cabling confusion

Discussion in 'Archived Threads 2001-2004' started by Dennis P, Oct 28, 2001.

  1. Dennis P

    Dennis P Auditioning

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    Hello,
    I need some advice on home theater cabling. My TV is located on the other side of a doorway from my stereo equipment, necessitating running of the cables into the floor and across the basement ceiling, etc.
    The total distance is about 22 feet. What kind of cabling should I use and where should I buy it? My biggest concern is the digital audip output from my DVD player... it has both optical and digital coax. I've never seen an optical cable longer than 6 feet. Is this possible/advisable? If not, the digital coax will be fine... is there a recommended type of cable for that or will standard unshielded RCA-connector cable work?
    Thanks
     
  2. Selden Ball

    Selden Ball Second Unit

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    Selden
    Dennis,
    Digital audio cabling should be 75 Ohm coax, just like your video cables. It has to carry more than 1.5 Mbits/sec. It's probably a good idea to use that kind of cabling for your analog audio cables, too, to reduce their noise pickup.
    Some people like to use quad-shielded RG-6, but you don't have to spend a lot of money on "boutique" cables.
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    Selden
     
  3. Bob McElfresh

    Bob McElfresh Producer

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    You should use the coaxial digital connection and use ordinary CATV RG6 coax. Thats right, RG6 coax is 75 ohm so it exactly fits the specificiation.
     
  4. Dennis P

    Dennis P Auditioning

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    Thanks for the into.
    Where is a good place to buy RG-6, Radio Shack? Shall I buy the do-it-yourself connectors and crimp them on myself? I never had good luck in the past doing that with RF connectors for CATV...
    Also, I've heard some discuss "balanced" cables for long runs... what does that mean, and how do I do it?
     
  5. Selden Ball

    Selden Ball Second Unit

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    Dennis,
    My experience has been that crimping RCA connectors is somewhat more difficult than the type F connectors used on CATV cables. Radio Shack might be able to supply the cables you need. Or you might try contacting one of your local professional A/V suppliers. There are companies on the Web that'll make cables, too, but I have no experience with them.
    Balanced audio cables are only usable with preamps and amps which include the appropriate connectors and circuitry. Balanced connections provide much better noise immunity than the usual unbalanced RCA cables used in most home audio systems.
    They're 3-wire cables carrying a differential signal. One wire carries the positive signal. The second wire carries the same signal but with exactly the opposite polarity. The third connects to the cable's grounded shield. The receiving circuitry inverts the negative signal and adds it to the positive signal. Any external noise would have induced the same polarity signal on both wires. When one of them is inverted and added, it exactly cancels itself out.
    Balanced connections are used in professional audio equipment and very high-end home audio systems.
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    Selden
     
  6. Dennis P

    Dennis P Auditioning

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    THANKS for the thorough (yet concise) explanation on the balanced cables. I've always wondered....
    I guess I'll try to get a pre-built cable of the appropriate length at Radioa Shack or a local A/V place.
    Thanks again!
     
  7. Bob McElfresh

    Bob McElfresh Producer

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    Dennis: now that I re-read your post my question is: are you running long video and coaxial-digital cables?
    I know you said you were worried about the digital connection, but this is the least of your worries. Digital is much more robust than analog signals so long runs are much less prone to problems.
    My advice would be to place the DVD player near your TV, run short video cables to the TV and a long coaxial cable to the receiver for the audio. A 25' run of RG6 coax and RCA adaptors can be bought for $12 at radio shack. This is a LOT cheaper than a 20 foot run of component video cables and much less prone to problems.
    Good Luck.
     

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