Now we are starting to get into the more esoteric physics of an HDMI® cable. For many years, mainstream analog audio cable manufacturers talked about “Skin Effect” and how higher frequency’s tend to migrate to the surface of a cable and that lower frequencies stayed in the middle. As it turns out, there is some truth to this statement. Oh, not in the analog audio domain, that is still BS (in our opinion). However, in the high speed world of HDMI surface silver content and the type of dielectric do play a part in the performance of a HDMI cable. Now just throwing a thicker cost of silver onto the copper is not the complete answer. There must be a proper balance. Copper provides a stable high tinsel substrate for the silver plating, this will help the wire to keep its original length and shape which is necessary for the higher bandwidth and speeds (see #1 & #3).

Bandwidth and Speed are very important when discussing the construction of a HDMI® cable. One has to have a general understanding of how these two words pertain to cables as well as how they play into the cables functional capability. Bandwidth and Speed are a very difficult and confusing concept for most people to grasp.

What is Bandwidth? What is speed?

Although bandwidth and speed have much in common, they are different and are frequently and incorrectly used by both consumers and the manufacturers to express the same thought.

• Bandwidth refers to how much data can pass thru a device at the same point and time.
• Speed refers to how quickly a device can create the data.

The second part of this blog series we are discussing the two types of shielding and why they are important. The two types of shielding that a HDIMI cable should have to provide the best protection are braid and foil.

A braid shield keeps outside noise from interfering with your HDMI® cable by cutting down the 110/60Hz interference. If outside RF/EMI noise penetrates the HDMI cable it can cause all sorts of havoc. Since pretty much everyone has had some experience with HDMI Cat/x Extender failure due to high voltage switched devices (lights, motors, etc.) cause a short term dropout of the HDMI signal, there is an understanding of this issue.

Foil shield reduces the high frequency interference and keeps the noise within the cable. A foil shield also protects components from damage caused by spurious HDMI noise from running amok in your system like a gremlin. Foil shielding around the TMDS feeds of a HDMI cable also keeps the noise from causing problems with infra-red components and RF control systems.

We talk a lot about our cables while we are planning our displays for the CEDIA booth. Hours are spent grouping our cables together by category and the different technology they provide. I ask questions about each of our cables and when I started looking at my notes I saw these questions:

“What is the truth regarding HDMI and is there in fact a difference from one cable to another? Is there a reason to buy a better HDMI cable?”

In getting these answers, this blog post was born and over the next six weeks we are going to discuss the six parts of an HDMI cable and why customers should purchase a better (and preferably one of Metra Home’s) cables.

As most dealers know Metra Home has been a DPL member (www.dpllabs.com) since its inception. In our association with DPL we have learned that the vast majority of claims made about HDMI and HDMI cables are confusing and misleading. Metra Home has been fortunate to be associated with DPL and has over time received a reputation for good working, reliable and affordable products due to this association.