pre wireing for front projector (1 Viewer)

[tom dettling]

I have decided so far to pre-wire for a front projector using (1)DVI-D, (1)Composite(5BNC's), (1)S-video and extra rg-6(f)connector. Should I add or take away from this list because their is no upgrading later. (unless i want to spend a ton of money to rip up the living room)

Second question is i want to terminate the wire at the wall and have extra in the ceiling to be used for a pole mounted ceiling projector. Their are a few companies that will fabricate the face plate and put the amount of feet of wire you need. I have talked to only one home theater store and he was against this idea. His reasoning of keeping to the least contact points sounded good to me but i want a second opinion. To terminate or not to terminate at the wall that is the question. As i am writing this why can't i terminate at the ceiling also.

Thanks for reading this.

 

[Bob McElfresh]

I dont think you can get a DVI cable that works past about 6 feet. There are multiple digital signals bundled together and they dont work well over long runs.

I also recommend trying to create a un-broken cable run from source to projector. Leave some of the video cable running in lazy "S" curves in the wall.

If you really, really want to do face plates - get them with BNC connectors, not RCA plugs.

High-frequency video signals are sensitive to impedence-mismatch. RCA plugs are horrible for maintaining the 75 ohm impedence of the coax. The BNC connector is superior to the RCA which is why nearly all professional video gear uses BNC rather than RCA plugs.

There are several custom cable sites that sell "SVideo Breakout Cables". These run about $100 but they are a SVideo connector with 2 mini-coax cables ending in BNC connectors. You use these near the equipment and run matching BNC terminated coax for the bulk of the run.

With these "breakout" adaptors, you can use BNC connectors for all 3 of your runs.

 

[Gabriel_Lam]

What lengths are you running? DVI-D in long lengths are difficult, though depending on your budget and your target resolution/refresh, doable.

 

[tom dettling]

The Cable length is 7 ft up the wall and 13-15 ft to the seating area plus a little more. I would say about about 25 feet. That does not included going to the source. I like the idea of terminating at the wall.(A more cleaner look) If i do this is that a bad thing?

 

[Gabriel_Lam]

Terminating at the wall is an EXTREMELY bad thing for DVI. Very very bad, especially considering how long you're running it. I'd suggest making a face plate with a hole in it. You can cap the hole if it's not in use, or pull the wire through it when you are using it.

You can wrap all your wire together in flexowrap to give it a nice finished look. It has that high quality braided fiber look of high end cables.



BetterCables makes the 9 meter DVI cable that I'm using for my 1400x1050 native projector. Cobaltcables makes good ones as well. If you don't plan to run as high resolution, you can probably use something less expensive.

 

[Bob McElfresh]

Wow! I have heard of people having problems with more than 2 Meter DVI cables. Guess I'm wrong about the length-limit.

 

[Gabriel_Lam]

Nah, you're not entirely wrong. It depends on resolution and cable quality.

For instance, my Panasonic 42" plasma's DVI blade came with a 3 meter cable, the thinnest DVI cable I've ever seen. When I tried to use it with my 24.1" LCD monitor (1920x1200p native resolution with 60hz refresh), it looked horrible. There were pixels of color everywhere.

As the cable gets longer, it becomes harder and harder to support high bandwidth. So while 1080p may be out, 720p may still work with most cables at that length.

 

[Rutgar]

Since most apps with Front Projectors require longer runs than 3 or 4 meters, what about using one of the DVI Distribution Amplifiers available? They claim that you can use runs up to 100 feet with the amps. Any quality issues that people know of?

- Rutgar

 

[Gabriel_Lam]

I haven't heard of any problems with the amplifiers.