Ok, a bit of a report this.... sorry! But I've been frustrated by the lack of science behind Stuff magazine's preaching on the topic of HDMI cables. They recently did offer up some welcome science, hence this report.
Summary
Stuff magazine's view on HDMI leads is to buy expensive leads for your home entertainment system (see p251, January 2009). I disagree with this. After testing various cables 2 metres in length on a standard living room set-up, I noted that the differential in image quality offered by the cables is either unnoticable or non-existant. I conclude from this symptom that the limited electromagnetic conditions and the minimal length required for HDMI cabling in our homes causes the majority of us no reason to purchase expensive HDMI cabling.
Testing
To prove to myself that I wasn't just adopting a cynical attitude towards professional gadgeteers telling us that cabling is far more important that we might think for digital signals, I took the opportunity of playing two Blu-ray versions of The Dark Night on two separate PS3's plugged into two HDMI inputs on the same HDTV (Samsung LE40A756). I was able to do this by chance really; I took my PS3 to my brother's house for christmas where we had duplicates of the key components.
There was one difference in the twin set-up: the HDMI cable. My brother got talked into paying £70 for the cable, the salesman iterating time and again that its silly to spend £800 on a TV but not get a high quality cable (but he could not explain the science as to why the expensive cable should perform better in a living room scenario). I actually brought two cables with me: a £4.99 cable purchased online and a £9.99 cable bought at gamestation. All 3 cables were 2 metres.
We played the movies simultaneously with exactly the same picture settings for both HDMI channels on the TV and with both PS3s set-up identically.
After testing the £9.99 cable against the £70 cable, I repeated for the £4.99 cable against the £70 cable.
Test results were observational in form. My two brothers and our girlfriends were witness to this geek-ridden event. We compared the cables by switching HDMI channels on the TV with an obsessive desire to spot any differences. Comparisons and up-close inspections were made of freeze-framed images, slow motion playback, playback in film and TV native frame-rates, picture extremities (image reproduction in low/high contrast and in low/high brightness etc.) and we also fiddled with the TV and PS3 picture processing software.
Results
Nothing. Everytime we flicked from cheap to expensive cabling the picture was no different (both were fantastic, I couldn't see how the picture could be better). Not one of us in the room could see a single, not a single difference. For what its worth, the sound was no different either (but of course this would need to be tested on a proper surround sound set-up).
Conclusion
Signal degradation (digital data-packet loss) in a HDMI cable of two metres or less does not occur to the extent necessary to warrant high-end materials and their associated cost. Perhaps for a 10 metre a cable the extra shielding and build quality is necessary. But for your standard home set-up? No, definitely not. It's also worth mentioning that the TV used for this test would be considered awesome just 12 months ago, and Stuff has been proclaiming the virtues of expensive HDMI cables for longer than this - hence to say that a higher-end TV would spot any differences would be erroneous. Furthermore, with TV's coming down in price, expensive HDMI cables are becoming a larger percentage of cash spent on a decent set-up, so my view is this: please please don't tell people to spend more money than they need to for results they will not get. I felt my brother got conned by a salesman who probably didn't even mean to con him!
Stuff, remember that science is beautiful but the magnitude of forces and the context in which they're exerting has to be rigourously verified: think Coriolis effect and the water-swirl myth.
I'm spent! Feel free to contradict or agree with me people, I love all that!
