The Plain Truth About HDMI Cables

Does the type of cable connecting audio and video components together matter? There has been a long standing debate surrounding audio/video (AV) interconnect and speaker wire. The debate is usually conducted in the audiophile /videophile community, with high-end cable manufacturers and their supports making claims of improved performance, and the naysayers claiming that a cable is a cable, is a cable. Recently a journalist doing a story on HDTV, conducted tests on HDMI cables and came to the conclusion that all cables (or at least all HDMI cables) are alike. I had heard about this report, but had not actually seen it; I found it first on YouTube, which led me to the original video.

The cables ranging in price from $12 no name cable to $262 Monster Cable Ultra cable, were tested using testing equipment and humans viewing a televised hockey game to see if there was a difference in the picture quality delivered by the cables. The result of the viewer test and signal testing equipment both showed that there was no difference in the quality of the signal delivered under the test conditions. So people who buy the more expensive cables are just buying “snake oil”, right?

The answer to the aforementioned question is yes, and no! It is obvious from the 9 minute video that the goal of the “investigative” reporter was to prove that there is no difference between expensive cables and low cost cables, and she succeeds. Everything (almost) that is stated in the report is true to the best of my knowledge. The only statement made in the video that was not 100% truthful came from Maxine, the TV station Production Engineer. I certainly hope that he was reading a scripted statement (towing the party line), and not making what he believes to be factual statements. The statement was “... the cable is not degrading the signal in anyway”.

If you know anything about wire, you know that Maxine’s statement is not 100% accurate! Some will argue that I am splitting hairs on this one, by the simple fact is no wire is capable of achieving 100% signal transfer! There is a thing called resistance (or electrical impedance to be more precise) that causes the signal you put in the wire at the sending end to not come out exactly the same at the receiving end. Even if you use the wire that has the best signal transfer characteristics, (which is fibre-optic cable for data transmission), 100% of the signal does not make it through the wire. The difference between what is sent and what is received may be infinitesimal, but infinitesimal or not, the signal always degrades, and that is the factual truth of the matter.

What the reporter was trying to make consumers aware of, is that you should do your research before you go shopping. Doing so will stop you from being charmed by a snake oil sales pitch from sales people who lack the knowledge to answer your questions properly. The really amusing thing is, if the reporter had followed her own advice and researched HDMI technology, she may have conducted a real test, instead of the stilted version conducted in her story.

The 12-bit Panasonic DMP-BD30 output data rate exceeds Standard Speed cable requirements

Before I get to why these tests are stilted, here is the quick low down on HDMI cables, (click here to read a background article). We are currently at version 1.3 of the HDMI standard. Under the original version 1.0 standard (way back in 2002), cables had to have a data throughput rate to efficiently support a 720p/1080i signal (about 2.23 Gbps) at minimum. Along came 1080p, Blu-ray and the now defunct HD DVD, doubling the required data rate to keep things moving, and suddenly problems started for some early adopters. Your chosen cable and length may not work with the new thirsty component. If you are using a short cable you didn’t have a problem, because it may work, or you at least have access to it to replace it. If you had a long cable, perhaps as part of a custom install before the drywall went up, you have a big problem.

The chart above shows the data rate of typical AV source devices and the type of cable you need to support them. It also illustrates why the tests conducted in the news report were artificial at best. What the Journalist and her colleagues tested is equivalent to testing whether a 5 ton dump truck does a better job than a 1 ton pickup truck at getting a ½ ton of garbage to the dump. O.K., bad analogy, but you get the point. There are 2 levels of certification for HDMI cables, standard speed or high speed. Standard speed cables have been tested to handle a 1080i resolution, and the highest resolution you can get from cable or a satellite set-top-box… you guessed it, 1080i. So the hockey game test was a test of nothing, the low cost cable meets the standards it has been certified to meet, and the Monster cable is also a certified HDMI cable. The tests performed by Maxine is even more ridiculous; instead of using all the high power testing equipment with an 8 bit or 12 bit Blu-ray player, or a computer pumping out 2560x1600p at 60Hz, they used a low resolution DVD player!

So here’s the thing! If you are using an HDMI cable to hook your set-top-box to your new 1080p bedroom HDTV, and the cable connecting the two will be less than 15 feet, you can use just about any cable you want. When connecting AV equipment you must remember that the lowest common denominator determines what you see and hear. In the aforementioned situation, the set-top-box with its 1080i output is the limiting factor to what you will see on your HDTV. But also remember that electrical impedance plays a factor, so if the set-top-box and the HDTV are 25 feet apart, you may want to do your homework before you purchase that low cost cable. As a cable gets longer its ability to get a signal from Point A to B diminishes, so low cost cables may work, some may not. If you are hooking up a blu-ray player to your 1080p HDTV, and the cable will be 6 feet or shorter, you may be able to use just about any cable you want (the short cable lenght is your best friend).

If you are planning to build a home theatre room with in-wall wiring and you plan to purchase and upgrade regularly so that you always have the best Blu-ray player, HDTV, sound system, etc. that money can buy; then reach deep into your pocket and buy the best Monster Cable that is available at the time. You might be wondering why the plug for Monster Cable? 2 reasons. HDMI is a rapidly evolving standard; the transfer rate for new state of the art equipment will continue to increase. You don’t want to have a situation where your in-wall cable becomes the limiting factor, and you have to re-install. The labour and cost of the new HDMI cable will cost you more than the Monster Cable. The top-of-the-line Monster Cable exceeds the bandwidth requirements of commercially available equipment, so you have a little bit of a cushion. The second reason is Simplay HD (a subsidiary of Silicon Image) mentions monster cable in a lot of their PR stuff; so the two seem to have a rather cosy relationship. Silicon Image is listed as one of the founders of HDMI, but HDMI is actually Silicon Image’s technology. Silicon Image is a company that focuses on high-bandwidth semiconductors for PC/displays, consumer electronics and the storage market; wiring is not their area of expertise. So who do you think is providing the expertise on the physical interconnection cable side of HDMI? Enough said.

When you are ready to purchase your HDMI cables, your best resource is the verified product list at Simplay HD. Also, consider not only the price of the cable, but also ensure that you choose the correct category of cable to meet the needs of the equipment it will connect. If you want to know what makes HDMI cables perform better, read this article.

It would be nice if the Journalist did a follow-up story and used all their high power equipment to do some real meaningful testing, and published the results.