HDMI Cables
Dear Gary:
I am in the process of selecting a 35-foot long HDMI Cat. 2 1.3 cable to run alongside my trusty Comprehensive Video RGBHV cable from my source rack/cabinet to my projector, and so your HDMI articles in Issue 127, January 2008 were quite timely. Unfortunately, the articles do not point out the basic flaw in the whole HDMI architecture––twisted pairs (no matter how many you pack in one snake), are NOT good transmission lines for VHF/UHF/L-Band signals. In particular, no one I’ve seen sells a passive, HDMI 1.3-compliant cable longer than about 20 feet, because of the basic bandwidth limits of the three twisted pairs. That, sports fans, is not the end of it––wait until we all want HDMI 2 (680 MHz bandwidth per wire). Straight Wire’s Stephen Hill’s advice to run LARGE conduit or “smurf” tubes in your theatre cable routing is well taken, because when that day comes, we will all be replacing what we can buy from any of the vendors you have listed NOW, with something new.
The best long-term solution I have seen appears to be fiber-optic cables, with optoelectronic coupler/converters on both ends. These are available from the professional broadcast market starting in the $450 range at lengths from 50 up to 330 feet, and have several times the bandwidth of anything made of copper. The big issue with these is feeding the ~1.5-inch diameter heads through your wall and/or ceiling.
What is frustrating though, is how expensive the whole HDMI cable business has become, when more solid engineering upfront could have made everyone’s life much easier. For instance, the 100-foot-long RG-6 cable that connects my satellite receiver to its LNB on the dish, has a bandwidth of OVER 1.5 GHz!! A SINGLE multiplexed RG-6 cable, (with, perhaps, a groundline to handle the HDCP handshake signal), could handle HDMI 1.3 bandwidth requirements, and two, in parallel, would handle HDMI 2. The best part about RG-6 is its price––one can buy 100 feet of Belden RG-6 terminated with good F-connectors at the local hardware store for less than $35. Why this was not the approach chosen for HDMI is beyond me, and leads me to believe, (like almost everything else in this crazy business), that greed and licensing fees have had a lot more to do with home theatre standards than value for the customer. One need only look at the battles over HD audio, (DVD-Audio versus SA-CD) and HD video (Blu-ray Disc versus HD DVD) to see where the industry’s REAL
priorities lie, and it ain’t with providing the consumer with low-cost solutions for anything. Speaking of value, I would urge your readers to look at the HDMI, DVI, and RGBHV cable offerings available from the professional broadcast market––they are excellent products at excellent prices and represent solid engineering. Three vendors worth considering are Monoprice, Comprehensive Video, and Gefen.
Finally, Widescreen Review needs to investigate the whole issue of HDMI cable-induced jitter and its impact on audio DACs. I have heard anecdotal evidence that it is much worse than our old friend, S/PDIF, which has presented jitter problems in the past. I suspect a comprehensive look at this subject will lead to a complete re-examination of the suitability of HDMI for digital audio, and, consequently, where the DACs should be located for good sound (i.e., player versus processor).
Thanks for your excellent articles, and I am looking forward to the next installment.
Don Bingaman
Managing Editor Danny Richelieu Comments:
Thank you for your comments, Don, and great idea for a future article on HDMI-induced jitter. I, too, have heard it is worse than S/PDIF, and it is an issue that will need to be addressed in the future.
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