HDMI, A Brief Overview - How to Select the Right HDMI Cable for Your New HD TV or Home Theatre
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When shopping for a new HD TV or Home Theatre system often times how to connect it all up becomes the most confusing decision of all.
With the introduction of HDMI, the idea was to simplify connectivity between devices, and what a great step forward it is. Of course like most things there are some minor quirks but this technology offers mostly positive benefits.
HDMI (High Definition Multimedia Interface) means that a single digital link between source and display can now replace those numerous coloured RCA connectors that we were previously familiar with, or could more accurately be described as the Spaghetti Junction wiring lurking behind many a Home Entertainment System.
Besides the obvious advantage of less clutter, using a HDMI Cable means that you are able to enjoy a Full HD Digital Video signal (1920 x 1080 pixels) and uncompressed multi channel digital audio. Formats like Dolby TrueHD and DTS-HD Master Audio offer a soundtrack with flawless quality identical to the studio master.
Another important fact to consider is that S/PDIF connections like Optical/Toslink or Digital Coaxial do not offer enough bandwidth for High Definition audio. These connection types have a maximum data transfer of 1536kbps which is only enough for the legacy audio codecs like Dolby Digital, DTS or uncompressed 2 Channel LPCM (at a maximum resolution of 48kHz/16bit).
The potential quirks with HDMI technology usually stems from HDCP (High-bandwidth Digital Content Protection) handshaking issues or EDID (Extended Display Identification Data) synchronisation issues. Usually there are ways within the settings for each device to overcome any such issues. However, to cover this in detail would be another topic altogether and we may post another article in the future addressing these technologies in more detail.
So now you're out shopping for that nice new HD TV and you might be wondering what is required to set it all up?
Chances are that you came across some very expensive Cables and/or other accessories while looking for your new TV. The good news is that this article should help better equip you with knowledge so you don't end up spending unnecessarily for your new home entertainment setup.
Perhaps you have found this article after shopping at a local retailer and came home baffled why all the accessories cost so much. Well, the truth is they don't have to.
You might have heard that HDMI is digital so the cables are all the same. While this is true on a basic level, it isn't always as simple as that. Like anything there are still certain levels of quality that may impact performance.
Without strictly referring to HDMI Cables in particular but in general there are products out there that are insanely expensive. There are also products available that are just plain cheap and nasty. Best of all, there is great quality that can be found at the right price.
I am not about to tell you that every single HDMI Cable out there is a blatant rip off nor will I attempt to state that any low cost option is cheap and nasty. There are far too many variables to cover in regards to this. It is this happy medium (great quality at a low price) that I would like to concentrate on here in this article.
So what is the make up of a HDMI Cable? As a basic summary, a High Speed HDMI Cable with Ethernet, which is commonly referred to as a HDMI v1.4 Cable (even though this is technically the incorrect name and we will cover this in more detail soon) consists of 5 main separately insulated twisted pairs each with a drain wire and also four other separately insulated conductors. This makes 19 conductors in total. On the outside of these conductors below the PVC covering is a braided shield which usually also has another drain wire.
Most high quality Audio Visual Cables will use Oxygen Free Copper Conductors while cheaper Cables may use materials such as Copper Clad Aluminium (CCA) as this is generally cheaper to manufacture.
Probably the most important factor in regards to HDMI performance is the conductor wire gauge. What this essentially refers to is the thickness of the cable. This becomes quite important for longer lengths. Lengths over 5m start to have some impact. However, it is when lengths 10m and above are used that this becomes even more important. Electrical signals by nature will attenuate. This means that over longer distances the signal will gradually lose strength.
HDMI Cables will usually range from 30AWG to 24AWG. Some of the extreme budget varieties may use 32AWG (or thinner) conductors. It is also important to note here that a lower number equals a thicker cable. For example, 30AWG is the thinner conductor and 24AWG is the thicker conductor.
As a minimum 30AWG is usually ok for up to about 5m, 28AWG can be pushed to a maximum of approximately 10m, 26AWG can suffice for up to 15m and for anything over this length 24AWG is almost essential.
However, the above are bare minimums. For guaranteed performance, our recommendations are 28AWG for up to 4m, 26AWG for up to 9m and 24AWG for anything 10m or longer. Sometimes when approaching distances of 20m or greater, active solutions like HDMI Repeaters or Extenders are required as a passive cable may not be adequate. Please also note that these guidelines are based on today's technology. With rumours of 4K Resolution circulating (Ultra HD - 3840 x 2160 pixels), this would most certainly make the requirement for a quality HDMI Cable even more important.
The shielding of a HDMI Cable can also be quite important. However, this is a less complicated topic and basically any quality HDMI Cable should have triple layer shielding.
Please note that the above guidelines are only our recommendations and actual results may vary depending on the setup involved.
In regards to the different HDMI versions, previously HDMI Cables were referred to with version numbers. However, HDMI Licensing has now removed these and replaced the numbers with five categories. These are Standard HDMI Cable, Standard HDMI Cable with Ethernet, Standard Automotive HDMI Cable, High Speed HDMI Cable or High Speed HDMI Cable with Ethernet.
HDMI Licensing has certification standards in place and also offers a HDMI Adopter program. Any supplier of quality HDMI Cables should readily be able to supply the relevant certification on request. If you do happen to come across any that cannot offer this certification, our recommendation would be that you should be weary of the quality that might be on offer.
We hope this has provided some key points to help you get better value for money when shopping for accessories like HDMI Cables to go with that new High Definition TV.
Feel free to contact us if you have any further questions. We are more than happy to help with any questions relating to Home Theatre and Hi-Fi technology. You can visit our website via the link below in which our contact details can easily be found.
- David Burgchard (Space Hi-Fi)
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