There have always been debates about the differences that cables make and whether more expensive cables offer significant tangible benefits. In the days of analogue audio cables we have always reverted to the “trust your ears” approach. In our experience good analogue cables justify their existance by what they deliver and this is something that cannot be measured by analytical equipment.

If anything the debate over high price HDMI cables is even stronger. But it is interesting that with HDMI cables the differences are quantifiable and measurable.

The biggest problem with an HDMI cable is that when it’s bandwidth limitations are exceeded it simply stops working. This is because the receiving equipment is no longer able to accurately detect the 1’s and 0’s in the digital signal and gives up. Equipment does have error detection circuity that can detect bad data and to some extent recover the lost data but this is only effective up to a point.

Any given HDMI cable will have a maximum bandwidth or data rate that it can successfully work at. Exceed this and the cable fails to communicate. The longer the cable the lower this bandwidth is. So a 1.0M HDMI cable may be quite happy sending a 1080P video signal but a 10.0M HDMI cable of the same construction may not.

When HDMI cables are tested to see whether they work the results are presented as an “eye pattern”.

Here is an example of an eye pattern for a Wireworld Chroma 9.0M cable.

The purple pattern shows the signal being transmitted by the cable. The red lozenge outline shows an area that this signal needs to stay out of if the digital 1’s and 0’s are to be transmited successfully. If the purple pattern crosses the red line the cable fails. Equally the further the purple pattern stays away from the red line the greater the margin of success. A cable usually fails due to the red being crossed on the left side or the lozenge rather than the right side. This cable passes but only just. But to be fair to Wireworld it is the second least expensive HDMI cable in the range and in addition Wireworld only claim that the Chroma will handle 1080P up to 9.0M. But what we would like to see is tangible evidence that a more expensive Wireworld HDMI cable can do better. So lets look at the Wireworld Ultraviolet HDMI.

Here is a longer (and higher priced) 13.0M Wireworld Ultraviolet tested at the same bandwidth. Two things are imediately apparent. Firstly the purple pattern is much thinner showing reduced variation in the way the signal is transmitted. But most importantly the gap between the purple pattern and red lozenge has increased considerably. So this cable could be made up to longer than 13.0M and still be expected to pass. Actually Wireworld are very cautious and only guarantee the cable will do 1080P up to 12.0M.

So the superior performance of the Ultraviolet over the Chroma can quite clearly be measured. What about the relative cost? Well a 9.0M Wireworld Chroma is £140.00 and a 9.0M Wireworld Ultraviolet is £270.00.

One other issue that should be born in mind is that over time the bandwidth that you send over your HDMI cables may increase. So for example, you may
upgarde your screen from 720P to 1080P. But equally you may only be sending video over the HDMI but then start sending both the video and audio via an AV amplifier. So you may have an HDMI cable that works (but only just) and after the change the increased bandwidth exceeds its capabilities and it fails. The message here is that it is a good idea to get a better HDMI cable than you need today to build in some contigency for future upgrades.

We are grateful to Wireworld for publishing this data. It is quite rare for manufacturers to give access to their eye patterns.