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Plugging an already balanced signal (1/4") into a di box

Discussion in 'Live Sound [BG]' started by ryansalmond, Nov 4, 2013.

  1. ryansalmond


    Nov 21, 2007
    Did this a few nights ago at a gig and had tonnes of feedback issues, still trying to figure out what the problem was, could it have been this?
  2. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009
    "feedback"? what exactly do you mean by that?

    anyway, the DI box was unnecessary, all you needed was a 1/4" TRS to XLR male adapter.
  3. Yeah, a big 'what the _' were you up to exactly?

    1/4" TRS outputs from instruments are usually stereo, not balanced mono.
  4. Hi.

    IMO no, You either get noise or impedance mismatch related problems or no sound at all.

    Why feed a balanced signal to an unbalanced device anyway?

  5. ryansalmond


    Nov 21, 2007
    Because the soundman couldn't take 1/4" inputs and all he had to 'adapt' them to xlr were DI boxes.
    I think I'm going to buy adapters yeah.
  6. ryansalmond


    Nov 21, 2007
    Though then again, the cables used to go from the device (a stereo mixer/preamp of mine) to the DI's were probably unbalanced.
  7. Hi.

    OK, that makes sense.

    If Your cables were TS = mono cables, those connections were unbalanced.

    The feedback issues were then probably caused by incorrect gain structure along the signal path.

  8. ryansalmond


    Nov 21, 2007
    Ok so it wasn't the balanced thing, good to know.

    Could you elaborate on incorrect gain structure?
  9. Biggbass


    Dec 14, 2011
    Planet Earth
    If a sound guy cannot figure out how to get a Bass> DI > board correctly without F-ing it up then you are working with a sound guy that doesn't know what he is doing.
  10. Gain is what is meant by the stages of amplifying the bass pickup signal millivolts into eventually tens of speaker volts.

    In your case the preamp output may have been already powerful enough to drive a power amp but plugged into an instrument level DI would have severely overloaded it.

    Even if those outputs were balanced it would have been no problem using a mono lead into a line level set DI. Most DI boxes can do either by padding down line level.
  11. Dave W

    Dave W

    Mar 1, 2007
    White Plains
    Based on your other post there was no balanced thing.
  12. Hi.

    Pays to read the thread ;).
    It wasn't "Bass> DI > board" type of situation.

    Yes, and when there's many stages of unknown qualities on the chain, problems do arise.
    Nothing that a little knob twisting and perhaps a PAD won't cure though.

    Using DI boxes for such tasks as the OP is the "standard" though, most sound techs (including a hobbyist like me ATM) know better than to directly connect an unknown balanced 1/4" signal straight to their FOH board.
    Always better to have a DI in between, preferably with galvanic isolation.

  13. ryansalmond


    Nov 21, 2007
    Thank you Downunder and T bird
  14. You're welcome.
    You might want to snag the Countryman 85 DI in the classifieds. Most any soundman knows what it is and won't give you any grief to use it.
  15. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    JOOC, what was the device?

  16. TimmyP


    Nov 4, 2003
    Indianapolis, IN
    It had nothing to do with the problem, whether the cable used was a TS or a TRS.

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