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Video via mic cable

Discussion in 'Multimedia, Projection, and Show Control' started by Stoldal, Jun 6, 2008.

  1. Stoldal

    Stoldal Active Member

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    I was asked to help with a dance performance and they want a back stage video monitor.

    The video source is about 400-500' way from the monitor. So my audio guy says that we can use a RCA to XLR and use 4-5 100' run of XLR mic cable.

    First can that be done?

    Second question, what is going to be better RG6 or mic cable, yes that may sound like a silly question.

    I just don't want to tell him no thats not going to work, he want to know why it does not work.


    ___________________________________________________
    Part 2

    What i plan to do is have one 400' or 500' run of RG6 cable, the signal is going to be coming from a RF modulator. Do i need amplifier.


    Thanks!!

    Matt Stoldal
     
  2. PadawanGeek

    PadawanGeek Active Member

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    I was wondering about that so I did a simple test adapting the video from my Playstation for XLR and then back again and it worked. However, it is not a good idea. The video signal coming thought looked a bit weird and sometimes when gray. Bottom line: Only do this if you can afford for the monitor to sometimes stop working and the video signal not to be its best quality. Only use this in a big big pinch.
     
  3. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    As Pad said, it's possible, but not recommended. Try the 500' mic run, (preferably without actually running the cable), and if you don't like the results, use the RG-6. See this post.
     
  4. ruinexplorer

    ruinexplorer Minion CB Mods Premium Member Fight Leukemia

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    I recommend ignoring the XLR, too much chance for signal problems. RG6 isn't that expensive and you will likely use it again. Yes, if you have one available, I would use an amplifier on that length of run for better quality.
     
  5. mbenonis

    mbenonis Wireless Guy Administrator Premium Member

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    I recommend the RG6 as well, but DON'T use an RF modulator! You'll get MUCH better results if you just send the composite signal straight down the cable (using a composite video amplifier if necessary). Composite video is 0-6 MHz and Ch 3/4 is at 60-72 MHz - you'll get less attenuation per 100' at 0-6 MHz.

    To connect it up, just get F to RCA adaptors - a few bucks at your local ShadioRack.
     
  6. propmonkey

    propmonkey Well-Known Member

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  7. Stoldal

    Stoldal Active Member

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  8. incstlouis

    incstlouis Member

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  9. mbenonis

    mbenonis Wireless Guy Administrator Premium Member

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    Those RG6 prices seem about right. The best terminations to get are the Thomas and Betts Snap n' Seal connectors for RG6 Quad Shield (purple insert). Tri State Electronics sells them, among other places. They're a bit expensive but also not likely to fail. You'll need a tool to put them on as well as a coax stripper (believe me, for the $3-5 for the stripper you'll thank me down the road!)
     
  10. Stoldal

    Stoldal Active Member

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    ok, so i just found out that the video feed is going to be recorded, the video mixer is going to be at the end of the cable run, so i am going to get an amp, now the question is what one would work, btw the camera is a DVX100.

    I have the Cable is just the standard RG6/U. Not the best but not the worst.

    will something like Kramer Electronics USA PT-102VN 1:2 Composite Video Distribution Amplifier

    or

    VetcoElectronics.com

    work, or do i need to ask to borrow one from my dad.

    (side note: my dad run the one of the local news stations, KLAS channel 8, one of the first to go Full HD.)
     
  11. FMEng

    FMEng Well-Known Member Fight Leukemia

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    You don't need an amp for that length of run. It'll accomplish nothing, so save your money.
     
  12. SHARYNF

    SHARYNF Well-Known Member

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  13. LDTom

    LDTom Member

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    For many years I was the house LD at a club here in CA. Every time that Berlin came through the club they had video content that they wanted on the video screens which were around the club. We tried the first couple of times that they came throught to go RCA-To the XLR stage split and then out of the FOH snake to a RCA adapter and this didn't always work and picked up line noise and had a potential for looking like a scrambled TV channel. The way that worked the best was running RG-6 with RCA adapters on each end of it. We also used a 250 foot run of expensive RCA cables which worked but was expensive.

    Also make sure to have everything grounded on the same ground to avoid any extra hum, but you should always carry video and audio hum eliminators. If the video in anyway is going through a mixer to the sound board there might be the need for a Ground lift, but each room is different.

    The room that I used to work in had ground loops up the yin yang.:lol:
     
  14. Andy_Leviss

    Andy_Leviss Active Member Premium Member

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    You can run video over mic cable (although it's cleaner over digital-grade cable), but you need a special transformer device known as a baluns. This converts it to a balanced signal that can happily run over mic cable, CAT-5, etc.

    "They" do make BNC to XLR adapters, but they're not really meant for that. And it's not worth the headache. I learned firsthand when the first tour I was out on used those to send our PSM's four video shots over audio mults. When it worked well, it was great, but when it acted up, nothing I could do could fix it, since it was inherent in the physics of it, and you don't want to be the one explaining to the PSM why his/her video can't be fixed because of physics :-D
     
  15. kwotipka

    kwotipka Active Member

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    From a broadcast perspective, 1200' is forever and a day for composite video right out of a camera. Yes you will get a signal out of the other end but it will in no way be the best it can be. It may not be enough for your switcher to derive sync reference from. Just doing the math in my head, I come up with around 6dB of attenuation. The biggest issue you will have is equalization which will effect the details in the image. The short of it is with poor eq, the image is not as sharp. You can get equalizing DA's from companies like Tektronics but this will require a scope or someone who knows how to do it with a multimeter to do it correctly.

    A D/A or 2 in line wouldn't hurt but you will most likely have to power it from the same place as the switcher to avoid ground loops. Also, keep it away from the lighting cable as well. You only have a 1Vp-p signal there so you want to keep it as happy as possible.

    Now, in the spirit of low budget projects, I would recommend that you roll tape in the camcorder so that it could replace what is recorded at the switcher later if that is possible.

    I have run video down the audio snake on occasion with mixed results. Usually you need a humbucker and the best distance I got was about 200'. After that, the impedance and eq are shot and the signal goes south fast. I would never recommend recording the signal using this method. Monitoring only.

    Your other option would be a fiber run. Then you would have a great signal at the console.

    Either way, power up the camera and switcher and put the 1200' inline before the day of the shoot to ensure that the whole mess will work.

    Let us know how it turns out.

    kw
     
  16. Stoldal

    Stoldal Active Member

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    The longest run is 500', it is a three camera shot and in total we will be using
    about 765' feet, one is back stage, about 15' away from the mixer, one is at the FoH (aka: the 500' run) and then the last one is about 250' away from the mixer.
     
  17. kwotipka

    kwotipka Active Member

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    Where did I get 1200'? Time to get some sleep.

    kw
     
  18. Stoldal

    Stoldal Active Member

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    So i just finished up with the show, it went good.

    The longest run turned out to be about 450'. We worked it so the video mixer would be next to the camera that is the feed for the backstage video moniter.

    The second camera was only about 75'.
     
  19. headcrab

    headcrab Active Member

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    I wanted to do a similar thing at my school. We have a camera with composite output and we wanted to send it back stage for a video monitor. We put in a CAT5E cable and put the signal over one pair. It works reasonably well. coax with an amp would probably be better, but we can't afford that.
     
  20. pacman

    pacman Active Member

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    You might check out UTP Distribution Category- Analog the MultiView products from Magenta Research. You can send any flavor of AV up to 1920x1200 and control signals over CAT5 up to 2000 feet. I'm using some of their gear and quality is really good. Unless you are at the extremes in resolution and distance, standard Cat 5/5e is adequate; they do recommend skew-free cable if you are pushing distance and resolution. You can run lower resolutions well beyond 2000 feet.
     

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