OTHER TECH

Q. Does HDMI 1.3 improve on the rather anemic cable-run lengths that previous versions of HDMI supported? In my own case, I need a run of about 30 feet. Dave Ings Toronto, Ontario

A. GORDON SHACKLEFORD, Owner, Absolute Home Theater & Automation, Fairfield, IA, says: The HDMI spec doesn't define a maximum cable length, but as with all cables, signal attenuation becomes too high at a certain distance. Instead, HDMI specifies a minimum performance standard; any cable meeting that specification is compliant. In addition, higher performance requirements must be met to support video formats with higher resolutions than the standard HDTV formats. Different construction quality and materials will enable cables of different lengths.

HDMI 1.3 defines two categories of cables: Category 1 (standard or HDTV) and Category 2 (high-speed or greater than HDTV) to reduce the confusion about which cables support which video formats. Using 28 AWG conductors, a cable of about 5 meters (about 16 feet) can be manufactured easily and inexpensively to Category 1 specs. Higher-quality construction (24 AWG, tighter construction tolerances, and so on) can reach lengths of 12 to 15 meters, which would give you your 30 feet. Additionally, active cables (fiber-optic or dual Cat-5 cables instead of standard copper) can extend HDMI runs to 100 meters or more. Some companies also offer amplifiers, equalizers, and repeaters that can string several standard (passive) HDMI cables together.

I have used fiber-optic cables and amplifiers to extend cable lengths 50 to 60 feet with good results passing 1080p signals. But I'm extremely shy about using pre-terminated HDMI or DVI cables in my clients' walls. I much prefer using Cat-5 or fiber-optic cables in my installs, with appropriate termination adapters at either end of the run. This greatly relieves the stress of being left with a failed cable that cannot be re-terminated.

Read last month's Ask The Expert Back to Homepage What's New on S&V