Creative Communities of the World Forums

The peer to peer support community for media production professionals.

Activity Forums AJA Video Systems Possible for LA to output 4 channels of analog audio with ch 3/4 mirroring ch 1/2?

  • Possible for LA to output 4 channels of analog audio with ch 3/4 mirroring ch 1/2?

    Posted by Tom Matthies on May 29, 2005 at 10:59 pm

    I have an IO LA for outputting from FCP. Right now, I have channel 1 & 2 from the LA going to a mixer. I’d like to use channel 3 & 4 from the LA and go to the input of a Tektronix audio phase/level meter. What I’d like to do is send FCP’s left (Ch-1) signal out of channel 1 and 3 of the LA and FCP’s right (Ch-2) out from channel 2 and 4 of the LA. Both the mixer and the Tek scope have XLR inputs and can connect directly to the LA.
    All of the balanced outputs from the mixer are being used, so that rules out connecting it to the mixer without first going thru an audio DA.
    Is it possible to have the LA’s channel 3/4 outputs mirror the channel 1/2 outputs?
    Thanks,
    Tom

    Bob Zelin replied 19 years ago 3 Members · 4 Replies
  • 4 Replies
  • Bob Zelin

    May 30, 2005 at 12:34 am

    there is no reason why you cannot “mult” or “Y” the output of the I/O to feed the Tek scope input. There will be no loading effect that will reduce or degrade the signal. Just use channel 1 and 2 with an XLR Y, and you will have no issues.

    Bob Zelin

  • Christopher Tay

    May 30, 2005 at 1:33 pm

    What you can do is to duplicate your audio track 1,2 to track 3,4 in your timeline and then set the track’s output to the relevant XLR output on the LA and you’re set.

    -chrispy

  • Tom Matthies

    May 31, 2005 at 4:23 am

    “there is no reason why you cannot “mult” or “Y” the output of the I/O to feed the Tek scope input.”

    >Hmmm… Since I want to use this for an accurate level indicator, putting a “Y” XLR cable in the mix won’t load the output of the LA enough to change the levels? It would then send the LA output to the Tek scope and to a mixer.
    No significient loading or phase problems, eh?
    Well, it’s an easy solution to the problem, no doubt. And easy to do as well. I guess sometimes, the most practical isn’t the most obvious. I’ve just spent too damn many years DA-ing everything. Splitting the signal…well, that’s just not proper…is it?

    What I really should do is to put the Tek scope on the output of the mixer for an accurate level on what’s going to my BetaSp deck. It’s got a +4db XLR output so the same principal of splitting should apply, I’d guess.
    ____________

    “What you can do is to duplicate your audio track 1,2 to track 3,4 in your timeline and then set the track’s output to the relevant XLR output on the LA and you’re set.”

    -I have done this, but in this case, there are 8 tracks to the audio portion. I can duplicate them and assign them to outputs 3/4, but It’s a cumbersome solution at best. I have an IO that goes to a Digibeta as well and it seems to send a dual stereo signal to the deck thru the SDI output. I was hoping there was a similar solution for the analog LA as well.

    Thanks,
    Tom

  • Bob Zelin

    May 31, 2005 at 10:25 pm

    Of course the correct answer, as you stated, is to use audio DA’s, but NO ONE (certainly not on this forum) would PAY for audio DA’s. I can assure you, that if you use the Y cord (or multing, as has been used in studios for years), and start with the Tek Scope – set your +4dBu level, and while observing the scope, plug in the AJA I/O LA inputs, you will see NO LOSS OF LEVEL on the Tek scope (gee, this is VERY REASON you bought that scope in the first place).

    The only time you will see load errors are from items like Sony VTR’s that have 600 ohm (low impediance) terminations. This of course, is resolved by turning off that damn 600 ohm termination switch.

    But once again- you are “theoretically” correct – everyone here should be using audio DA’s.

    Bob Zelin

We use anonymous cookies to give you the best experience we can.
Our Privacy policy | GDPR Policy