Blue Jeans Cable now offers active HDMI cables -- our Series-3A -- for those who need HDMI signals to travel over longer distances, from 20 to 50 feet, even when using the full bandwidth of HDMI 2.0.
We prefer to use passive cable products when passive cables will do the job, and our Series-1E and FE are still superb cables to use wherever that's the case. But HDMI data rates keep increasing -- each data pair in the cable, originally intended to carry signals up to 1.65/4.95 Gbps (HDMI 1.1), has been asked to do more with spec revisions -- first a doubling of that speed to 3.4/10.2 Gbps in HDMI 1.3, then a near-doubling to 6.0/18.0 Gbps in 2.0, and an upcoming double to 12.0/48.0 Gbps in 2.1. The difficulties of getting passive cable to work over distance increase with each increase in data rates, and while passive cable handled the 3.4 Gbps/pair signal well, and still handles the 6.0 Gbps/pair signal well up to 15 feet or so (our Series-FE Premium HDMI Cable certifications cover that), the longer distances called for in many home theater installations become increasingly chancy at 6.0 Gbps/pair.
The reason HDMI cable performance becomes increasingly difficult at these lengths is that between attenuation and return loss, the "eye" of the HDMI signal becomes harder and harder to keep open (see our other articles which discuss eye-diagram testing). Higher frequencies attenuate more strongly, and the sharp, rapid bit transitions required by higher bitrates become increasingly difficult to transmit because they rely upon extremely high frequencies traveling through the cable -- at 6.0 Gbps, the third harmonic of the fundamental frequency sits at 9.0 Gbps (fundamental being, for a binary-encoded digital signal, one-half the bitrate), and it's this harmonic which carries most of the energy of that sharp transition.
Up to a point, the answer to these problems is simply control over tolerances -- dimensional stability makes for better impedance stability and better-controlled return loss. But protecting the signal in this fashion can only do so much, because there are inherent physical limits one runs up against. After that point, the signal needs some rehabilitation to recover the sharpness of the digital transitions. An active cable does this by (1) amplifying the signal to compensate for attenuation, and, more importantly, (2) equalizing the signal to compensate for higher losses at higher frequencies. Because the sharpness of the bit transitions lies in the harmonics, this equalization is critical to restoring the signal to a condition where the receiving circuit will be able to read it correctly.
Older-generation active cables may work with 6.0/18.0 Gbps signals, but may not; the trick is that an EQ formula designed to deal with 3.4/10.2 Gbps signals may not perform up to snuff when dealing with the higher data rate. Our Series-3A cables use a chip designed expressly for the new 6.0/18.0 Gbps limits of HDMI 2.0.
The Series-3A cable draws its power for this amplification and EQ from the HDMI connection, so no external power adapter is needed to make it work. Usage is just the same as for any other HDMI cable, except for one thing: directionality. Because the cable is designed to take the signal coming in on one end, amplify it and put it out of its other end, these cables will only work when connected in the proper direction.
Series-3A HDMI cables are manufactured for Blue Jeans Cable by our long-time supplier, Elka International, who also have been doing the termination of our Belden-based HDMI cables for over ten years. We've gone to Elka with this project because we know, from long experience, that the quality of their work is outstanding. Their in-house engineering department is headed by Roy Ting; Roy participates in the HDMI Forum (who now write the HDMI specifications) on Elka's behalf, and we have had many consultations with him on HDMI engineering issues. Roy and his engineering department have tremendous expertise in HDMI design and quality control, and we know from experience that we can trust in the excellent quality of Elka products.
One little postscript: you may be reading this announcement and thinking, "well, but what about 2.1?" At this writing (August 10, 2018), the cable compliance testing spec for HDMI 2.1 has STILL not been written (some other portions of the CTS have been released), and until it's written and implemented by the Authorized Testing Centers, there will be no such thing as a properly certified "Ultra High Speed" cable meeting the 12.0/48.0 Gbps standards of HDMI 2.1. When that testing becomes available, and when compliant cables and chipsets are available to support it, we'll be getting new products out as quickly as we can; but for the time being, if anyone tells you he's got cables that meet these new standards, he's pulling your leg or, worse, trying to pick your pocket.