What are the difference between Coaxial and Optical inputs?

Discussion in 'Archived Threads 2001-2004' started by BrianFS, Apr 9, 2002.

  1. BrianFS

    BrianFS Auditioning

    Joined:
    Apr 7, 2002
    Messages:
    9
    Likes Received:
    0
    Do optical inputs give you higher quality sound? I heard optical is warm and coaxial is sharp, but I don't know what that means to my ears. Can someone explain the differences in layman's terms? :b
     
  2. Selden Ball

    Selden Ball Second Unit

    Joined:
    Mar 1, 2001
    Messages:
    412
    Likes Received:
    1
    Real Name:
    Selden
    Brian,

    It really depends on your equipment. Whatever difference there is to hear is quite subtle. Most people can't hear any difference at all.

    There are lots of rationalizations why the two *might* sound different, of course, and far too many arguments about them.

    If you have the opportunity -- a player with both kinds of outputs and a receiver with both kinds of inputs -- you should listen for yourself and make up your own mind.
     
  3. Bill Kane

    Bill Kane Screenwriter

    Joined:
    Feb 5, 2001
    Messages:
    1,359
    Likes Received:
    0
    Welcome to the forum, Brian.

    If you have the opportunity, pls get familiar the thread above, "A Primer for HT Newcomers" to asnwer many of the things you will be wondering about.

    bill
     
  4. Ian Montgomerie

    Ian Montgomerie Stunt Coordinator

    Joined:
    Feb 2, 2002
    Messages:
    112
    Likes Received:
    0
    The main difference between optical and coaxial digital cables is that they look different, and they hook into different connectors on the back of your equipment.

    In other words, because the signal is carrying digital information, there will be absolutely no difference between the cables unless something really bad happens and you get errors (for example, if you bought a bum cable). If you had extreme electrical interference, for example (maybe you are running a radio station out of your house...), you might want an optical cable as they are not subject to that interference. Coaxial cables, on the other hand, are cheaper and more resistant to sharp bends in the cable.

    If someone tells you there is some subtle difference between digital interconnects, like one sounds "warmer", rest assured that they have no clue how digital signals work. If you have a bum cable it will not be hard to tell, play some DTS or Dolby Digital through it and you will get audio dropouts (short periods of silence). Or playing a CD through it, you would likely hear popping and clicking noises.

    If you buy a more expensive digital cable, it will probably come with a better grip so the small chance of it slipping loose becomes smaller. If the cable ever slips loose, you will notice.

    (If you want credentials for this - since inevitably when this subject comes up, a bunch of "audiophiles" will post alleged reasons why one digital cable would sound better than another - I'm an engineer working for a leading manufacturer of DVD player microchips, and I have a pretty good idea of how this technology works under the hood, and exactly what digital data transmission errors sound like in the various DVD audio formats).
     
  5. Marc Rochkind

    Marc Rochkind Second Unit

    Joined:
    Aug 26, 2000
    Messages:
    381
    Likes Received:
    0
    Good answer, Ian. It's interesting that people often ascribe analog properties to digital processes.

    I've been using personal computers since around 1982 (and non-personal ones before that), and I have used the following approach to buying digital cables for my computer, with very successful results:

    "Get the cheapest."

    And, for sure, the stuff I do on my computer is around 10,000 times more critical than anything I've done with my home theater.
     
  6. Neil Joseph

    Neil Joseph Lead Actor

    Joined:
    Jan 16, 1998
    Messages:
    8,332
    Likes Received:
    1
    Real Name:
    Neil Joseph
    Optical digital Connection/Coax digital connection

    The digital connection between a DVD player and a receiver is needed in order to transfer the audio from the DVD player to the receiver/processor. The audio is sent out from the DVD player as a digital bitstream of 1's and 0's as apposed to an analog format. There are basically two different types of cables that can be used to transfer this data, a digital optical cable and a digital coaxial cable. Most of the newer generation of DVD players have both capabilities but some older models only had a coaxial connection. Let us examine some of the characteristics of each type of connection...

    Digital Optical

    This cable is actually a fiber optic cable. It snaps into position on the optical output of the DVD player while the other end connects to the optical input of the receiver/processor. The DVD player transfers the digital audio bitstream of 1's and 0's as light pulses down the fiber optic cable where the receiver then decodes the information and converts it to an analog format that can be played to the speakers. The advantages of the optical cable are there is absolutely no RF noise or interference (typical of cheaper coaxial cables). Also, the light pulses can be transferred over long distances with minimal loss. Typically though, most commercial cables are either 3 or 6ft in length and longer runs need to be custom made. The disadvantages include a typically higher cost than the average coaxial cable, a connection that is not as robust as the more sturdy coaxial connection, and the possibility of data loss if the cable is bent at a sharp angle.

    -----------------------------------------------------------------------------------------------------------

    Digital Coaxial

    This cable is a typical shielded coaxial cable with "RCA" ends. It is plugged into the DVD player's digital coaxial output while the other end connects to the receiver's digital coaxial input. As with the optical cable, the DVD player transfers the digital audio bitstream of 1's and 0's but as electrical pulses down the cable where the receiver then decodes the information and converts it to an analog format that can be played to the speakers. The advantages of the coaxial cable are it's sturdy connectors (the cable is difficult to damage). Also, the cables are generally cheaper than the average optical cable and are more readily available. The disadvantages include the possibility of RF noise or interference, although the shielding provided on today's coaxial cables practically negates this disadvantage.

    -----------------------------------------------------------------------------------------------------------

    So which is better?

    Both types of cables more than meet the simple specifications of this simple task of transferring the digital audio bitstream. Both work equally well although there have been those who advocated one over the other due to audio differences. Whether this is a placebo effect or not is debatable. In the end though, they are transferring a digital medium, which is different from transferring an analog medium that is indeed cable dependant. My personal deciding factor is price and having the more robust connection, important especially if the cable will be disconnected and reconnected several times.
     
  7. Artur Meinild

    Artur Meinild Screenwriter

    Joined:
    Aug 10, 2000
    Messages:
    1,294
    Likes Received:
    0
    This is what I heard (and think sounds reasonable):
    Since the signal from the DVD players audio processer is an electrical signal, and the amp's surround processer also takes an electrical signal, a coaxial cable is the most "direct" connection, since you stay in the electrical domain.
    For optical cables, the DVD player has to convert the electric signal to light, and the amp has to convert the signal back to electric, and of course errors can occur during this conversion.
    Therefore, coaxial cables are best on short distances. However, I'm not in a second doubting optical cables strength when it comes to greater distances.
    Furthermore, I don't think the difference is audible! [​IMG]
     
  8. Sebastien David

    Sebastien David Second Unit

    Joined:
    Dec 4, 2001
    Messages:
    291
    Likes Received:
    0
    i heard that when you plug an optical cable its your receiver that would decode the signal(dts or pro logik)
    but whit the coax cable your signal would be transfered decoded.So you choose your cable in function
    *if u have a super receiver and a so-so dvd your better
    to plug in whit optical .
    *but if u have a so-so receiver and a super dvd so plug in coax
    is this thruth!!
    [​IMG]
     
  9. Bob McElfresh

    Bob McElfresh Producer

    Joined:
    May 22, 1999
    Messages:
    5,182
    Likes Received:
    0
     
  10. Sebastien David

    Sebastien David Second Unit

    Joined:
    Dec 4, 2001
    Messages:
    291
    Likes Received:
    0
     
  11. Bob McElfresh

    Bob McElfresh Producer

    Joined:
    May 22, 1999
    Messages:
    5,182
    Likes Received:
    0
     

Share This Page