digital coax vs optical

Discussion in 'Home Theater Projects' started by Bryan_K, Dec 2, 2003.

  1. Bryan_K

    Bryan_K Stunt Coordinator

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    Could someone please explain the benefits of using optical vs digital coax. The only difference i know of is that optical costs twice as much.

    I have a DD/DTS receiver & have been using a digital coax connection for years. It sounds wonderful to me. While setting up a Friends HT, i recommended the coax cable because of price benefit. Is optical worth the 100% price difference?
     
  2. Chu Gai

    Chu Gai Lead Actor

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    If you run short of one input then optical might just save your ass. Also, every now and then, someone gets a nasty electrical interference problem and running optical provides a quick and ready solution to that. Other than that it's really a question or matter of what your equipment supports and your particular preferences. Overpriced examples of both types of technologies abound.
     
  3. ChrisLazarko

    ChrisLazarko Supporting Actor

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    Usually optical is better for a long run, and digital coax is good for shorter runs, something under 10-15 feet or so. I personally prefer digital coax, but I don't hear a difference between the two, I just find the digital coax to save a litlte money and to do the same job optical does.
     
  4. John S

    John S Producer

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    I like the way the little red light comes out of the optical cable.... lol

    I really have never heard any audible difference whatsoever.
     
  5. ChrisLazarko

    ChrisLazarko Supporting Actor

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    Yeah the red light is really cool, then you see it on the other end. Everyone who saw that thought it was the neatest thing. So one thing about the optical for the + side... bright red light!
     
  6. John Garcia

    John Garcia Executive Producer

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    I don't know where you are shopping, or what stores you have, but optical cables should be very easy to find for much less than a decent coax. Locally, cheap 1M optical can be found for $9.

    Good coax digital actually sounds better to me. I went from Monster coax to Audioquest VSD-2s and there was a significant improvement in detail. I prefer RCA connection to optical as well.
     
  7. JamesCB

    JamesCB Second Unit

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  8. Krelkor

    Krelkor Auditioning

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    i dont see WHY there would be a difference other than if for some reason the output circuits were drastically different...
    both use 1s and 0s....
     
  9. John Garcia

    John Garcia Executive Producer

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  10. Michael Reuben

    Michael Reuben Studio Mogul

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  11. LiorM

    LiorM Agent

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    common-sense ...
    By using the coax cable you are transferring the "bits" as is ( electricity through a copper string )
    Transferring the data through the optical cable will require some conversion process which can couse loss of data and more error the your decoder should handle.
    Unless you need to cary the data for a long distance
    ( then the optical way is preferable ) use the coax cable.
     
  12. Neil Joseph

    Neil Joseph Lead Actor

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  13. Ted Lee

    Ted Lee Lead Actor

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    [​IMG]

    [​IMG]
     
  14. Chu Gai

    Chu Gai Lead Actor

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    Sheesh, when did $40 become cheap?! Let me give you another spin on what you observed/heard John. First I'll make the assumption that what you heard would've been verifiable in a controlled environment and the further assumption that neither cable was defective in any way.

    In situations where it can be established that a change in cable results in an audible difference, invariably one finds that the capacitances of the two cables are different. One might interpret this as proof positive that cables make a difference. This is though an erroneous and gratuitous conclusion but one that the cable mongers are well aware of. Rather, when observed, this is due to a problem in either the source, destination or both devices. If your player has poor ability to drive a current, either through improper design or a subtle breakdown if you will, then this manifests itself as problems in the rise-time of the output stream. This can and does affect the performance of a good DAC. But let's say that the DAC in your receiver isn't quite so good because the overall design isn't as electrically isolated as it should be. Then the DAC takes this 'iffy' clock output and turns it into audible jitter that's very dependent upon the musical source. Noise then increases among other things.

    Now I'll bet that if you were able to find out the capacitances of the two cables, that you'd find your Audioquest had a lower one.
     
  15. Chu Gai

    Chu Gai Lead Actor

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    Lior...
     
  16. Mike Veroukis

    Mike Veroukis Second Unit

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    Well, the optical cable simply can not interfere with other electromagnetic transmissions. It will not bother any other wires or cables with any electromagnetic energy. Of course, this is negligible, but for the sake of argument, it's one benefit. The other is that it dramatically reduces the chance of a ground loop hum between two components if they are connected via optical cable. That's probably the most advantageous feature. The down side with anything optical is that dust can cause problems, but nothing a can of compress air can't fix! [​IMG] Oh yeah, not sure how true this is, but I heard that if an optical cable is forced to bend at a really sharp angel it can somehow interfere with the transmission - but that too is easily solved by not bending the cable too much!

    - Mike
     
  17. Ted Lee

    Ted Lee Lead Actor

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    hmm...have some heavy hitters here...john, chu, neil, michael....so i'll ask the question...even though that poor horse can't take much more.

    i'm interested in the "it's 0's or 1's" argument. it sounds logical to me. either it works...or it doesn't. it doesn't matter what cable is used to transmit the data - the end result is binary data being sent to the converter.

    opinions on that???
     
  18. Chu Gai

    Chu Gai Lead Actor

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    basically yes Ted. You might recall a thread I posted over in Tweaks some time back that spoke of the ability to use a coat hanger as a digital interconnect. I've even heard of something even more bizarre and that's having a digital signal transmitted through a person.
    Jitter, which can and does vary in cables, is too small of a variable to have any importance for the lengths that we're likely to use. This conclusion was stated by the late Julian Dunn.
    The issue which I brought up regarding capacitance primarily has to do with some sources having problems with cable capacitances that are 'high' although that's a pretty relative word. A source that is designed robustly would not have an issue with cable capacitance. It would send the signal through without any noticeable effect on the rise time. Consider the following graph that I dug up.
    [​IMG]
    The rise time of the top trace is nice and sharp while the bottom one has a longer rise time. The bottom one is analgous to what would happen if your source had an issue with cable capacitance. If you look carefully at some of the offerings from say AudioQuest, you'll find a correlation between price and cable capacitance. Lower the capacitance, higher the price.
    I truly don't know what Mr. Garcia's particular situation is nor am I casting dispersions on his equipment. I'm simply stating what it is that I know has happened. The analogy that comes to mind is you buy a car and find it only runs well on Exxon gasoline. Now did you buy a discriminating car or is your car poorly designed? I vote for the latter.
     
  19. Shane Martin

    Shane Martin Producer

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  20. Chu Gai

    Chu Gai Lead Actor

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    oil does not equal gas.
     

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