Digital impedence

Discussion in 'Archived Threads 2001-2004' started by John DeSantis, Dec 20, 2001.

  1. John DeSantis

    John DeSantis Stunt Coordinator

    Joined:
    Nov 18, 1999
    Messages:
    202
    Likes Received:
    0
    Are Digital audio cables supposed to be 110 OHM or 75 ? I know alot of people will say it doesn't matter etc. I just wanted to know what it's supposed to be.
     
  2. Jagan Seshadri

    Jagan Seshadri Supporting Actor

    Joined:
    Nov 5, 2001
    Messages:
    528
    Likes Received:
    0
    The characteristic impedance depends on the style of cable. For coaxial digital cable (which is literally two coaxial or concentric conductors) it is 75 ohms. For a twisted pair cable (literally two conductors twisted around each other) then the impedance is 110 ohms. These values are due to the way the cable geometries affect the electromagnetic field calculations.

    -JNS
     
  3. Bob McElfresh

    Bob McElfresh Producer

    Joined:
    May 22, 1999
    Messages:
    5,182
    Likes Received:
    0
    John - a subtile point - most of the arguments cover inexpensive/modest/expensive costs on the cable. But everyone agrees that the coaxial digital cables should be made with 75 ohm coax. (This is what the Sony Phillips Digital Interface specification call for - 75 ohm coaxial).
     
  4. John DeSantis

    John DeSantis Stunt Coordinator

    Joined:
    Nov 18, 1999
    Messages:
    202
    Likes Received:
    0
    OK, thanks. That's what I wanted to know. 75 OHM it is !!!!!!
     

Share This Page