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Author Topic: video distribution  (Read 3964 times)

Kristian Stevenson

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video distribution
« on: November 04, 2007, 03:41:21 PM »

Our church is building a family life center and in it is going to be a room for the youth. We have a nice Prjector/LCD system figured up for our needs, but now i am stuck on the best way  to get signal to all the displays. I am thinking about going with a 6x1 VGA distribution amp and run VGA cables to every thing. I was also thinking of S-video because the distribution amp is cheaper along with the cable, but there is a lack of quality compared to high rez VGA. We are planning on running a computer and DVD player through the system. For the DVD player I am going to purchase a Component to VGA switcher so it can send the signal with just the one VGA cable. The setup is like this: projector for the big screen up front, LCD's on the left and right walls about mid-way back, and two more smaller LCD's in the very back of the room.(heres a home-made plan for yaw visual people Cool )
index.php/fa/189/0/

So I guess my question is whether VGA cable and a VGA distribution amp is the best/cheapest way to send signal to all those displays.

thanks,
Kristian
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Tim Urner

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Re: video distribution
« Reply #1 on: November 06, 2007, 06:48:12 AM »

All VGA may be the cheapest. However, we have been doing VGA over Cat5. We found the there is a quality difference when the VGA run is long, even when the VGA signal is amplified. The cat 5 just looks better. Cat5 will not be that much more expensive. Cat 5 cable is cheaper, but you need more gear. Another plus is you can run just about anything over it you want. VGA, S-Video, Audio, etc.. you just need the right converters on the end. There are several companies that do the Cat 5 distro stuff, search google. We usually use Kramer

I would stay away from S-Video for your distro system.

My advice would be get a scaler switcher,  run all of your sources into that,  and distro by cat 5. That should be a reasonable in cost and quality.

Brad Weber

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Re: video distribution
« Reply #2 on: November 06, 2007, 04:09:41 PM »

Tim Urner wrote on Tue, 06 November 2007 06:48

All VGA may be the cheapest. However, we have been doing VGA over Cat5. We found the there is a quality difference when the VGA run is long, even when the VGA signal is amplified. The cat 5 just looks better.

Sounds like you have a bad signal or are using cheap cable.  In my experience, properly setup VGA/RGBHV distribution with good quality multiple coax cable will look better than running over UTP unless you have very long runs.  I have also seen video over CAT5 signal using cheap interfaces or that was poorly setup and that looked horrendous.  In both cases, it is a matter of implementing the right solution for the application, using good quality equipment and providing proper setup and adjustment.

Another consideration will be what conduit or cabling paths are available.  Bundled 5-wire coax may not be practical due simply to the size of the cable.  And the distances involved are a critical component to the cost.  As Tim noted, CAT5 solutions require interfaces on both ends, but the cable is typically much less expensive than good quality RGBHV cable.  So at some total distance of cabling the cost advantage may switch from RGBHV to CAT5.

One thing to consider with a scaler/switcher is to be sure to check what resolutions the displays and projector support, you may find that you have a limited number of resolutions that all of them accept.  I often find that you have to set the scaler output for something like 1024x768 even though all the displays could handle higher resolutions individually because that is the native resolution of the primary display and/or it is the highest resolution that all the various displays can accept.
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Brad Weber
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Kristian Stevenson

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Re: video distribution
« Reply #3 on: November 07, 2007, 06:03:08 AM »

i'm guessing that when you say "5 wire coax", you are refering to the 15 pin VGA cable i was talking about. The runs I am having to make shouldnt be more than 100ft anywhere. And with the price of those cat5 transmitters/receivers, I think I will just stick to a distribution amp and VGA cable.

Like you said with the resolutions, our projector only goes up to 1024x768, so thats what I will set all the inputs too.

Our projector has 16:9 capabilities but is native at 4:3, but most LCD's nowadays are widescreen, so what I was going to do was send a 4:3 signal to all displays and let the LCDS have the "grey boxes to the left and right of the picture. I'm afriad that if I went with everything 16:9, the projector screen wouldnt be big enough and we would have to up the 2nd graphics card in our pc to make sure it has widescreen capabiilities.
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Brad Weber

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Re: video distribution
« Reply #4 on: November 07, 2007, 09:16:03 AM »

It may still be 15 pin connectors at each end, but do not use 'VGA' cables.  The problem is that most 'VGA' cable is meant to run a few feet to a monitor, not 100' to a remote display.  And while used as a generic term, VGA is technically 640x480 resolution, they'll handle higher resolutions but some 'VGA' devices and cables aren't really designed for that purpose.  Also, if the runs aren't in conduit, consider whether plenum cable may be required.


Instead use bundled 5 mini-coax cables like this http://www.extron.com/product/product.aspx?id=bnc5mhrcable&a mp;subtype=48 or this http://www.canare.com/index.cfm?objectid=0CFA20EB-3048-7098- AF95E4502E42FDA0 (V5-5C).  You can also buy terminated cables using this type of cabling with HD15 ( http://www.extron.com/product/product.aspx?id=mmvgamoldconc& amp;subtype=55) or BNC ( http://www.extron.com/product/product.aspx?id=5condmhrbncmbn cmc&subtype=54) or mixed ( http://www.extron.com/product/product.aspx?id=syvgamalefibnc maleca&subtype=58) terminations.  I think that just about all of these are available in plenum versions if required.  Many projectors and displays have both 5 wire RGBHV and VGA HD15 connections, I prefer to use BNC terminations and connect to BNC inputs if possible, a lot larger pin area for better contact. I'll also use an RGBHV DA rather than a VGA DA if possible.

Good quality bundled coax is not cheap, which may affect the decision versus CAT5.  At the same time, you want to compare it to higher quality CAT5 interfaces and not the low cost, off brand passive baluns.

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Brad Weber
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Kristian Stevenson

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Re: video distribution
« Reply #5 on: November 07, 2007, 03:40:07 PM »

when I say VGA cable i am refering to the connector on the end. my projector only has the 15-pin VGA style connector. The longest run I am planning to make is no more than 100 feet and the distribution amp I am looking at says it is capable of sending the signal 280 feet, so i think i'm good there. Now my question is what is Plenum?? The contractor couldnt put in the conduit becuase it would be a big fee  towards our church to change the design so im gonna have to go with the "no conduit" option here.

If I am following you I need something like this:
http://allprosound.com/catalog/productdetails.asp?fprodid=30 10&item=Kramer%20-%20C-GM/GM-150(except in my needed lengths)

thanks,
Kristian

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Arnold B. Krueger

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Re: video distribution
« Reply #6 on: November 13, 2007, 07:19:47 PM »

[quote title=Kristian Stevenson wrote on Sun, 04 November 2007 20:41]
So I guess my question is whether VGA cable and a VGA distribution amp is the best/cheapest way to send signal to all those displays.

Did I miss the dimensions of the room, including ceiling height? The recommendation will be dependent on total cable run from DA to each display.

Also, what is the size of the picture you are going to display? 1024 x 768 or more or less?  More pixels means broader bandwidth, and that makes length much more important.

Distance makes a big difference with VGA. Up to about 100' of cable, a good DA and good quality multiconductor VGA cable will likely do the job @ 1024 x 768 x 60 Hz. By good quality DA I mean one with > 250 MHz bendwidth that has adjustable gain for each set of outputs.

Beyond 100' runs (more or less), fanning the multiconductor cable out into 5 parallel runs (AKA RGBVH) of RG6 coax (hopefully with 18 gauge solid copper cores) makes sense. There are economical adapter cables that faciliate hooking the coax w/BNC connectors up to the usual 15 pin VGA connectors - about $25 each.
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Brian Kent Tennyson

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Re: video distribution
« Reply #7 on: November 19, 2007, 10:15:31 AM »

It doesn't matter what the DA says it can do if you don't use the right cable. 100' runs require no less that RG-6 cable. you can get five pair RG-6 in a plenum rated cable (only needed if you are running in an open air return plenum) and it's very stiff (doesn't bend easy). RGB RG-6 five pair plenum rated is about 2.10 a foot retail and non Plenum is about 4.90 a foot.

You will also need a way to terminate the ends properly. I would recommend BNC connectors and a BNC to VGA pigtail as you will not be able to bend the cable into the display with just a VGA connector on the end.
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ProSoundWeb Community

Re: video distribution
« Reply #7 on: November 19, 2007, 10:15:31 AM »


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