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  • Computer to onstage projectors

    Posted by Dene Wilby on April 30, 2010 at 11:58 am

    Hi

    I work for a band and i’m in the process of setting up a computer based system to replace our DVD system.

    With the old system I had 3 DVD players fed to 3 projectors on stage via composite cable.

    I’m setting up a system using GrandVJ sent to a Matrox TripleHead2Go.

    Am I OK to run long VGA cable to the stage without degradation of quality? These are only 1,000 max capacity venues, nothing too big. I’m thinking 50 to 60m should do the job at most places and if not, i’ll run it from the side of the stage.

    Is there degradation over that length? I’ve read conflicting reports. Surely, whatever I get will be better quality than what I have been using? Right?

    What kind of degradation (if any) should I expect?

    Thanks for any advice you can throw my way.

    Cheers

    Dene

    Robert Lubiran replied 15 years, 11 months ago 5 Members · 14 Replies
  • 14 Replies
  • Walter Soyka

    April 30, 2010 at 6:55 pm

    That strikes me as quite a long run for VGA cable.

    You might look into Cat-5e VGA extenders for runs like that. Side bonus — Cat-5e cable is cheaper, thinner, lighter, and easier to work with than VGA cable.

    Walter Soyka
    Principal & Designer at Keen Live
    Motion Graphics, Widescreen Events, Presentation Design, and Consulting
    RenderBreak Blog – What I’m thinking when my workstation’s thinking
    Creative Cow Forum Host: Live & Stage Events

  • Dene Wilby

    April 30, 2010 at 7:19 pm

    hmmm, would I need one of those extenders for each of the 3 outputs of the matrox card?

    when I look into that I see that they are also good for about 50 metres. What would the benefits be, apart from having lighter, more manageable cable?

    thanks

    Dene

  • Walter Soyka

    April 30, 2010 at 7:33 pm

    There’s no such thing as an absolute cable length limit for VGA — it depends on the resolution and refresh rate, the graphics card driving it, and the quality of the cable itself. I wouldn’t attempt more than 15 or 20 meters with HD15 VGA cable.

    For an analog run of that length, most events would use a DA (or line driver) with 5-wire coaxial cable with BNC connectors instead of HD15.

    The Cat5 extenders actually work across the whole distance. Some companies have units that can go significantly farther than 50m.

    Walter Soyka
    Principal & Designer at Keen Live
    Motion Graphics, Widescreen Events, Presentation Design, and Consulting
    RenderBreak Blog – What I’m thinking when my workstation’s thinking
    Creative Cow Forum Host: Live & Stage Events

  • Dene Wilby

    April 30, 2010 at 7:43 pm

    Hi,

    I appreciate your advice but i don’t do this on a professional level so excuse my ignorance:

    >For an analog run of that length, most events would use a DA (or line driver) with 5-wire coaxial cable >with BNC connectors instead of HD15.

    So what do I need for this? I have HD15 outputs on the Matrox card and HD15 inputs on the Projectors.

    I just need to find an affordable (to us) solution that we can use for 3 shows in a row (in different venues). Why would you not use a 50m HD15 to HD15? What are the downfalls?

    Sorry, i’m just trying to understand this final piece of the puzzle.

    I’d probably be outputting at 800×600 by the way.

    Dene

  • Walter Soyka

    April 30, 2010 at 7:45 pm

    I forgot to mention this before — one of the biggest problems of trying to extend VGA too far isn’t just loss of picture quality (like you may have seen with long composite runs), but an absolute loss of picture. The projector may not be able to keep a lock on the sync signal if it’s too weak, and if it lost sync, it would drop the image entirely.

    Walter Soyka
    Principal & Designer at Keen Live
    Motion Graphics, Widescreen Events, Presentation Design, and Consulting
    RenderBreak Blog – What I’m thinking when my workstation’s thinking
    Creative Cow Forum Host: Live & Stage Events

  • Walter Soyka

    April 30, 2010 at 7:50 pm

    You’d need 6 VGA/RGBHV fan-out cables, 3 long RGBHV cables, and 3 RGBHV DA’s to place by the Matrox devices to act as signal amplifiers. You may also need 3 humbuckers by the projectors to eliminate electrical hum.

    If you only need it for 3 gigs in a row, it might be cheaper and easier to rent the Cat5 extenders from a local staging company.

    Walter Soyka
    Principal & Designer at Keen Live
    Motion Graphics, Widescreen Events, Presentation Design, and Consulting
    RenderBreak Blog – What I’m thinking when my workstation’s thinking
    Creative Cow Forum Host: Live & Stage Events

  • Dene Wilby

    April 30, 2010 at 7:53 pm

    Thanks for the advice, I will look more into this. Also, the advice about the loss of signal over long lengths is very important, thanks for making me understand that.

    We do about 10 to 15 shows a year so we need to own the correct equipment really. We’ve been using some real ‘makeshift’ gear over the past 6 years and need to take it up a level.

    Dene

  • Thomas Leong

    May 1, 2010 at 3:16 am

    I’ve used 100m HD-15 to HD-15 for b&w Stage Teleprompters, and did not notice any degradation such ghosting or loss of signal. So 50-60m should be fine in my view.

    But VGA Extenders are far lighter. Besides with the right tools in the bag, one can make up an RJ-45 quickly when required, versus HD-15. And if you are too tired after the gig, you can dump the CAT-5 cables without a second thought. Lately I’ve been using the ATEN VGA Extender VE-150 which is supposed to handle up to 150m. I’ve only taken it up to 100m though. They are about one of the cheapest on the market, bought at less then US$200 a set. Only thing is you need a power source at both ends. At the Local (source) end, the unit has a HD-15 monitor out which is convenient.

  • Dene Wilby

    May 1, 2010 at 11:14 am

    Thomas and Walter

    Thanks guys, this thread has helped me tremendously. I sincerely appreciate you directing me to VGA extenders, that is definitely the last piece of the puzzle. Do these look like good units?

    https://www.maplin.co.uk/module.aspx?moduleno=45472

    If so, i’ve setup the new system for less than £1,500 which is just great and like Thomas says, Cat5e is pretty much ‘disposable’.

    Cheers

    Dene

  • Joel Servetz

    May 1, 2010 at 12:41 pm

    The vga to cat-5 extender is a very good idea for long runs. I have done literally hundreds of events involving multiple long (100′ – 150′) vga runs to projectors and monitors using Extron VGA-DAs which are capable of runs of up to 250′. Long (100′ or more) VGA cables are thick and heavy and prone to failure from mis-handling so treat them with care and have plenty of backups.

    Joel Servetz
    RGB Media Services, LLC
    Sarasota, Fl
    videobyjoel@aol.com

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