Video vs audio cable

Discussion in 'Archived Threads 2001-2004' started by ArtG, Sep 24, 2002.

  1. ArtG

    ArtG Extra

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    Assume there is a difference between cheap and expensive interconnects and cables.

    Would there be a nontrivial difference between high-end cables designed for video and high-end cables designed for audio?
     
  2. Chu Gai

    Chu Gai Lead Actor

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    we talking interconnects here? if so one can use a video for audio, not necessarily true the other way around. for starters, with video you're going to want a 75 ohm cable.
     
  3. Bob McElfresh

    Bob McElfresh Producer

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    Let me ask you this: what is more sensitive: your ears or your eyes?

    If you give the obvious answer, you will see why you are more sensitive to problems with the video than with the audio.

    So this is why I feel you should buy good video cables before you buy expensive audio cables.

    (Also, audio has a lot of speaker placement issues, room interactions, etc that could negate the effect of a expensive cable. Video does not have as many variables.)

    The best quality cables I know about are the custom sites that use coax & connectors sold to the production studios. The studio that mastered your favorite movies did not go out and buy Monster/Nordst/Vampire cables for their professional quality equipment. They have a spool of Belden or Canare coax and a tech who custom-builds cables to send signals all over a studio.

    Check through some of the other threads and you will find the links to these custom sites.

    REALITY CHECK:

    I recommend the custom sites if you have a "sensitive" system - a system where the cable could make a difference. For a modest system, the AR brand from Best Buy, or even the cables from Radio Shack do a very good job.

    So how do you know if you have a modest/sensitive system? I suggest your system is "sensitive" if it has any of the following:

    - A display size greater than about 40 inches
    - A cable-run length greater than about 12 feet
    - You are pushing progressive or HD video
    - You are pushing ordinary video to a HD display that up-converts the signal.

    Hope this helps.
     
  4. Chu Gai

    Chu Gai Lead Actor

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    Hey Bob, just for fun and to point out that our eyes, and our senses in general, aren't necessarily all that wonderful and our visual perception depends upon many variables, take a look at this link
     
  5. Bob McElfresh

    Bob McElfresh Producer

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    Kinda cool.
     
  6. GregoryKrolczyk

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    Just goes to show how stupid I am - everything I've read says 75 ohm cables are the worst video interconnect.


    Live and learn.
     
  7. Bob McElfresh

    Bob McElfresh Producer

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  8. GregoryKrolczyk

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    Once again, my ignorance rears its head. I thought 75 ohm cables were the same as coaxial cables; the screw-on ones with the little wire in the center (F-connector type) that delivers the signal to your box. I also thought that the other types of cable - Composite, S-video, and Component - used a completely different type of wire. I didn't know that all three of those interconnects were also constructed out of 75 ohm cable.
     
  9. Bob McElfresh

    Bob McElfresh Producer

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    Greg: you are actually correct!

    Ordinary CATV coax is also 75 ohm coax. Both RG59 and RG6.

    So your next thought is: why cant we just buy a spool of CATV coax (at $0.20/ft) and use it for every cable that needs to be 75 ohm?

    Well, the impedence is not the only factor. (Impedence is kind of like the minimum requirement.)

    I dont want to expose my ignorance, so let me ask you to think of the asphalt in the street in front of your house.

    Now think of the asphalt on your nearest freeway.

    Are they the same? Yes. Does this mean you can drive 70 mph in front of your house? No.

    The roads are designed/built differently because they expect cars to travel at different speeds. But they tend to use the same asphalt for both.

    (I dont know if this is a good example.)

    Just realize that a cable company like Belden makes over 3,000 different types of cable. They have a specific type of signal/application in mind for each. They offer several flavors of cables for:

    - Audio
    - RF signals (CATV)
    - Ordinary Video
    - HD Video
    - DSS/Sat signals

    So you really want to use the coax for the signals it was designed for.
     
  10. GregoryKrolczyk

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    Actually, then, the question begs: If 75 ohm is so superior why do the manufacturers suggest you use anything but. Indeed, with DVD and HD hook-ups it's not even an option.
     
  11. Chu Gai

    Chu Gai Lead Actor

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    lot's of ways to skin the cat. maybe its because it's easier to obfuscate matters?
     
  12. Bob McElfresh

    Bob McElfresh Producer

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  13. Dan Pawlowski

    Dan Pawlowski Stunt Coordinator

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    I think Greg fell down the stairs[​IMG]
     
  14. John Royster

    John Royster Screenwriter

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    true, and impedance has little to do with audio interconnects (given the all over the scale impedance of the input outputs) problem with not having a standard I guess. twisted pair being better suited for this task.
     
  15. GregoryKrolczyk

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  16. Bob McElfresh

    Bob McElfresh Producer

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    The Interconnects are made with 75 ohm coax.

    Your CATV coax (with the screw-on "F" connectors) is also 75 ohm coax.
     
  17. Bill Street

    Bill Street Stunt Coordinator

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    I may be wrong, Greg, but I think you are confusing the R/F 75 Ohm cable with the screw on interface, with 75 Ohm cables that terminate in RCA, SVideo etc.

    If this is the case, the 75 Ohm cable is not the culprit. Using a standard CATV connection is considered the "less best" way to hook up electronics for a couple of reasons.

    One, the signal is carried by RF modulation, which means it must be demodulated to view, which adds another step in between the source producing the signal and what you're viewing it on.

    Two on an RF Coax connection sound and video is all clumped together. You get better quality viewing & listening by breaking up the signal into parts and giving each part a dedicated connection. Composite Video transmits one signal for video, S Video breaks the signal into two parts, and Component Video breaks it into 3 parts. Each of these is better because the signal is separate.

    Forgive me if I misread your post and you already knew all of this.

    Bill S.
     
  18. GregoryKrolczyk

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    Bill...You is my dawg! (That's a good thing.)

    Yes, you did indeed clear up my confusion (and save me a buttload of messaging).

    And you didn't even need to push me down any steps.
     

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