Cable quality suddenly becomes important

A while back I mentioned how I’d found Australian interconnect company, Kordz, to be a very good deal for HDMI cables. I first stumbled across Kordz in an article in Connected Home Solutions (for which I write), which was discussing cables. David Meyer from Kordz had been interviewed and was expressing concern about the quality of some of the HDMI cables on the market.

Naturally I reserved judgement. I could see the point that cheap cables may not carry the bandwidth to support full 1080p signals with multichannel audio, but I didn’t think that this would, in the end, be a real issue.

Well, yesterday I plugged a new Blu-ray player into my system. The signal was fed via a one metre Kordz cable, to a Kordz 5-way HDMI switchbox (the receiver I’m using doesn’t have HDMI switching), and thence via a 10 metre cable to a projector. Everything worked perfectly, even with a 1080p signal at 60 hertz.

Jaycar HDMI cable, left, and Kordz HDMI cableBut this afternoon I had to test the player with a same-brand high definition LCD TV, and it was more convenient to use a different HDMI cable to plug it in. I had a relatively inexpensive five metre one I had purchased a while back from Jaycar Electronics that I had used many times with 1080i signals, perfectly successfully. But when I connected the Blu-ray player to the screen and tried delivering a 1080/60p signal, the picture kept flashing bright white across the bottom, occasionally disappearing for an instant to be replaced by noise. The audio also dropped out.

So I switched the BD player to 1080i output, and everything was fine. Back to 1080p, and the problem was again apparent. I then swapped the cable for a three metre cable of the same make (the code numbers on the cable’s insulation were identical) and this worked fine at 1080/60p.

So there you have it: cable quality is very important with HDMI. With a cheap cable, even five metres is too long for the high bandwidth demanded by 1080p/60. The dot clock frequency for 1080/60p video is 148.5MHz, which gives an idea of the bandwidth required.

For the moment I’ll be sticking with Kordz cables.

This entry was posted in Cables, HDMI. Bookmark the permalink.

Leave a Reply

Your email address will not be published. Required fields are marked *