The most important thing you need to realise about interconnecting cable is that the role of any cable whether it is
Ethernet, Speaker Wire, Fibre-optic, Digital Coaxial, Coaxial (RJ-6, RJ11, etc), Component, S-Video, Composite video,
RCA, etc, is to get the signal from sender to receiver. No interconnect, whether it is made of aluminum, copper, silver,
gold or even fibre-optics has 100% signal transfer. Also, in absolute terms no cable will enhance, improve, increase,
boost, (or any other adjective the marketing wordsmiths can come with) the signal, in any way, shape or form.
There is a continuous debate in Audio / Video magazine, internet forums and probably at your local AV store about
interconnects; the liveliest debate is usually about speaker wire. So we are going to steer clear of the speaker wire
debate and all other wire debates and focus our attention on one thing, HDMI. At this point in time with everything
going digital in AV (save speakers), HDMI is the connection of choice for your A/V interconnect needs. HDMI is not immune
to the lively debate. That debate always turns to the issue of cost, performance and value. The wire that you
ultimately choose, costs what is costs, so we will steer clear of that topic. As for value, value is perceived by the
individual(s), so I am going to leave that one alone. So that leaves us with the issue of performance. By performance
I mean how well the HDMI interconnect gets the signal from point A to point B. Luckily for us, HDMI cables carry data,
and are very similar to Ethernet cables used in IP networks everywhere. Ethernet cables have gone through a lot of scrutiny,
and has commonly accepted beliefs on what affects performance. So here is what you need to know.
There are a number of factors that can affect an interconnecting cable’s ability to efficiently carry the signal from
Point A to Point B. The conductivity of the conductor material that carries the signal, the length of the cable, the
quality of the material used to insulate the cable, and finally the quality of the connector end and the quality of the
connection of the conductor to the ends.
The purer the copper the better
Good conductivity is important to allow electrical current to flow more easily without resistance through it.
Copper is the material used as the conductor material in interconnects due the fact that it has a high conductivity,
compared to the other common materials that are used. The purer the copper the better conductivity you will have.
The only time that this would not hold true, is if the only impurity in the copper is silver (silver is actually
more conductive than copper). Some wire manufacturers combine silver with copper to make up the conductor
Keep your cables as short as possible
All material no matter how conductive does offer some resistance to the flow of electrical current, so the
electrical current traveling through the conductor is just like you climbing a hill. The longer and steeper the
hill, the less energy you have when you get to the top. So keep your interconnecting cable as short as possible,
as there are other things working to keep the signal from getting from A to B.
Look for polystyrene (good) or polyethylene (better) conductor insulators; also look for Teflon and/or aluminized Mylar
and/or copper braiding as shielding.
To provide a high definition picture, a lot of data must be moved along the HDMI cable; the higher the
resolution the greater the data. To move a vast amount of data across a cable in a small amount of time,
you have to move it fast; the more data the faster you have to move it, which causes a phenomenon know as
the “skin effect”. As the speed of current flow increases, the current flows move from the core of the
conductor to the outer surface of the conductor. Some current on the outer surface of the conductor does
not reach its destination as it is absorbed by the insulation material. Unfortunately, no insulating
material provides 100% resistance to the flow current, so some of the signal wanders into the insulation
and get lost. Technically speaking, the best kind of insulation is a vacuum, and then air would be next
in line. Using a vacuum or air as an insulator is not practical for home use, even in 2008, and the next
best insulator semi-solid dielectric is not currently being used. Next in line is foamed dielectric.
You will find foamed dielectric used in some HDMI cables. What are typically used as insulation in most
HDMI cables are solid dielectrics. Generally, solid dielectrics that surround conductors are plastic
composites, with polystyrene (better) and polyethylene (best) being the superior materials. Teflon is
actually considered the best solid dielectric, but I don’t think you will find it being used in HDMI
cables; unless it is being installed in aircrafts.
Trying to keep the signal you want in is not the only insulation challenge; you also want to keep
unwanted signals out. EMI (Electro-magnetic interference) is also a problem, and it is attracted to the
conductor material. EMI causes unwanted noise to arrive at the receiving end of the wire along with the
desired signal, and if the noise level gets too high it may drown out the signal. If you have even been
in a night club, and tried to have a conversation standing next to the loud speaker, you understand what
I am talking about. You probably had to repeat parts of your conversations several times, to be heard
and understood. Even though it is aggravating, your message is eventually received and understood by
the recipient, or you just move away from the speaker and continue your conversation. Your interconnecting
wire can’t do that; it can’t just pickup and move to a quieter environment. With digital data in an IP
network, having to repeatedly re-send data is not that big of a deal (the IP protocol actually allows
for that); things just run slower, or things arrive out of order and are re-assembled before it is rendered.
With real time sound and video that is a problem. You can’t really wait for re-sent information to arrive.
The sending device just keeps sending data at its output rate, and the wire and the receiving device just
has to keep up. So when the signal the receiving device needs does arrive in good enough quality, you get
no or garbled sound, see frozen images, a blank screen, or a bunch of little squares.
Look for Teflon, Mylar foil and copper braiding to surround individual data channels to stop individual
channels from interfering with each other, and to keep external EMI from entering the signal path. Better
cables will use those materials and other techniques in combination to block as many different frequencies
of EMI as possible.
Look for gold connector ends as they have the best surface to surface conductivity
The ends of your interconnecting cables make the connection to your devices. To allow you to easily connect
and disconnect cables, the connection between cable end and device is of the surface to surface type. Gold has
the best surface to surface conductivity, so you will typically find gold connector points on your better AV
components and your better HDMI cables. The connection between the connector ends and the conductor is also
of critical importance. Unfortunately you will have no way of inspecting this aspect of the cable you choose.
The internet can help you with this; try a few searches on your chosen cable to see if there are frequent
report s of cables that mysteriously stop working without any change in equipment or setup. This is an indication
that the conductor and connector ends have a tendency to separate.
Another issue to be aware of with HDMI, if you are using heavily shielded cables that are heavy and bulky, be
sure to use some kind of strain relief near the cable and device connection. Due to the current design of the
HDMI cable to device connection, heavy cables have been known to cause the cable / device connection to become
loose or separate completely.
There is a silver lining with HDMI cables that you should know. Analog signals degrade gracefully; the range
from superb signal to unusable signal is relatively wide. With the digital data that HDMI cables carry the
range between superb picture and sound and no picture and sound is very narrow, so you will know pretty quickly
if your HDMI cable can't cut the mustard. Just look for any signs of pixilation or moments of no picture when
you put your HDMI cable into use. One other thing! If you have a momentary blank screen when you change channels
using your set-top cable or satellite box connected to your HDTV using an HDMI cable, it is not an indication of
a poor cable. It is the way most set-top boxes function. I mention this only because I encountered someone who
got a new HDTV, HDMI cable and set-top cable box, and they assumed that the problem was the TV or the new
Finally, here is a link you should checkout before you purchase that discount cable. The link will take
you to Simplay HD website,
where they keep a list of products including cables that have been Simplay HD verified (if you don’t know about
Simplay HD, read this article). The list doesn’t provide
specific information like the category of cable, data throughput rates, or devices that the cable is best suited
for, but at least you have some assurance that the cable length list can get your signal from A to B.