video cable from computer to projectors?

[llewop]

I am installing a new multi media / sound booth at my church.
we have two projectors at the front of the church and the boothis at the back about 150' away.
I now have multi conductor cable through a splitter run to each projector.
Can I use coax instead?

[museav]

What "multi conductor cable" is currently run? Do you mean a VGA type cable? What will the source be and what signal types does it output? What physical input connectivity do the projectors support? What is the splitter and are you going to replace it if you run a different signal or cable type? Are you asking about running a single coax or multiple coax? Are there any limitations in regards to the cable paths, such as it all having to fit in a certain size conduit?

[llewop]

I am pretty sure it is a vga cable ( it looks similar to an RS232 conn ) and a single cable runs from my computer via a 75' cable to a splitter and then leaves on two 100' cables. One to each of two projectors. The same type of cable. The signal consists of power point presentations and DVD presentations.. just what ever we can display on the computer in the sound booth.
I am attempting to find out if COAX is a good way to, with a simple splitter, get my video to the projectors. Will it support good resolution and quality? I think the projectors have provisions for coax. I could be wrong. I will look.
At any rate the signal could be converted if necessary, right?
I will be installing this coax behind ceiling tiles.

[llewop]

The projectors does not have coax connectors on it.
They are EPSON S6's
The cables I am using now are mulitconductor D-sub connectors on each end.

[JohnHartman]

Are you looking to replace the VGA which is currently run? Or are you looking to be able to send a composite video signal separately?

It sounds like the cable you currently have run are HD15 plugs a D-connector with 3 rows of 5 pins each. Or commonly known as VGA cable.

[museav]

The projector has computer (HD15), S-Video (4 pin mini-DIN) and composite (RCA) video inputs. You could scan convert the computer signal or the computer may even provide a composite or S-Video output and you could use BNC to RCA adapters on the end for the RCA video input on the projector but this approach would be virtually guaranteed to result in lower resolution and image quality than staying with the computer video signal.

That being said, 75' from the computer to an unknown 'splitter' and then another 100' to the projectors are long runs for generic VGA cable. Inside the VGA cable are multiple conductors and for a projector five of them (red, green, blue, horizontal sync and vertical sync) are required. Signal losses from the cable runs could be reduced through the use of bundled coax cable (five coax cables in one overall jacket) and breakout adapters such as this, Extron Adapters - SY VGAM-RGBHVF - Pigtail, at the ends.

So yes, coax could be used, but getting any improvement would be in the form of using five wire bundled coax and VGA adapters in place of the VGA cables rather than converting to composite video on a single coax, which would likely reduce the image quality.

You mentioned the cables running above the ceiling so another consideration is that if the area above the ceiling is considered a plenum space then any cables run exposed in that space need to be plenum rated.

[SeanInNZ]

Hi, if I can offer my 2c worth. I have found that no matter what kind on money you throw at getting a good cable to improve the quality of your video, particulary VGA from a computer, you will always be disappointed. I have done a few installs of even 10-15m and found there is sufficient degradation in the quality to be noticable.

The best way to get VGA (or DVI or even HDMI) is to use converters to CAT-5 cabling. This is done by converting VGA to balanced signals and jamming them down cheap CAT-5 (which is generally used for standand Ehternet networking, and cost less that a dollar per meter). Then the signal is converted back at the projector end from balanced back to VGA.

The image is still nice and crisp and clean. It does NOT exhibit the problem of fuzzing and blurring, and often what they call 'banding', which is a thick band which slowly creaps up the image, then folds around at the bottom. Nothing like it.

Here is one place you can get the units (they come in pairs, normally).

VGA Extender Kit (2-Port Local, 2-Port Remote) - AC555A - Shop now - Black Box

They have a host of other solutions, but this is about the cheapest and the very ones I used. Worked a dream, and I think that if you compare the installed price between the options, this will probably work out to be the cheapest. They also have wireless units, but this comes at a price. If you are running 2 or more projectors, then they also have the option of the 'local' unit (the unit at the computer end) having multiple CAT-5 outputs, so you can run to multiple projectors. this is a little more costly though, but still cheaper, and cleaner, that running the expensive, bulky and noisy cables.

Let me now how it goes.

Cheers, Sean

[museav]

Originally Posted by SeanInNZ

Hi, if I can offer my 2c worth. I have found that no matter what kind on money you throw at getting a good cable to improve the quality of your video, particulary VGA from a computer, you will always be disappointed. I have done a few installs of even 10-15m and found there is sufficient degradation in the quality to be noticable.

Just to clarify, were those situations using generic "VGA" cable or high quality bundled coax? I have many times run computer signals well over 30m without any problems when using five wire bundled coax. It is a physically large and more expensive cable but it also avoids potential issues such as skew that can occur if you use long runs of typical UTP cable (CAT6 is worse than CAT for this) and interfaces with no skew compensation.

One thing to consider is that it may not be that long until you see source devices and computers that either only have digital outputs such as SDI, HDMI and DisplayPort or that only support analog outputs at lower resolutions. To plan for that a UTP based solution may make more sense, however you may want to run two or three cables instead of one as some signals will require more than one physical cable to handle all the information.

[mrb]

with VGA, its all about the cable quality. I routinely run VGA 100'-200' with no problems. The trick is to use proper VGA cables. The right cable has three coax inside it, plus a bunch of twisted pairs for the signal lines. The lower quality VGA cables dont have coax inside, theyre just a bunch of individual wires.

[JohnHartman]

mrb not sure what VGA you have been using. all of the VGA cable I have used have 5 coax in them. for the 5 signals RGBHV. The grade and quality of cable varies based on the quality of the coax used in the manufacture. I have an installed facility that had hundreds of feet of RGBHV run through 4 floors of an office building in NYC which all ran flawlessly The longest run covered 4 verticle floors and transversed approximately 150' latterly granted there were line drivers installed on the lines but they all functioned flawlessly for years.
We just replaced them with fiberoptic transcievers.