How to choose an HDMI 2.1 cable: a new standard, new problems | digital trends

Not so long ago, a good tip for choosing an HDMI cable was very simple: get an HDMI cable. Nowadays? Not much. Whether you’re about to set up a next-generation gaming console or build a major entertainment system, if using HDMI, you need to know that the game has changed.

And if you’ve already figured out that something has happened because you’ve had problems getting picture or sound on your new gear, you’ve surely landed in the right place.

I’m about to explain a little bit about why your new technology doesn’t work, as well as how to avoid running into this problem in the first place.

The old HDMI standard

In the recent past, my advice to people looking for guidance on HDMI cables was pretty simple. A bread-and-butter HDMI cable with lengths of up to 15 feet was almost guaranteed to work well. You may still be safe up to 25 feet. But then you’ll at least want to look at a cable with a lower gauge – bearing in mind that the lower the gauge number, the thicker the copper in the cable.

Basically, the longer you need the HDMI cable to be, the more you need to resemble a fire hose rather than a drinking straw, for example. Or you can switch to a different type of cable – but we’ll get into that a bit more below. Other than that, I wanted you to do your best to make sure you had good build quality and a strong connector on each end. Then there were the bonuses like higher flexibility for easier cable management or perhaps a color you prefer better than black.

For a long time, I was perfectly fine with most people who go with Amazon Basics cable For most practical uses for home consumers. As long as the cable wasn’t complete rubbish, it usually gets the job done. You’ll make it ones and zeros from point A to point B and you’ll get the picture and the sound. If you’re willing to spend crazy money on a high-end cable in the hope that you’ll get a little better audio and video quality, beat yourself up.

Now, things are different. In the world of HDMI 2.1 – or more specifically, the world in which new HDMI cables are supposed to be able to handle 40 to 48 Gbps of bandwidth (which is much more than the 18 Gbps standard we had before ), all bets are off. Well, not all of them, but enough to cause some problems.

Today, if you buy a cable that’s supposed to handle up to 48 Gbps with lengths between 2 and 3 meters (about 6 to 9 feet), odds are pretty good that any type of cable you buy will work. With lengths longer than that (and in fact, any shorter than that too) you’re more likely to run into some problems.

HDMI 2.1: What has changed

At the heart of the issue of why old cables are no longer enough is a cross between the high bandwidth or speed of information we’re trying to push down the chain of tubes in an HDMI cable, the construction of the cable itself, and a host of complex math and physics. The bottom line is that there’s a lot more going on inside an HDMI cable than you think. Most people I’ve spoken to are of the opinion that we’re talking about digital signals – ones and zeros – and that because it’s a digital process, it should be very simple and there’s no real difference in quality in the output of one HDMI cable and another.

To some extent, this is true. The signal being delivered is digital. But the way it’s delivered has a bunch of pretty analog factors.

Take a look at this infographic that I borrowed from a YouTube conversation between Jeff Boccaccio at DPL labs and Jason Dustal in Murideo. As you can see below, there’s a 5V line, a hot plug, a display data channel, some video channels, and then at the bottom, a clock – all the individual lines inside one HDMI cable.

The breakdown of channels inside the HDMI cable, as shown in HDMI 2.1
Jeff Boccacico / DPL Labs

I don’t know about you, but this graph shows me that there’s more going on in an HDMI cable than I thought.

This is a huge simplification, but the 5V channel on top has to negotiate a very specific slope between a source, like the Xbox Series X, and a receiver, like a TV or A/V receiver, just to get the party started. If this little thing doesn’t happen, nothing will happen. And while this trigger had fired fairly successfully in the past, it is now much more difficult. I’ll get to why in a moment.

On the other side of this chart is a clock. Without getting into what the watch actually does, it can be likened to working as an air traffic controller. If this watch can’t do its job, forget about it – there is no audio or video signal going to the TV or AV receiver. If the watch has tripped, you will likely see the audio and video signal go down in and out.

As demand increased, this tolerance decreased. And now we’re seeing more failures than we’re used to.

There are other factors like HDCP, EDID, and CEC that must be successfully digitally negotiated before audio and video can be sent down the pipeline as well.

So, where am I going here? You mentioned that higher speed or higher bandwidth was a factor. The more you try to increase the tube size, the greater the demand for tube capacity. The bottom line is that demands are now up with 4K resolution at 60 fps or more, with HDR metadata, and uncompressed audio – if the copper in the cable isn’t strong enough and isn’t strong enough in the right-hand side places for a certain length of cable Failure is imminent in a way that it has never been before.

Requests were lower in the past, so there was more fault tolerance. As demand increased, this tolerance decreased. And now we’re seeing more failures than we’re used to.

The longer the HDMI cable, the better the cable must be built, or the more need to move to a different type of cable that’s not just a bundle of thin copper inside.

So, what if you buy a cable that says “HDMI 2.1”, “8K Certified”, or “48 Gbps Guaranteed”? Then this cable should work, right? It says “certified” right on the packaging. Well, in a perfect world, yes. ought to. And in the short term, that’s likely to happen. But all I can say is that we hear about a lot more failures than we are used to. This is the world of audio and video in which we live.

Zeskit Ultra High Speed ​​8K HDMI Cable.

And it’s not just the cables, but the source and receiver devices that we use. These are also changing. It’s an evolving situation, and based on conversations I’ve had with some people in the industry who are knowledgeable… It’s kind of a mess, and it’s getting messy.

What are you looking for

So, what do we look for when buying HDMI cables that will reduce the risk of something going wrong? And if something goes wrong, what do you do? First, buy from a reputable retailer so you can get a refund or exchange for another product. Save your receipts!

Second, when you get your cable, plug it in and stress-test it before you do anything else. Play in 4K / 120Hz or do whatever you want from your most demanding audio and video system. Do this before you carefully route the cables and move equipment back and forth at hundreds of pounds. If it works, great. If not? throw it away. This should protect you from learning the hard way that your cable isn’t working, and you should be able to address the issue relatively quickly.

In terms of choosing an HDMI cable, all I can do is try to point you in the right direction.

Keep in mind that the following tip is for people dealing with 4K, high frame rates, HDR, and next-generation consoles — that kind of advanced stuff. Or, if you’re someone who just wants to future-proof as possible. If you’re installing an old PS3 or laptop, you’ll be fine with most suitable HDMI cables on the market today.

copper cable

First, you’ll be safer if you don’t buy a standard copper HDMI cable shorter than 1 meter or about 3 feet. If you do, there is a chance that the watch I mentioned earlier may not work and the cable may fail. So even though it may be longer than you think you need, you’re safer by starting at a meter.

From there, don’t use a standard copper cable longer than 2 metres. I’ll get to other types of cable in a moment, but make sure the cable between 1 and 2 meters can handle 48 Gbps, and buy a cable from a brand you trust. I won’t name the brands here, but if you haven’t heard of the brand before – well, it might be fine, but you take a risk. Make sure you’re okay with taking this opportunity and be prepared to take it back if it doesn’t work out.

Also, don’t buy the cheapest cable, and don’t buy anything expensive. The good stuff is somewhere in the middle. Really expensive cables are probably quite reliable but it’s probably overkill. However, the notion that anything other than the simplest of cheap cables is snake oil is not true.


If you’re going to be running an HDMI cable that’s more than 2 meters long, or about 6 feet, I think you should consider using an HDMI active optical cable or HDMI AOC very seriously. You might get away with running copper cable longer than before, but it’s a huge risk now.

HDMI AOC is a hybrid that uses optical fibers for some functions and copper for others and is a safer bet for long runs. How reliable is HDMI AOC in a 40Gbps world? We are still trying to determine this but will update this article as soon as we find out. I can say that if the HDMI AOC cable does not work, there is another step for longer operation.

HDMI cable type power cable with USB power connector

HDMI power cable

This will act as an HDMI power cable. There are two uses for the HDMI Cable Power feature. Currently, most devices don’t have an HDMI Power Cable built in, so the HDMI Power Cables you get will come with a separate connector that delivers power via USB, for example. But in the future, as more devices support HDMI Cable Power, you’ll be able to start using HDMI Cable Power cables without this little connector – the power will be transferred to the HDMI cable connector itself. If the HDMI AOC does not work, then the power of the HDMI cable must be.

One more important note. If you’re talking about in-wall use, you need to make sure that – on top of everything else we just discussed – the cable is rated for in-wall use. This usually means that it has a special jacket on the outside to prevent the spread of, or in some cases, the cause of a fire.

I understand there is a lot to take in here, but I hope this explanation and guide was helpful. As usual, I will update this article as new information is provided.

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