I don't want to have Monster Cable nightmares!

September 5, 2007 11:47 AM

AVFilter: Can I extend HDMI over CAT5? No baluns or fancy equipment - just copper, baby!

Is there anything special about HDMI / DVI / VGA cables that would prevent me from just splicing a few Cat5/Cat5e/Cat6 cables and video extension cables and make up some panels? I know there are boxes that will drive HDMI over one ethernet-ish cable, but let's stay I have access to unlimited Cat5 and I want a 50-ft. HDMI cable under $20. Can I tie-wrap three Cat5 cables in between the HDMI female jacks and create an "uber-cable"? I've done it with composite and S-Video over 50 ft. with great success, so I figure..why not a digital signal, right? But before I go slicing up cables and making promises, I thought I might ask over what the benefit is over buying "real" cables. Yes, I'm more willing to splice cables for a half hour than I am to pay $250 for a cable which appears to be nothing more than a fancy connector and some copper stranded wire.

Also I'm asking because of the egregious price differences in USB cables example given on this page (a $30 difference between two seemingly identical six-foot cables).

Thanks in advance!

posted by ostranenie to media & arts (5 comments total)

don't buy monster cable. this HDMI cable is $60 and 50' long. (I've bought things from them before, but not in a while.) 1080p video requires more bandwidth than your average ethernet cable is designed to deal with - the Cat5e and Cat6 cable is good for up to 1Gbit, pretty much, and the new HDMI 1.3 is 10Gbit. if you want to roll your own, I certainly wouldn't splice a cable - just go buy some STP and some HDMI ends and wire it that way. better chance of it working. svideo and composite have much lower requirements, as they're not moving as much data.
posted by mrg at 12:01 PM on September 5, 2007

Great price on the 50' HDMI cable, thanks a lot! I just checked bestbuy.com and found a $90 8' cable without even trying. What a difference...

What makes "real" HDMI so magical though, to where it's rated for higher bandwidth? Shielding? Special conductors made out of Plutonium Nyborg? According to the ever-present Wikipedia, I can supposedly make a cable out of dual Cat-5 cables that will extend 100m (~320ft.) (I didn't notice this article before posting the original question, but I would still definitely like some objective feedback).
posted by ostranenie at 12:26 PM on September 5, 2007

I've been recommending monoprice.com for HDMI cables. I haven't tried their 50' ones but for shorter lengths their cables are *vastly* cheaper than anything from one of the big box stores. See this search for their 50' HDMI cables.

Speaking of Monster Cable, you may find this series of Gizmodo posts interesting (1 2 3 4), where they tested a range of cables from expensive Monster cables to cheaper ones from places like Monoprice.

"Real" HDMI cable is rated for high bandwith and is pretty heavily shielded, more so than CAT5 cable. Whether or not your CAT5 cable will still work though, I can't say. Honestly, if you're good with a crimping tool and have the cable already, give it a shot.
posted by reptile at 1:24 PM on September 5, 2007 [1 favorite has favorites]

Looking at the pinout for HDMI on the Wikipedia site, I think you could use Cat5, but how you wire it would be important. You wouldn't just want to hook the wires up willy-nilly. I think you'd want to put the "+" and "-" for each "Data" line (e.g. "Data1+" and "Data1-") on the two halves of each pair in the Cat5 (green and green/white). At least that would be how I'd try it at first.

It seems like real HDMI cables are done with shielded pairs, rather than unshielded ones, because each line has a plus, a minus, and a shield...so when you're using paired wiring you're going to end up just putting the shield wires off to themselves somewhere (and losing the benefits of the shielding, obviously).

Personally I think such a project wouldn't be worth it, considering the cost of cheap HDMI cables from China (via Monoprice), but don't let that stop you -- I'm sure it'd be an educational experience. Just don't do it in such a way the first time that keeps you from changing it, because you might get better results by playing with the pairings.
posted by Kadin2048 at 3:58 PM on September 5, 2007

Long digital cables are risky, since you can get bounceback with runs over 25'. Read about HDMI and long cables before you buy.
posted by Four Flavors at 4:07 PM on September 5, 2007