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Thursday, April 18, 2024

Still more reasons why all HDMI cable are the same

HDMI cables don’t have numbers!

Even after two articles, and a tremendous number of page hits, there still seems to be lots of questions about HDMI cables. I credit this to the complexity of the topic and the mountain of misinformation out there, rather than any particular failing of the writing on my part. Judge as you see fit.

But the fact is, a recent reposting of my original article lit off a bevy of new questions. Instead of expanding on that already bloated article, I figured a new one would be a better idea.

On to 3D, 1.3/1.4, getting physical, and more…

There is no such thing as a ‘HDMI 1.4 cable’
A “1.4” cable is a big misconception, and stems from truly terrible monikers from HDMI Licensing. There are two aspects to HDMI: the cable and the connection. The cable is dumb, just passing along whatever data you give it. The connection is where all the features are. There was a big push when 3D came out that you needed HDMI 1.4 to do 3D. This is true, but “1.4” is a connection spec, not a cable spec. Any high-speed HDMI cable can transmit 3D.

It’s probably worth mentioning outright and again that you do not need a special HDMI cable for 3D. And if you want to get really specific, 3D on Blu-ray isn’t a higher frame rate on the disc, it’s technically a higher resolution. Wrap your head around that one (or not, it’s explained in “How 3D content works: Blu-ray vs. broadcast”).

The exception is Ethernet over HDMI. If you’re one of the few who have equipment that features Ethernet over HDMI, you will need a specific HDMI cable that supports it (it’ll be labeled as such).

Bottom line: “HDMI 1.4” has nothing to do with cables, it refers to hardware (TV, Blu-ray player, etc.) only. So says HDMI.org. There are only four HDMI cable types: high speed with or without Ethernet, and standard speed with or without Ethernet. As you can get high-speed cables for less than a cup of coffee, just get those, with or without Ethernet as you see fit.

Long cables/cables with chips
Throughout the other HDMI articles, I advised getting the cheapest HDMI cables you can for short runs (under 10 feet or so). As HDMI cables get longer, though, they start running into trouble (more on this in a moment). I’ve tested regular HDMI cables over 50 feet, and the results were mixed. With some source/display combinations, I got an image. With others, I got sparkles or no picture at all. Enter active HDMI cables.

Some HDMI cables have chips built into them that help boost the signal. One example of such a chip is RedMere. I reviewed one of their reference designs (they license their technology). Matt Moskovciak reviewed a 60-foot Monoprice cable with RedMere. Refreshingly, it makes no claims at all about better picture or sound quality (or other such nonsense). Instead, the company says simply that its technology allows for either really thin HDMI cables (spaghetti-thin) or really long cables. There are other active HDMI cables on the market, too, so it’s worth checking around if this is something you think you need. Remember, though, the 60-foot Monoprice cable Matt reviewed works and is only $76.88.

Bottom line: If you need to run long HDMI cables (33 feet or more), it’s probably worth considering an active cable. The price difference doesn’t have to be substantial. Or consider wireless…

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Wireless HDMI
We’re starting to see more wireless HD devices on the market. Price-wise, these can’t compete with HDMI cables, but they’re a lot easier to install (obviously). Current versions of the technology are still a little quirky. They work with little or no degradation in the image. However, the Wireless HD standard, running at 60GHz, doesn’t work well through cabinet doors (and sometimes not through people, either). Other versions work over the same 2.4GHz wireless spectrum that your Wi-Fi and cordless phones use, so there’s potential for interference issues.

Bottom line: HDMI cables are cheap, even long ones. Don’t want to run cables across your room or through walls? Wireless is an option, albeit an imperfect one.

There is no linear correlation between signal quality and picture quality
One of the most common (and vociferous) rebuttals I’ve received in the previous articles’ comments is from people with some knowledge of how electrical signals are transmitted over copper wires. They say, correctly, that all signals over any cable degrade with distance, and can pick up noise from external sources. This is true, but show a lack of understanding how HDMI signals get transmitted over cables. Even though I did explain why HDMI acts differently than analog video/audio transmission, it’s clear it was lost in too much science-y stuff. I’ll use this chart instead:

This looked way better in my head (and thanks to people commenting below for making it better). With Analog, as the signal quality decreases, the picture quality decreases. With HDMI the picture quality is perfect, up until there isn’t enough signal to create an image. Then you get nothing. If you’re right on the ledge, you get sparkles.
Geoffrey Morrison

HDMI transmission is a technique called transition-minimized differential signaling. I discuss this at length in the original article, so I’ll just sum up here. TMDS is very robust, and means that even if the signal is very weak, or picks up noise along the way, the 1s and 0s get received by the display exactly as they are in the source. As the signal gets worse and worse, the picture/sound quality stays exactly the same. It’s perfect picture/sound up until it simply isn’t. If the signal is too weak, you get sparkles or nothing at all. Or, as I said in the header, the correlation between signal quality and picture/sound quality is not linear. It can’t be. The packets of data that represent pixels of video don’t degrade. If there is not enough signal, they simply cease to be. It is an ex-pixel. Beeee-reft of life. It is. No. More.

I guess that’s the part that people get hung up on. Decades of understanding with analog cables is a hard thing to shake, and I’m just some punk on the Internet telling you you’re wrong (check my sources).

Bottom line: HDMI signal quality has little to do with picture/sound quality.

‘Well built’
I’ve said before that for long cable runs, it doesn’t hurt to get a “well-built” cable. But what does that mean? Some cables have thicker, more rugged jackets, stronger plugs, etc. Some can have better internal wiring that ensures that there’s less degradation between source and display.

It does not necessarily mean more expensive, however. In fact, I’d say there’s little if any correlation between price and build quality. I’ve used cheap cables that were well built, and expensive cables that felt cheap.

If you’re going to run your HDMI cable through a wall, or have it lying on the floor like I do in my otherwise pristine lab (yeah, right), a strong jacket is beneficial. For most people, though, even cheap cables will be fine.

There are also downsides to “expensive” or overbuilt cables. Some manufacturers, in an attempt to make their expensive cables seem worthwhile, have thick, heavy plugs. These are horrible, adding strain and wear to your components. I’ve heard stories from readers complaining their heavy HDMI cable dislodged the HDMI input on their display.

There’s little to prove “better built” cables will last longer, either. And even if cheap cables don’t last as long, who cares? Sure, the $60 cable has a lifetime warranty. But do you really think you’ll need to replace a $3 cable 20 times to justify that price difference? If you think so, well, there’s nothing I can do to help.

Bottom line: Some HDMI cables are built better than others, but this is likely a superfluous distinction. There will be no difference in picture/sound quality, though over long runs maybe you’ll be more likely to transmit a signal (check out active, instead). Even if a cheap cable fails, you’ll save money in the long run replacing it rather than buying an expensive cable to start.

‘I had a problem with my cheap HDMI cable, so I bought an expensive one, and the problem went away’
This is a pretty common complaint, and the second half of it is usually a conclusion of: “Therefore, cheap cables don’t work.” However, this is a logical fallacy on multiple levels. It’s possible to get a bad cable, or have a cable not work with the equipment you have (if you’re dealing with really long distances). The better test would be to buy another cheap cable, and see what happens. This will likely fix the problem (or try one of the other methods listed here).

Bottom-bottom line
I don’t regret calling my first article “Why all HDMI cables are the same,” but boy did people take that literally. There are benefits to better-built cables, or active cables, but these benefits have nothing to do with picture/sound quality. The image is either perfect, or it’s not an image. Other than sparkles, there is nothing in between.

I know this won’t be my last article about HDMI cables, but if I’m honest, I love talking about them. Too many people have gotten ripped off for me to stop now.

(So check out the HDMI cable buying guide and 4K HDMI cables are nonsense for even more HDMI cable info.)

Got a question for Geoff? First, check out all the other articles he’s written on topics like HDMI cables, LED LCD vs. plasma, Active vs Passive 3D, and more. Still have a question? Send him an e-mail! He won’t tell you what TV to buy, but he might use your letter in a future article. You can also send him a message on Twitter: @TechWriterGeoff.

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