Are Active (HDMI) Cables the Future?

With a recent tear-down by ArsTechnica on the new Thunderbolt cable Apple is selling for $50, we're starting to wonder if active cabling is the future of all A/V electronics. With a desire by content providers to keep everything digital and protected in the realm of high definition television, and A/V manufacturers scrambling to provide features that will generate more 'oohs' and 'awes', it's a wonder if we aren't digging a hole.

A great big hole.

It all started with HDMI. When it began, it was buggy. but sending 1080p over multiple copper wires was still feasible. As the HDMI Licensing Group began to feel pressure from organizations and formats such as VESA's DisplayPort, however, the race began. New features, like Ethernet support and Audio Return Channel (ARC) began to emerge, as did support for uncompressed multi-channel audio in multiple native formats and, most devestatingly in our opinion, ultra-high video resolutions.

Now, I'm all for high resolution, but is the consumer market really in need of 4K × 2K (3840×2160p24/25/30Hz and 4096×2160p/24Hz) resolutions? Can't digital theaters use something more demanding and consumers be left with something that's actually manageable?

This week, ArsTechnica's tear down revealed that the new Thunderbolt cable form Apple costs $50 largely because it is active. There are two Gennum GN2033 Thunderbolt Transceivers embedded within the cable at both ends. And this isn't the first time we've seen active cabling. When DVIGear began to make its 22 gauge Blue Super High Resolution HDMI cables we immediately wondered how many consumers would want to deal with cables that looked like they were meant to be used as towing harnesses rather than A/V interconnects. But that's the problem with ultra high resolution, and now HDMI 1.4a and Category 2 specifications... you need to support an inordinate amount of bandwidth over long distances.

We've espoused What's Wrong with HDMI before, but we're now wondering if we've just hit a wall. If, from here on out, even shorter runs of HDMI are going to more or less have the requirements of being active in order to support the bandwidth needed for future technology and throughput.

That certainly seems to be the writing on the wall. And it's going to add costs to cables that are already expensive if you don't know where to shop. If Big Box stores can charge monstrous prices on passive cables, can you imagine what will happen when they all go active?

In order to avoid cables that are ridiculously thick and heavy, manufacturers are more consistently turning to active HDMI cable technology. But it has to be done correctly. Even HDMI argues that it's a recommendation (that's an understatement!) for longer runs and that relying on the built-in 5V line isn't the most reliable way to do it (again, yet another short-sighted failing of the HDMI spec). The trouble is, many of these solutions require an external device or at least a power source - that's another black box you need to add to your install JUST TO RUN A CABLE FROM ONE PLACE TO ANOTHER. In their own words:

Using active electronics to boost and clean up the signal can effectively double the range of a standard twisted-copper HDMI cable. Cable runs of up to 30 meters are the norm for this type of solution, which may be deployed as either a standalone signal management device, i.e., a repeater or booster box, or incorporated into the manufacture of the cable itself. Boxes are available in many configurations, usually incorporating both booster and equalization functions, and may also serve as repeaters or switchers. Active cables, on the other hand, embed the signal-enhancement electronics in the cable itself, with chips embedded in the connector housings. They are unidirectional, using different modules at the transmit and receive ends of the cable. All the technologies in this category require external power.

Beware products that draw power from the +5V power line. Although these may work in certain applications, different components draw varying amount of power from that line to communicate with each other. A cable that draws power from the HDMI cable may fail when components and the active components in the cable or external booster are all drawing from the same source.

So what can we expect? A switch to all-active is the spec keeps changing to accommodate more and more things most people don't use in their home theaters. If HDMI continues to increase resolution capabilities and adding features - and electronics manufacturers keep supporting them - then those copper cables you have simply aren't going to cut it in future products.

Fortunately, electronics keep shrinking. That means more and more electronics can fit into smaller spaces. One of the things we hate about embedded electronics is that it often makes the connector heavier, longer, and more difficult to manage. Since HDMI doesn't inherently have a locking mechanism, connectors are already prone to fail. Adding more weight certainly doesn't improve things. Smaller chips will yield smaller connectors - and this is a good thing.

The problem of power is also still an issue. Since the 5V available over HDMI is often not enough to power the active electronics - especially over longer distances, external power seems to be a constant requirement. We're not sure how this will be improved over time, but that's the current elephant in the living room, and it's a big one. Nobody wants to plug HDMI into their receiver and then supply it power just to get to the projector.

It would also be great for the industry to realize that there is a lot of work left to do in terms of 1080p, and that expanding to higher resolutions is inappropriate for the consumer market. Separating the commercial and consumer markets might actually make a lot of sense and keep needless advances from trickling into the spec and applications where it's just not needed.

What do you think? Are you pleased with the current state of A/V and HDMI cabling? Do you want to see more active electronics coming to the consumer market? Or do you think that the added expense in cables is going to make it harder for consumers to get what they need and wire up their rooms - especially over longer distances.