Funny story. I haven't purchased a new HDMI cable in a while, but the 30-foot cable that runs from my gear rack to my projector rack died on me awhile back. I was in no real hurry to replace it, since I've been using a DVDO Air3C-Pro wireless HDMI dongle to send satellite TV and 1080p Blu-ray between my sources and projector. Now that a Samsung UBD-K8500 Ultra HD Blu-ray player has joined the team, however, the lack of a wired HDMI solution is a problem. The DVDO dongle doesn't support 4K, you see.
So I headed to Monoprice.com to order a new cable. Knowing full well that I'll be dealing with a lot of 4K, HDR, and higher bit-depth content in my future, I chose to play it safe and get a cable from the company's more expensive Enthusiast Series, described as "High quality HDMI for premium 4K resolution." I went with the Luxe Series CL3 high-speed cable, which costs $42.99 for a 30-foot length.
When the cable arrived a few days later, I ran it between my Sony VPL-VW350ES 4K projector and Onkyo TX-RZ900 receiver, turned everything on, and got...nothing. Literally nothing. No blue screen or snowy screen to indicate a handshake problem. Just nothing. "Wow, what a spectacular failure this cable is," I said to myself.
And then I saw it. One word printed very clearly on the end of the cable that I had just connected to the projector: "Source." Hmm. I walked over and looked at the other end of the cable, currently being fed into my receiver, and it said "TV." Oh yeah, I thought, I bought an active cable, didn't I? Turns out, the spectacular failure was me. Unlike passive HDMI cables that are bidirectional so that you can attach either end to either device, an active HDMI cable is a one-way design. I turned the cable around, reconnected it, and everything worked fine. It just goes to show that, no matter how long you've been doing this hobby and how many different systems you've set up, the potential for user error never goes away.
I share this story not to humiliate myself, but rather to save others from similar folly. As I dutifully reversed my cable, it occurred to me that this isn't a topic we've ever really covered, even though active HDMI cables have been available for a number of years. In fact, the only time we really discuss HDMI cables is when we're debating whether or not premium HDMI cables are worth it. I'm not going anywhere near that topic today, but I will say that spending a little more money on an active HDMI cable versus a passive one can be a worthy investment for particular situations.
You probably already know that HDMI is most reliable over shorter cable runs. If your equipment rack is located just a few feet from your display, then a passive HDMI cable should work fine. As the distance between source and display increases to 30, 50, or 100-plus feet, reliability can decrease, and the cable needs a little "help." Manufacturers like Gefen, Atlona, Key Digital, and others have long sold standalone HDMI extender kits that boost the signal to improve reliability over longer runs.
As advancements in semiconductor technology allowed those chipsets to get smaller and consume less power, it became possible to place the HDMI signal booster in the cable itself, and that's what an active HDMI cable is. The technology really drew the spotlight a few years ago when a company called Redmere introduced an active chipset that not only allowed for longer runs, but also allowed the active cable to be much thinner, more flexible, and powered via the HDMI port itself. If you've ever tried to connect a long or beefy HDMI cable to the backside of a wall-mounted TV, you know the headache it can cause. Those cables don't bend easily. The emergence of lower-profile wall mounts only exacerbated the problem. Redmere cables were a welcome solution.
Monoprice was a major early proponent of Redmere technology, first debuting active Redmere cables with much fanfare in early 2012 (you can watch the company's original informative video here). Later in 2012, Redmere partnered with Fresco Microchip and Chrysalis Capital VIII Corporation to form a new semiconductor company called Spectra7, which continues to develop and manufacture the active chipsets under the new name. So, although the Redmere name is being phased out, the technology is still alive and well.
If you explore the active HDMI offerings that are currently available on Monoprice's website, you'll see that Redmere-branded cables are still available. These are older, legacy cables, many of which support a 10.2-Gbps bandwidth to pass 4K/30 at a distance of up to 100 feet. Newer active cables like the Luxe Series CL3 cable that I purchased use a newer Spectra7 chipset that supports the full 18-Gbps bandwidth needed for 4K/60, 16-bit color, and 4:4:4 subsampling. The Luxe Series is available in lengths up to 100 feet but only promises support for 4K/60 up to 50 feet. (By comparison, a passive HDMI cable supports 4K/60 at a length of 20 feet, at best.) If you need a really thin, flexible HDMI solution for a shorter run, the Ultra Slim Active Series also uses an 18-Gbps chipset and has a 36AWG conductor, but it maxes out at just 15 feet. Obviously the cable you choose would depend on both the length you need and the type of video signal you want to send.
Of course, Monoprice isn't the only cable manufacturer that sells active HDMI cables. Most of the major names in the cable business offer active HDMI options, especially at longer lengths. For example, all of Wireworld's flat HDMI cables--from the entry-level Island 7 Series to the premium Platinum Starlight 7 Series--employ active technology in lengths from 30 to 65 feet (the Island 7 Series uses active technology starting at 23 feet). Transparent Cable offers two active series for cable runs of 30 feet and longer: the Performance Active Series includes 30- and 50-foot cables, while the High Performance Active Series includes lengths of 30, 40, 50, and 65 feet. Monster Cable offers active options like the UltraHD Black Platinum 4K Cable that's available in lengths from four to 35 feet.
Active HDMI may not be the right choice for every installation. If you require an extremely long run or need very flexible cable to snake through walls, a solution like HDBaseT, which runs over Ethernet cable, may be a better choice. However, for those times when you need a clean, easy way to run a high-bandwidth 4K/60 signal around your room and/or your mounting solution demands a very thin, flexible cable, active HDMI is definitely worth a look. Just make sure you learn from my mistake and check the cable orientation first--especially if you're planning to run that cable through a wall or snake it under a carpet!