Tuesday, December 6, 2011

HDMI extensions

My whole house entertainment system features video from several sources (DVD Player, Dish box, Harddrive recorder) run through HDMI to displays in Kitchen (where all the distributed video sources are), bedroom, and living room.  Two long HDMI lines are run with OWLink fiber optic HDMI to bedroom and living room.

This had worked well for about two years until a month ago the HDMI link to bedroom stopped working.  After a bunch of tests, including swapping the receiver with the one in bedroom, I decided that the Kevlar-wrapped optical cable (run outside the house from kitchen to bedroom) had gone bad, probably when housecleaner stepped on it.  However, that turned out to be wrong.  Instead, it turned out that, for no apparent reason, the optical transmitter in the kitchen for the bedroom link had gone bad.  When I swapped that for the other transmitter (used for living room), bedroom worked fine.  Since the bedroom link is more important (used every day) I keep the good transmitter running on the bedroom link.

OK, so now my best evidence suggests that one of my two OWLink transmitters has gone bad (it blinks, while the receiver LED stays constant, a typical OWLink failure mode).  But even that is not certain after last week, when I tried to switch my good OWLink transmitter over to the living room link.  THAT did not work, so I had to use a temporary workaround for my party (I used my Oppo BDP-95 for the DVD, normally I only use that player for audio discs).

So now that it seems I have misdiagnosed the problem twice, perhaps my second set of OWLink components is actually still working, or needs something trivial like a new power adapter.  But I wouldn't count on it.

If it still works, the optical link is worth keeping.  It has one very beneficial extra feature: it does not introduce any kind of ground loop into the related systems.

Meanwhile, I've been looking at new options.  Getting a new OWLink setup is one of them.  But rather expensive and hard to find (possibly even the 3 or so websites that still claim to have them are sold out).  Until today, the lowest price seemed to be $599, but today I discovered I could get one at digitalconnection.com for a mere $399.  That's still awfully high, but still worth considering.

Other alternatives:

2) CAT-5,6,7 based HDMI transmitter and receiver (CAT-7 said to be best)
3) 2 30 foot copper HDMI cables and a relay
4) Other optical system

There are many varieties of (2).  Some of the (very expensive) ones use only one CAT5,6,7 cable.  Using just one CAT5,6,7 requires some subtle multiplexing.  Most of (2) use two CAT5,6,7 cables.  I've now found one as cheap as $70 available at Amazon.  I'm worried that if shielded twisted pair (STP) wire is required, the shielding could introduce a ground loop.  Official specs say that STP should be grounded on both ends through the connector (there is no ground pin on CAT5,6,7 wiring).

3) Here's a relay available at digitalconnection.com that permits two HDMI cables to be joined.

4) I've seen some other optical systems priced as low as $299 for 10m, $499 for 20m.  Typically the transmitter/receiver modules are permanently attached to the cable in the cheap sets, and detached in the more expensive sets, which can go up to $1500 (and I thought OWLink was expensive).  Detached is better, since you could replace cable w/o replacing the adapters.

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