How to setup my HDTV with HDMI cables?

November 30, 2007 8:09 AM

How much of a difference would using a 25ft vs. a 35ft HDMI cable make for a new 50" Plasma TV setup? Or should I go out of my way to keep it at 20ft or less?

To get my new tv (Hitachi, 50", 1080i, plasma) installed I'm having an electrician run some wiring to get things setup. I think the wiring runs will be around 20ft but don't want to cut it too close. After poking around online I was thinking I would order the 25 or 35ft hdmi cables from Monoprice.com
http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10240&cs_id=1024002&p_id=4033&seq=1&format=2

Or should I go out of my way to make the run be less than 15-20ft?
Also, does it make a difference between tin shielding or silver shielding? I'm no perfectionist when it comes to this so I'm not worried about the last 0.0001%, just want to make sure I have a clear signal
thank.

posted by Wallzatcha to Technology (8 answers total)

It shouldn't matter. If it passes HDMI specs, it should work.
posted by sanka at 8:47 AM on November 30, 2007

Since it's a digital signal, I think that all the differences in shielding are essentially meaningless, and I would bet that even 35 feet is a fine distance for a wiring run for HDMI. You can probably find the HDMI specs online somewhere.
posted by jcwagner at 8:50 AM on November 30, 2007

IIRC, standard HDMI cables should not be longer than 5 meters. I would dig around and verify that those cables will not lose any signal quality over that length.
posted by mphuie at 8:59 AM on November 30, 2007

Any suggestions on where I can find that info on signal degradation? I poked around in various sites before posting here and from what I've found it seems like the manufacturers tell you it degrades put individuals personal experience says that I wouldn't really experience a noticeable difference.
posted by Wallzatcha at 9:09 AM on November 30, 2007

This is the first hit for HDMI specifications cable length on Google:

http://www.hdmi.org/learningcenter/faq.aspx#connectors_cables

Looks like any cable that says HDMI has to be able to send the signal over its distance, so you should be fine with even the 35ft cables. Try to use the cable before it is in the wall, though.
posted by jcwagner at 9:26 AM on November 30, 2007

For a nicely in-depth article about HDMI and how it responds to distance, including a shoot-out type test between different lengths and price points of cable, I would recommend reading Gizmodo's 'HDMI Cable Battlemodo' here:

http://gizmodo.com/gadgets/hdmi-cable-battlemodo/

I thought they did a wonderful job of giving accurate judgements and tests about real-life and theoretical limits.
posted by AbnerDoon at 10:23 AM on November 30, 2007

With digital, it isn't so much that shielding doesn't matter, but that if it works, it works. Bits are bits, and if the bits get through, it will work perfectly. It there is too much signal degradation, the bits can't be read at the other end, and the transmission just doesn't work at all.

Of course it is a little more complicated than that.. In the old days of S/PDIF audio signals, cable depredation was probably a real problem. This was because re clocking data on the receiving end was hard and expensive, so jitter added during transmission could reach the DAC. Digital data transmission alone is robust to fairly severe jitter, (bits are bits). However, any jitter at all in the conversion to analog (sampling time uncertainty) will severely effect fidelity. Buffering data and re clocking has gotten a lot cheaper, so signal depredation in the cable has a lot less chance of effecting sampling time in modern audio systems.
posted by Chuckles at 10:50 AM on November 30, 2007

as a followup....
I ended up purchasing 30ft of hdmi cable, multiple hdmi jump cables and in wall hdmi connector plates from monoprice.com. I had a local electrician install everything, including an electrical outlet (still waiting on the bill).
I had them run a single HMDI cable from the corner of my LR where the satellite receiver is, through the attic and inside the wall to a plate behind the tv.
Everything turned out great and the picture quality looks perfect to me.

Here's a couple links to the monoprice.com items if anyone comes across the same situation:
30 ft. of hdmi cable
HDMI Wall Plates
HDMI Jump cables
HDMI Switch
posted by Wallzatcha at 7:14 PM on December 17, 2007