The Truth About HDMI Cables


History
It used to be the case that when buying decent home theatre equipment and high end hi-fi gear, you needed to think very carefully about the cables connecting it all together. There were all sorts of things to consider and choose between to make sure you got the best out of your brand new TV or Speakers. Companies spent a lot of money researching ways to improve the cabling – higher gauge, more strands, gold plated connectors, better shielding from interference etc etc.

There was an element of truth behind it all in that when audio and video were transmitted in analogue form (ie. a waveform – think sine wave), the signal travelling in the cable was very susceptible to noise and interference. This caused the signal to degrade and become noisy, resulting in a loss of clarity at the receiving end – especially over longer distances. Your picture may not have been as sharp and crisp as it should be or your audio may not have been as clear as it should be. Using better quality cables helped rectify some of these issues, though not without cost. Higher end cables cost considerably more than the basic options – though put side by side, it was often possible to see or hear the difference and so this outweighed the cost. With the theory there to support the technology, it made more sense.

Examples of analogue connections include:
– SCART
– RCA
– Component – YPbPr (though this is a ‘High Definition’ interconnect, the signal is still transmitted in analogue form)
– Wire connection to speakers

Digital Connectivity
Fast forward to today where most, if not all new current home AV systems are digital or have an option to use a digital method of signal transmission.

Examples of digital connections include:
– HDMI
– SPDIF
– Optical

For anyone that is even slightly technically minded, they will know that digital is all about 1’s and 0’s. Either on or off. The signal that is sent down these cables is sent in 1’s and 0’s in varying ways depending on the content that is being transmitted.

Now this is where a bit of logical thinking comes in.

With your old analogue signal, if it deteriorated a little bit due to bad quality cable, that part of the information was lost. However, if the ‘1’ in a digital signal is affected by some noise and gets a bit weaker by the time it gets to the other end, it is irrelevant. The receiving equipment will still see it as a ‘1’ (as long as the interference doesn’t cause it to drop below the threshold) and thus the signal received is exactly the same as the signal sent. There is no loss, noise or degradation.

In a round about way, what this means is that for most general applications, in terms of functionality, a cheap HDMI cable will do exactly the same job, and will do it to exactly the same standard as a HDMI cable costing several times as much.

Footnote
This is not the end of the story, however – there are some instances where buying a slightly more expensive (‘slightly’ not ‘ridiculously’) is worth it.

1. The REALLY cheap and nasty HDMI cables are not built as well and the internal wiring or even the housing for the connector may be prone to breaking. The better built, more expensive cables will usually be up to taking some heavier abuse.

2. As I mentioned there is a threshold at which point a digital ‘1’ or ‘0’ may not be explicitly clear to the receiving piece of equipment due to interference or signal degradation. For a digital signal, in a typical home environment, this would likely only happen when using cables over long distances. It is probably worth getting a slightly better quality cable for longer distances (>5m) or very (electrically) noisy environments.

Basics HDMI Cables of varying lengths:
REALMAX® 1m 2m 3m 4m 5m 10m HDMI Cable High Speed Gold Premium Quality supports all HD ready devices and gadgets (2m HDMI Cable)


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