One question about cables please everybody read.

Discussion in 'Archived Threads 2001-2004' started by Jason-Pro, Jun 21, 2002.

  1. Jason-Pro

    Jason-Pro Stunt Coordinator

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    Ok !
    ive been looking at all the insides of my cables (taking off the little twist cap on the RCA cables.

    and the digital coaxial cable is the same as the Video cable and all the other cables. they both have one wire on the outside and one wire on the pin. what is the true difference between these all ??

    and the component cables i didnt look at (but im buying one) and it looks like they would use the same cable.

    please help me out id like to know (just curious)
     
  2. John Royster

    John Royster Screenwriter

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    I believe most 75 ohm video cables are of the co-axial line (share same axis). This means a single solid wire with another cylinder of wire around it.

    Digial coax cable is the same. Component is a 75 ohm coax cable so it is the same design as well.

    Audio intereconnects usually are a twisted pair and can vary in impedance from 50-250 ohms I think, but that seems to be changing with some manufacturers using coax as well.

    I'm sure somebody more knowledgible can chime in.

    AFAIK twisted pair and coaxial are the most cost effective means of reducing noise and interferance. Add some shielding (foil) around the cable and it is pratically bulletproof.
     
  3. Phil A

    Phil A Producer

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    Shame on you looking under RCA plugs. What is this world comming to? Digital cables (unless they are of balanced design with XLR connections in which case they are 110 ohms impedence) are specified as 75 ohms, the same as video cables. So while you can use a 75 ohm cable for either, there are certain characteristics they may have that may make them perform better for one function than the other, including such things as RG-6 vs. RG-59 (size of conductor difference), solid center wire vs. stranded, material of the center wire, velocity of propogation, shielding, no. of shields, dialectics used, etc. The above is not an all inclusive list.
     
  4. Jason-Pro

    Jason-Pro Stunt Coordinator

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    oh i see
     
  5. Phil A

    Phil A Producer

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    Also, if you go to the 'Hardware for Sale/Trade' section, Vince has very generously offered to make cables for material costs only so you may wish to take a look.
     
  6. Bob McElfresh

    Bob McElfresh Producer

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    Jason:
    You can buy coax cable (that all looks the same) in 50, 75, 110 and 300 ohm impedences. Audio cables can be made with any of these.
    As a Convention: all video cables are made with 75 ohm coax.
    When they were coming up with the specification for the coaxial-digital connection on a DVD player, they decided to use the common-as-dirt video cable: 75 ohms.
    Your CATV and DSS coax is also made with 75 ohm coax.
    But dont get the idea that they are ALL interchangable.
    It's like asphalt. Its the same stuff is in front of your house and on the freeway. But that does not mean you can drive 60+ mph in front of your house. You build it for the speed you intend to drive.
    (we can get into this detail later if you want. [​IMG] )
     
  7. Chu Gai

    Chu Gai Lead Actor

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    and if you build it, they will come.
     
  8. Jason-Pro

    Jason-Pro Stunt Coordinator

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    ok thanks for the help
     

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