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Digital Audio: Co-ax or Optical ?

Discussion in 'AV Receivers & Amplifiers' started by Mr Sparkle, Nov 3, 2003.

  1. Mr Sparkle

    Mr Sparkle
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    Hi,
    I'm trying to find out what is the 'best way' to connect the digital audio o/p of my DVD player to my AV amp ?

    Should I go with a digital co-ax cable or a digital optical cable ? (DVD player and A/V amp support both)

    Are there an advantages/disadvantages for the above ?

    Many thanks in advance.

    Mr Sparkle
     
  2. Nobber22

    Nobber22
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  3. Mr Sparkle

    Mr Sparkle
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    Thanks!

    Searched a bit more thoroughly and this question is asked pretty regularly!

    Mr Sparkle
     
  4. fred123go

    fred123go
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    haha yup it has and ages ago on this forum there was a heated debate about it lasted tens of pages,
    but yeah the basics:
    both are the same basically, co-axial better in theory, optical better over longer distances.
    No matter which one you use they will produce the same sound IMO
    Fred
    p.s. best stick with co-axial
     
  5. StooMonster

    StooMonster
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    Is it not true that optical is 48kHz whereas coax is 96kHz?

    StooMonster
     
  6. fred123go

    fred123go
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    i think you may be wrong here, i have not seen anything like this on any of the other threads, where did you find this information?
    Fred
    p.s. if they are i think i may be changing soon....
     
  7. michaelab

    michaelab
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    It's true AFAIK that optical (TOSLink) is limited to a 48kHz maximum sample frequency. Coax is limited to about 96kHz (which is why, for example, my Chord DAC64 requires two coax inputs to support 192kHz).

    Since 99% of CDs and DVDs are still either 44.1kHz or 48kHz then the sample frequency limitation should be a reason to not use optical.

    IME though, you'll get better results with coax than optical.

    Michael.
     
  8. fred123go

    fred123go
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    oh well looks like i will be buying a new coaxial cable
    Fred
     
  9. buns

    buns
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    optical is NOT limited to that if you get the right one..... just happens that consumer audio uses limited cables
     
  10. michaelab

    michaelab
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    buns - I'm talking about TOSlink, not AT&T or ST glass optical which only ultra high-end (and then usually only stereo) equipment has.

    The TOSlink you're likely to find in any consumer product (and therefore, what's relevant to this thread) is limited to 48kHz.

    Michael.
     
  11. fred123go

    fred123go
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    Hey there,
    I don't get this 48khz and 96 khz stuff, is it the speed at which signals are sent?if so why does my can den hul optocoupler optical cable claim to send 250 megabites per second
    cheers
    Fred
     
  12. buns

    buns
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    it isnt the speed...... speed of light is constant no matter what cable you care to use :p

    It is the frequency of the signal..... seeing as im not sure on the definition of bite (which surely isnt the spelling) I cant say whether VDH are true or not.

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  13. michaelab

    michaelab
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    It's the sampling rate which is related to the speed of data transfer. Each digital sample is sent as part of a 32bit word in the SPDIF protocol (which is used for TOSLink, coaxial and AES/EBU) regardless of the bit resolution of the source (ie whether it's 16bit CD or 24bit upsampled) so you're talking 44100 samples of 32 bits per second which is 1,411,200 bits or 1.4Mbits per second.

    250Mbits per second (they surely weren't claiming 250Mbytes per second!) still sounds incredibly high - that would imply it supported a maximum sample rate of 7.8megahertz which I simply do not believe (what's more there's absolutely nothing in the consumer world that's anywhere close, even digital video, to requiring such a high sample rate). It is totally impossible for an optical cable (or a coaxial cable for that matter) to handle such a high bandwidth.

    What they might have meant was 2.5Mbits per second which would imply a max sample frequency of about 78kHz which sounds possible - but you still couldn't use it to transmit 96kHz signals which is probably what fred123go is after.

    Michael.
     
  14. fred123go

    fred123go
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    cheers michael,
    i will quote exactly as it says on the back:
    "regarding the cable itself we guarantee a minumum transfer capacity of 250 Megabit/second."
    i don't have a clue what that means but i suppose it is good, so you were saying that optical just can't transmit 96 khz, even with this rate?
    cheers
    Fred
     
  15. michaelab

    michaelab
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    I simply don't believe that 250megabit per second number (or I don't know on what basis they've calculated it). I doubt very much that it is 96kHz capable but you're welcome to try it :) Why not send an e-mail to VDH asking them?

    Michael.
     
  16. buns

    buns
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    It isnt that optical cant do it, rather it is the particular standard of optical cant do it..... if you get that wrong you will be mighty confused when the future arrives!

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  17. fred123go

    fred123go
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    i have sent an email but that is definately what it said on the back
    cheers for your help
    Fred
     
  18. lowrider

    lowrider
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    Those megabits are probably word size, 16, 24 or whatever times the frequency, so it still doesn´t mean it can pass at 96 khz... :rolleyes:
     
  19. Mr Sparkle

    Mr Sparkle
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    Many thanks for all the inputs....I've now got a new digital coax audio cable which is going on the DVD/Amp tonight.

    Thanks,

    Mr Sparkle
     

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