the receivers, your going to loose a great deal of he signal. I don't know the technical term for this (I'm sure someone else can elaborate more) and antenna boosters can introduce unwanted artifacts into the system.
  3. avkid

    avkid Not a New User

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    Are they enclosed in a metal rack?
  4. sdauditorium

    sdauditorium Member

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    They are front mounted on a metal rack, but there is no door.
  5. avkid

    avkid Not a New User

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    Try taking a few out of the rack and setting them somewhere in the booth with a clear line of sight to the stage.
    If you have no problems that should tell you distance is not your problem.
  6. mbenonis

    mbenonis <strong>Asst. Webmaster</strong><br>Wireless Guy Administrator

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    You should not be having issues at 100' from the stage. Have you checked to make sure you are not operating on top of a local TV station? How many systems are you using, and how did you plan out the frequencies?

    I highly recommend AGAINST an antenna booster. Antenna boosters (also, more properly called wideband RF amplifiers) tend to cause more problems than they fix because they amplify undesired signals and are prone to being overdriven, causing intermodulation. If you are going to buy something, spend the money on directional antennas and use passive splitters to distribute the signal to the receivers.

    See the FAQ if you haven't already.
  7. waynehoskins

    waynehoskins Active Member

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    Is there metal between the receiver antennas and the transmitter antennas, such as from having the rack turned the wrong way?

    Also, are the antennas oriented in the same (general) directions between transmitter and receiver (horizontal, vertical) with both antennas broadside to each other?

    Look at your RF meters on the receivers. With the transmitters turned off, are they showing RF signal? If so, then you're receiving interference from a co-channel station.

    How many radios are you running? How did you arrive at their frequency assignments? Intermodulation products may be part of the problem too.
  8. sdauditorium

    sdauditorium Member

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    We are running 17 units and don't have any outside interference coming in. We've had a local audio/video consultant coordinate the frequencies to avoid intermodulation. The 1/4 wave antennas we currently have are approximately 1 1/2 - 2 ft. apart and are angled in a "v" configuration. The rack is turned as much as possible to give as clear a line of sight from the antennas to stage while not putting strain on cables running from the rack to the mixer.
  9. mbenonis

    mbenonis <strong>Asst. Webmaster</strong><br>Wireless Guy Administrator

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    Can you post the list of frequencies? We can take a look at it and see what pops out...
  10. Chris15

    Chris15 CBMod CB Mods Premium Member

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    You say this is in a control room. What's the wall built of?
    Concrete say is known to have detrimental effects on RF performance...
  11. avkid

    avkid Not a New User

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    It's generally not the concrete itself that's the problem, but the metal (rebar, mesh etc.) embedded in it.
  12. mbenonis

    mbenonis <strong>Asst. Webmaster</strong><br>Wireless Guy Administrator

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    You know, I've never looked at the dielectric properties of concrete (with or without metal). Might be an interesting thing to write about...
  13. Chris15

    Chris15 CBMod CB Mods Premium Member

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    There ain't a whole lot of concrete out there that doesn't have reinforcing, especially in structural applications.

    I've seen serious attenutation at 433 MHz caused by concrete walls. The case that springs to mind was a disabled toilet that was also rated as a fire refuge. One side of the wall I had absolutely no signal strength problems. From inside I had absolutely no reception. This was a duress push button for what it's worth. Walls would have been 300mm thick or more.

    I can also tell you that the Opera House has quite a reputation as an RF dead zone for radio such as Police and Ambulance etc. and it's all concrete. Possibly there is a Faraday cage effect caused by all the rebar, that too would be an interesting thing to look into.
  14. sdauditorium

    sdauditorium Member

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    Yes, the wall is composed of concrete blocks..pretty standard. There are large windows comprised of safety glass that slide open directly in front of the rack/mixer.
  15. sdauditorium

    sdauditorium Member

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    I don't have a list of frequencies handy..however, I'll be there tomorrow and will pick it up and post it.
  16. sdauditorium

    sdauditorium Member

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    The interesting thing is, with our old EW G1 systems that these new ones replaced, we never had issues with dropouts. I know the 1/4 waves that come with the G3 series seem to be shorter and length and not comprised strictly of metal..not sure if that could have any effect.
  17. mstaylor

    mstaylor Well-Known Member

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    I have an area in my building that I can't get anything wireless, mic, cell phone or internet.
  18. TimmyP1955

    TimmyP1955 Active Member

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    Is there a need for the receivers to be at FOH? Ours (16x EW100G3 with two sets of splitters) are just off stage, and we get excellent performance by feeding each set of splitters with a pair of the whip antennas that came free with the units.
  19. chausman

    chausman Chase Premium Member

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    I see the advantages to be that you can see what levels are on the receiver and RF strength.

    If you have competent people on headset off stage, it shouldn't be a problem.
  20. lparks1

    lparks1 New Member

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    Wouldn't be an issue at all if the OP has units that feature remote control software. If he has the 300 or 500 that is certainly doable.

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