7 Replies Latest reply: Jul 12, 2006 2:10 AM by iSchwartz
Timothy B Hewitt Level 4 (1,540 points)
Do I need a specific cable for SPDIF, or will any RCA work?

G5 1.8 DP | 3 Gb RAM | iBook 1 GHz | 640 Mb RAM, Mac OS X (10.4.5), LP 7.2 | RME FireFace | UAD-1 (3) | Avalon stuff | Neumann U87
  • kcstudio Level 4 (1,650 points)
    Timothy as long it is reasonable quality wise and the length does not exceed approximate 1meter it should work. Beware of jitter though if the cable gets to long!
  • muzak Level 3 (650 points)
    To get stereo SPDIF you need coax cable, RCA is mono.
  • tele_player Level 5 (5,380 points)
    That is not correct. S/PDIF is stereo, and typically uses RCA (aka phono) plugs.

    Have you ever used these things?
  • Gary Maguire Level 1 (130 points)
    you need a 75 Ohm cable for s/pdiff, Lengths can be up to about 5 meters although you will get away with longer. In my experience a bog standard phono lead will do but it does depend on the bit of kit being used and can be prone to jitter. S/pdiff is a dual mono signal so don't necessarily have to be a stereo signal coming through it.
  • tele_player Level 5 (5,380 points)
    Yes, I should have written 'S/PDIF carries two channels of digital audio'.
  • Timothy B Hewitt Level 4 (1,540 points)
    Thanks for the input guys!
  • iSchwartz Level 5 (4,315 points)
    OT, but related...

    My partner and I both have Mackie D8B's and MOTU 2408's. When I record out of the board and into Logic I always use lightpipe, but he's been using SPDIF. Now, I thought that his mixes always sounded a little weird in mono. So in troubleshooting the situation I discovered that if we took a CD track, played it out of Logic, through the board and back into Logic via SPDIF that there were problems... When I put the new recording out-of-phase with the original, it would never phase cancel completely. For example, the right side could be heard slightly while the left side would completely cancel. If I moved the re-recorded track by 1 sample, then the opposite would occur: the left side was heard slightly while the right side cancelled.

    Of course, getting even this close to complete phase cancellation means that my recording delay had to be set to somewhere near the right value, and it was:  -25 samples. Only thing is that you couldn't tell exactly in this scenario. So then....

    Then I tried the same experiment re-recording the track through the board using lightpipe. Bingo, I was able to achieve perfect phase cancellation between original and re-recorded tracks.

    So this lil' experiment showed me that, at least as far as a SPDIF transfer between his Mackie D8B and Logic (via a 2408 interface) that there was some kind of "interleaving" problem going on.

    So since we're talking SPDIF, any ideas as to why this would occur?