Tuesday, October 27, 2015

Construction of a HDMI Cable Part #6: Testing Procedures



If you have made it this far in the series you have seen how important each part of the cable is at least in our option. The real question is, how can this be validated as truth and not just be set aside as the ramblings of a PR/Marketing department?

Let us return for a moment to a contributing factor in what triggered this series, http://www.cnet.com/news/still-more-reasons-why-all-hdmi-cable-are-the-same/ and http://www.cnet.com/news/4k-hdmi-cables-are-nonsense/. The issue here for us is the testing methodology, all that was done to verify the quality of a given cable was (A) borrow a tone generator/scope and sweep/Eye pattern test one channel at a time of the three video channels and (B) plug the cables in between a source and a display. This is not a good or accurate way to test as timing of the 3 channels together is critical and without this concurrent channel testing results will be skewed.

So, how can you know if a cable is worth a damn?  DPL testing that’s how.

In theory, any cable that has the HDMI logo on it has been tested and approved by HDMI LLC.
We all know of course that this is not true (I have seen cables being sold at a price that is lower than the HDMI license fees). As evidence to this just before CEDIA 2015 HDMI LLC announced a new “Premium” certification program.  Apparently the previous “HDMI 1.4 High Speed” certification did not prove to be robust enough of a test to verify and validate the actual bandwidth needed to properly support the HDMI 2.0 feature sets. Also, in the past month was the announcement that “Underwriters Laboratory” was getting into the cable performance testing game.  Now to be fair both of these entities do an acceptable job of high speed video performance testing, unfortunately since each assumes that the bare minimum ATSC test for EDID is good enough neither one push’s the envelope for low speed data.

So “Meh”. Well who can you trust?

For Metra Home Theater Group it is again DPL (Digital Performance Labs), they are recognized as the strictest and most quality consistent testing facility in the AV world. A cable that can show and prove the DPL Seal of Approval is a safe choice for your installation. As mentioned before this could all be a line from marketing but time and many participating companies have proved that DPL knows what they are doing and can be trusted to tell you the truth. If you have any questions about a cable line or length go to http://www.dpllabs.com/ and check on that product. If it is not there ask yourself why.

What does this have to do with cables?

As mentioned in a previous installment of this series, DPL certification is neither quick nor cheap.  First, it takes a while to design and build a cable that meets the DPL standards. Second, in order for DPL to maintain “truth in testing”, ongoing testing is required.  DPL does not get these samples from the vendor instead DPL purchases them from dealers and/or distributors to test what is out in the field.  So like “UL” certification DPL has a yearly fee to keep you (the vendor) up to date.  For the dealer this is a fantastic resource as well as a great and timely report of what is tested and real.

We hope you enjoyed this blog series – if you have a suggestion on another topic please comment below.




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