SPDIF: COAX vs. TOSLINK

Discussion in 'Beginners, General Questions' started by Seth=L, Jul 23, 2006.

  1. Seth=L

    Seth=L Screenwriter

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    I have heard from many audiophiles that coax is superior by far to toslink. Why is it that companies like toslink tell consumers that it is better?

    Is it true that toslink (EIAJ Optical) has a brandwidth of only 6Mhz while coax has the potential of 500Mhz. It would seem this would make a world of difference.

    Seth=L
     
  2. Nick:G

    Nick:G Stunt Coordinator

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    This is a debate that will never end. Audiophiles consider coaxial connections to superior for digital because of the absence of "jitter" that can be caused by optical cables of poor quality and/or a loose connection between the cable and the component.

    In most applications, you'll be hard pressed to discern any audible difference between the two. In some cases, certain components will sound better over coaxial connections than optical ones, or vice-versa.

    In whole, I've always preferred coaxial connections because RCAs simply seat better and don't fall out of the plugs near as easily.

    As far as bandwidth is concerned between the two digital connection types, it is really a non-issue. These connections are used mostly to pass bitstreams and there's plenty of bandwidth with either type to get the job done. Toshiba will always say Toslink is better because they hold the patent on the technology.
     
  3. Jeff Gatie

    Jeff Gatie Lead Actor

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    No difference. Jitter only matters in PCM streams, DD and DTS are self timing and 6 Mhz is more than enough bandwidth. The only difference you could discern is if the optical->electrical conversion is not up to par with the coax, but that is a fault of the component, not the cable. Besides, optical is a pretty mature technology and the situation of having a lousy conversion would be very rare.
     
  4. Lew Crippen

    Lew Crippen Executive Producer

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    It really makes no difference, as mentioned. The bandwidth issue is a non-issue, as there is plenty (as Jeff writes) to pass the 0s & 1s. There may be a reason to prefer one over the other if you have a long cable run, as many DVD player (and satellite receiver) lasers need a signal boost along the way.
     
  5. Joe D

    Joe D Supporting Actor

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    I prefer COAX:

    1. COAX tend to fit a bit better

    2. 75 OHM COAX cables can also be used for video, subwoofers, etc.

    3. Cheaper / foot
     
  6. Yee-Ming

    Yee-Ming Producer

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    I just got a laptop, and was introduced (for the first time, ignorant me!) to the fact that optical cable connectors came in two flavours, the square Toslink, and the mini jack (that looks just like the jack on your earphones). If I have an optical cable that has Toslinks connectors at both ends, would getting an adaptor -- which looks like a hollow stereo plug, and accepts the Toslink connector -- to use on the Toslink, so that it fits into the jack output, be acceptable, or is it better to just pony up and buy a new cable that specifically has Toslink on one end and mini-jack at the other?
     
  7. John Garcia

    John Garcia Executive Producer

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    What Joe D said. Also, much more positive connection so it is much less likely to fall out. I've had it happen with cheap optical cables.

    Check around, MANY optical cables come with mini adapters already in the box, or just get an adapter:

    [​IMG]

    $1.95 ea Link
     
  8. Tony Loewen

    Tony Loewen Stunt Coordinator

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    As a user of an HTPC set up, I can attest to the fact that when using optical connections, you eliminate any ground loops or hum. It is electically isolated, so you don't pass on any electrical noise. My 2cents
     
  9. chuckg

    chuckg Supporting Actor

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    Hurray!

    I'm glad Tony mentioned ground loops. I would be quite happy if all my connections were optical, including those for video. And even happier if all the audio setups for sound reinforcement and so on were optical. Ground loops are the devil incarnate.

    For goodness sakes, internet traffic travels overs thousands of miles of glass fiber at speeds far above those necessary for audio and video. I've never had any trouble with the Toslink square connectors, and we've got them in some equipment at work that have been in constant use for twelve years with no failure.

    So, when do I get glass from the providers all the way to my equipment?
     
  10. Seth=L

    Seth=L Screenwriter

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    Digital sources have to change electric to optical and then a receiving processor of sorts must convert it back to electric.

    Seth=L
     
  11. chuckg

    chuckg Supporting Actor

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    The conversion of an electrical digital signal into an optical digital signal is the simplest possible thing.

    The exact same on/off electrical signal turns the transmitter's laser diode on and off, resulting in a light that turns on and off just as rapidly and perfectly as the electrical signal can do.

    Converting the flickering light back into electricity is done with a photodiode or phototransistor, each of which can produce an electrical signal exactly identical to the original electrical signal from the transmitter. there is no processing of the signal; the information content does not change.

    The only real difference is whether we are using electrons or photons to carry the information.

    The great advantage of optical connection, as has been pointed out, is that the two systems are electrically isolated, and there can be no chance of a ground loop. The choice of electrical or optical transmission is otherwise purely arbitrary.

    The digital signal, whether electrical or optical, is relatively immmune to problems from interference, and small variations in intensity.
     

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