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HELP NEEDED - building a "splitter box"


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  • HELP NEEDED - building a "splitter box"

    I'm making a 'splitter box' for a micophone. Fairly simple idea, it has a XLR input for the mic and 2 1/4" mono jack outputs. One goes to the PA for live sound and the other goes to the mixing desk for recording.


    I've put it together. :smileythumbsupsmall:


    But I have no idea how to wire it up :smileysurprised:.png" />


    Any help would be much appreciated.


    splitbox1.JPG splitbox2.JPG

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  • #2

    You cannot do this properly just with hookup wires among the jacks.

    The microphone signal coming in is balanced, but the 1/4" outputs are unbalanced.

    If you want to keep this all passive (no external power source), you need a "balun" transformer which converts the balanced signal to unbalanced. The output of the transformer can be passively split to two destinations.

    Another solution is to make this an active box: build a standard, off-the-shelf balanced input circuit around an op-amp, and split its output into two. If you have spare op-amps devices, you can buffer the outputs individually. And while you're at it, put in some gain so that the unbalanced lines are at line leve, rather than microphone level.

    You really don't want to be unbalancing a mic signal and then sending it down lengths of unbalanced cable.

    You could do this wrong and just pick up half of the balanced signal. You will get all the noise that the balanced system cancels out. This is a complete nonstarter at the voltage levels coming from a low impedance pro microphone, and the amounts of gain they are subject to.






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