HDMI/DVI cables...

[Nuz]

Hi all,

I been reading various reviews on HDMI/DVI cables and a lot of people say it's a hype paying a ton of money for certain brands. I've read as long as the product have successfully completed ATC Compliance Testing in accordance with the HDMI Compliance Test Specification at the HDMI Authorized Testing Center and HDMI DIGITAL signals cannot "lose signal strength" nor can they drop the quality of your picture since it's digital.

http://hdmi.org/consumer/faq.asp

I'd thought I'd ask you AVS'ers to see how true it is...

I came across this site: http://www.puredigitalhome.com Just cancel on the language prompt.

Nuz

[oddjob]

For short runs of say 6 feet and less, the cable is not going to make much difference. For longer runs, the real world problems seem to be not with the TMDS signals (the RGB digital video) but instead with the DDC signals. These are I2C format signals with passive pullups and the cable capacitance will slow and skew the signals. Longer cables - more capacitance. HDCP runs over the DDC connection, and also that's how the source gets to learn about the display resolutions.

I can't get my Vidikron M40 to run with a 25 foot cable to a nvidia graphics card in my HTPC, and the DDC signals are the problem. Several chip makers have active I2C buffers that accelerate the I2C rising voltage transitions, intending to negate the cable capacitance. But they don't seem to work very well.

There is a market there for a very low capacitance cable, or an active cable that buffers the DDC lines (maybe even transceive DDC and use a robust transmission scheme internal to the cable rather than I2C).

I'd be interested to hear of others success, or failure, in running 25 feet and longer DVI or HDMI cables.

[spillz564]

I run a 10m (or 33 ft) DVI cable from my Momitsu V880 to a projector with no problems. I can't remember exactly where I got the cable but I can dig up the link if requested.

[oddjob]

[QUOTE=spillz564]I run a 10m (or 33 ft) DVI cable from my Momitsu V880 to a projector with no problems. I can't remember exactly where I got the cable but I can dig up the link if requested.[/QUOTE]


Video card DVI (nvidia, ATI, ...) appear to be the worst for driving long cables. I have better luck with my Toshiba SD-5980 (HDMI).

[dsmith901]

You may find this helpful:

http://bluejeanscable.com/articles/digitalanalog.htm