Digital Coaxial cable?

Archived from groups: rec.audio.pro (More info?)

Can you use a 'regular' left or right composite cable to make a coaxial
connection or do you have to get an actual coaxial cable? I wasn't
sure if the coaxial cable was wired or made differently inside then the
audio composite cables were.

Thanks.
7 answers Last reply
More about digital coaxial cable
  1. Archived from groups: rec.audio.pro (More info?)

    Sseadoubleyou wrote:
    > Can you use a 'regular' left or right composite cable to make a coaxial
    > connection

    Please explain what you mean by this? A standard sheielded audio cable?
    That's a coaxial cable. "Coaxial" means that there are two conductors
    that share the same axis along the length of the cable. There's the
    center conductor, and the shield around it.

    > I wasn't
    > sure if the coaxial cable was wired or made differently inside then the
    > audio composite cables were.

    Depending on what you're connecting, you may need something other than
    the RCA connectors that you're familiar with, if I correctly guess what
    cables you're talking about. There are many coaxial connectors (as well
    as cable types), of which the RCA phono plug, the most common audio
    connector in consumer products, is just one.

    There are all sorts of ways that a cable sold as a digital interconnect
    cable might be better than your plain old RCA audio cables, but you
    won't hurt anything by trying what you have avaiable. For short
    lengths, just about anything will work.
  2. Archived from groups: rec.audio.pro (More info?)

    "Sseadoubleyou" wrote ...
    > Can you use a 'regular' left or right composite cable to make a coaxial
    > connection or do you have to get an actual coaxial cable? I wasn't
    > sure if the coaxial cable was wired or made differently inside then the
    > audio composite cables were.

    You appear to believe that "composite audio cable" and "coaxial
    cable" are two different things. In 99.8% of cases, they mean
    exactly the same thing.

    Some people may use "coaxial" to mean RF (or video) style
    ("RG") cable, but that is the kind of language perversion and
    imprecision that is causing your confusion.

    Furthermore, for most short (<4ft) consumer digital (S/PDIF)
    applications, resonably decent shielded ("coaxial" or "composite"
    if you will) audio cable will likely perform perfectly as well as
    them most expensive botique snake-oil cable you can find.
  3. Archived from groups: rec.audio.pro (More info?)

    Sseadoubleyou <Sseadoubleyou@yahoo.com> wrote:
    >Can you use a 'regular' left or right composite cable to make a coaxial
    >connection or do you have to get an actual coaxial cable? I wasn't
    >sure if the coaxial cable was wired or made differently inside then the
    >audio composite cables were.

    You should use a 75 ohm coaxial cable, that is designed to have a constant
    impedance. Any video cable should do.

    If you use a cable that isn't rated for impedance and isn't constant impedance,
    it will probably work for short lengths, but then again it might not. Since
    video cable is dirt cheap, just use it.
    --scott
    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."
  4. Archived from groups: rec.audio.pro (More info?)

    On Thu, 22 Sep 2005 16:29:35 -0700, Sseadoubleyou wrote:

    > Can you use a 'regular' left or right composite cable to make a coaxial
    > connection or do you have to get an actual coaxial cable? I wasn't sure
    > if the coaxial cable was wired or made differently inside then the audio
    > composite cables were.

    "Coaxial" means the shield wire (or "ground", or "-") wire is in the form
    of a spiral or braided tube which surrounds the hot (or +) wire. It has to
    do with the physical construction of the cable; it doesn't really describe
    a "connection" at all (although it can describe a "connector", which has a
    similar construction to a coaxial cable).

    "Composite" means something made up of various parts, but I have no idea
    what you intended to mean by your use of the word.

    Now, the question I THINK you are asking is "Is there a difference between
    the coax cable sold for digital use & regular old everyday shielded
    cable?" If that's the right question, then the answer is "yes". Digital
    coax (and video coax) is 75 ohm cable. It's actually more similar to the
    coax that carries your cable TV signal into your house that it is to any
    knid of audio cable.

    As I understand it, the "75 ohm" designation means that regardless of
    length (or at least within any "reasonable" length), a 75 ohm output will
    still match to a 75 ohm input. It's not a measurement of the impedance
    or resistance of the cable itself. This wouldn't be important for normal
    analog audio, because the cable lengths are typically shorter, and the
    frequencies are lower. It makes a bigger difference for video or digital,
    where the frequency is much higher.

    Now I'm not an EE, so hopefully if I'm way off base somebody will give us
    the correct scoop.
  5. Archived from groups: rec.audio.pro (More info?)

    Agent 86 wrote:
    > On Thu, 22 Sep 2005 16:29:35 -0700, Sseadoubleyou wrote:
    >
    >>Can you use a 'regular' left or right composite cable to make a coaxial
    >>connection or do you have to get an actual coaxial cable? I wasn't sure
    >>if the coaxial cable was wired or made differently inside then the audio
    >>composite cables were.
    >
    > "Composite" means something made up of various parts, but I have no idea
    > what you intended to mean by your use of the word.

    I suspect that he means a cable that is intended to carry a composite
    video signal. But then he goes on to call it audio, so perhaps not.

    To the original poster: Video, whether composite or component, is
    carried on 75 ohm cable. Digital audio (S/PDIF, Dolby Digital, or DTS)
    is also carried on 75 ohm cable. So the coax that is used for any of
    these purposes is interchangeable. You can buy a video cable and use it
    for digital audio. You can buy a digital audio cable and use it for video.

    However, analog audio does NOT require 75 ohm wire. So most typical
    left/right stereo audio cables are NOT suitable for carrying video or
    digital audio.
  6. Archived from groups: rec.audio.pro (More info?)

    "Jim Gilliland" wrote ...
    > However, analog audio does NOT require 75 ohm wire.
    > So most typical left/right stereo audio cables are NOT
    > suitable for carrying video or digital audio.

    I guess it depends on your definition of "suitable"?

    For short distances (2-3 feet), barbed-wire is "suitable" in the
    sense that it will work. Certainly such short distances do not
    know or care whether you have an impedance-matched transmission
    line or simply something that will get the ones and zeroes to the
    other end intact.
  7. Archived from groups: rec.audio.pro (More info?)

    Sseadoubleyou wrote:

    > Can you use a 'regular' left or right composite cable to make a coaxial
    > connection or do you have to get an actual coaxial cable? I wasn't
    > sure if the coaxial cable was wired or made differently inside then the
    > audio composite cables were.

    It would help answer you if you explained what you mean by a 'composite
    cable'. It is not a term in standard use.

    Coaxial simply means what it says. The signal and shield conductors share
    the same axis. Simply a cable where the signal conductor runs inside a
    circular shield made from braided or lapped wire.

    Many types of wire use this construction. The term 'coaxial' is in practice
    normally specifically used to denote suitability for radio frequency use (
    including video and digital audio ).

    Typical audio 'single screened' cable is not normally called coaxial
    despite having that style of construction. Audio cable like this isn't
    intended for radio frequewncy use either.

    No cable is called composite, although coaxial cables are regularly used to
    make 'composite video' connections ! Composite video refers to the type of
    signal - not the cable.

    Graham
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