Cable Question: Did I Get Ripped Off?

Discussion in 'Archived Threads 2001-2004' started by John B. Holbrook, Jan 28, 2002.

  1. John B. Holbrook

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    OK, on E-Bay, I bought a cable with the following description:

    THUNDER CABLE 6' DIGITAL COAX VIDEO CABLE NEW

    The description goes on to say that this digital coax cable can be used for either audio or video.

    What I got looks to be what I call a standard RCA video cable, not a digital coax. The package says:

    THUNDER VIDEO CABLE RCA CONNECTORS

    I'm requesting a refund, but the seller says that an RCA video cable can in fact pass a digital audio signal. This doesn't sound right to me, but the jack size is the same. Should I get the refund?????
     
  2. Kevin Coleman

    Kevin Coleman Second Unit

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    No they are pretty much one and the same. As long as it is a good 75OHM video cable with decent RCA connectors it should work great for digital audio.
    Kevin C. [​IMG]
     
  3. John B. Holbrook

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    Hunh. Don't I feel stupid. Then tell me this: is it pretty much a toss up as to which is BETTER: Optical or digital coax?
     
  4. Bob McElfresh

    Bob McElfresh Producer

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    On the optical vs coaxial debate, they are in theory identical. But reviewers HAVE heard differences in some optical cables, but very little difference in coaxial.

    This leads to the thought that coaxial is more consistant (and robust).

    Someone bought a Radio Shack and Monster optical cable and tried shining the output onto a piece of paper and comparing the 2 cables. The Monster cable was much brighter for the same source. This reinforces the conclusion that coaxial cables are "better".
     
  5. Rob Roth

    Rob Roth Stunt Coordinator

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    The real trick is getting true 75 ohm termination. IMHO, the cable gurus are right when they say an impedance mismatch will cause signal reflections in the cable with time distortions the consequence.
     
  6. Phil A

    Phil A Producer

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    It will work fine as far as passing the signal but I would not make a broad generalization that cables desgined for video will necessary be the best for passing digital audio. Yes, a constant and stable 75 ohms is an important factor, but so it velocity of propagation. Also, it is somewhat dependent on the components used. Some things are just more sensitive to changes than others not necessarily better or worse.
     
  7. Bob McElfresh

    Bob McElfresh Producer

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    As long as we are getting into details: [​IMG]
    At lower frequencies you usually dont have to worry about reflections caused by impedence mismatch. The higher the frequency, the more of an issue it becomes.
    Your DVD puts out about a 500Khz bit rate. Even doubling this for safety means the cable needs to handle a 1 Mhz signal.
    I think NTSC video has a maximum frequency rate of about 12 Mhz.
    So the "ordinary video cable" is expected to handle frequencies about 10 times faster than what your DVD will put out.
    This is why I think an ordinary video cable can handle the DD digital signals without much reflection problems.
    And the last I looked, "Velocity of Propagation" IS an issue for coax, but more for CATV companies who are running hundreds of yards of cable across town with ANALOG signals. It's effect on a 6 foot cable carrying DIGITAL signals is likely to be minimal.
    This is why I think an ordinary video cable can always be used for the coaxial-digital connection.
     
  8. Mark Rich

    Mark Rich Second Unit

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    Yes, if the cable you received is a 75ohm cable then it will work. How it will sound will depend on the make-up of the cable. Center conductor, insulation, shielding, connectors etc..

    Not all digital coax cables sound the same. I just switched (once again) my digital cable to the new RhinoCables digital coax cable. Most noticeable improvement in the bass area. I can now identify bass lines and individual drums more eaily. Great performance, construction and now on sale. Love it!
     

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