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What to Look For in Cables (cont.)

4. Build Quality

Cable Anatomy

The components that make up a cable can vary in quality. The materials and processing manufactures use help distinguish the difference between high quality and low quality cables. Below is a list of each component in a cable and what to look for information

  1. Conductor – For metal wires, there are three questions to ask when looking into a conductor. They are:
    • What material is the conductor made of? Silver is the best in conducting electricity with copper being second, and gold being third. Copper is by far the most popular due to its cheaper cost. Higher conductivity is determined by how pure the copper or silver is.
    • Is the conductor solid or stranded? There is minimal performance difference between solid and stranded wire. The only difference is that solid wire won’t bend as easy as stranded wire.
    • What gauge is the conductor? Small diameter conductors will have higher resistances than large diameter conductors. They also won’t pass as much current. Diameters are measured using the American Wire Gauge (AWG) standard where a lower AWG number equals a larger diameter.

    The shields in a cable are also considered conductors, and are used to carry the ground signals. The description above is meant to focus on one conductor that caries a signal. Digital cables such as HDMI and Ethernet will have multiple conductors inside a cable. Each of these multiple conductors are used to transmit a specific part of a signal.

  2. Dielectric – Dielectrics are used to isolate conductors from each other. Air, with a dielectric value of 1, is the best dielectric available. Unfourtantly, it is not feasible to build a cable with air isolating multiple conductors. To get a dielectric value as close to 1 as possible, manufactures will inject nitrogen or another gas into a solid. The most common solid materials that are close to a dielectric value of 1 are Polyethylene, Teflon, Polyethylene, and Polypropylene.
  3. Foil Shield – Look for cables that have foil shields to protect from any RF noise. Braded shields do not protect from RF noise.
  4. Braded Shield – Shields in cables are typically made out of copper or aluminum. Look for shields that cover at least 95% of the cable. The higher the percentage, the better. Although it is better to have two 95% shields than one 98% shield.
  5. Jacket – look for a well constructed jacket that protects all the inner components.
  6. Interconnect – once you know what type of video, audio, or data interconnect you need, make sure it is rigidly attached to the cable. Soldering of the interconnect to the cable should be done with professional guidelines to ensure solder joints are durable and free of defects or soldering debris.
  7. Contacts – What type of metal the contact is can affect how well the signal transmits to or from the cable. Gold plating on the contacts are useful since gold will not oxidize.

Note that fiber optic cables are all-dielectric, meaning they do not conduct electricity. Since they transmit light only, braded shields and foil shields are not necessary. Fiber optic cables can either be plastic or glass, with glass having more bandwidth than plastic.




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