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XLR to RCA adapter

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  • XLR to RCA adapter

    I have found a number of forum posts in various forums that say pin 3 line should be cut when going from an XLR out to RCA in. Less stress on the op amp I believe (might be something else). I can not find an XLR -> RCA adapter or cable that allows you to open up the XLR connector to make the alteration.

    Any suggestions? It will be connected to the Main XLR outs of a Marantz AV7705 prepro. (I know it has RCA outs also, long story)

    Click image for larger version

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  • #2
    The "theory" is to avoid ground loops which CAN be an issue with "PRO AUDIO" to RCA connections. Sometimes lifting pin three helps, sometimes it hurts. Bitter experience talking. I just hope your AC outlets are correctly wired as to polarity or you'll have a 60Hz buzz that you'll go INSANE tracking down, or I nearly did! Watch keeping your balanced to unbalanced cables well separated too. I had to build a jig to keep them apart to avoid "coupling" noises. Best of luck!


    • #3
      I would not connect pin 3 to ground like that, either. I can't see that it helps anything, and it will pointlessly short the - output. But I have no experience (good or bad) trying to do what you're doing.

      One of the right ways to do that is through a transformer. Unfortunately good ones aren't cheap.


      • #4
        The issue is that RCA is an unbalanced signal, XLR is a balanced signal, so you should transform from the one to the other, either with a transformer or electronically.


        • #5
          So why can't you use the RCA output on the Marantz?
          There is no advantage to using the XLR output in this case, this is not a balanced connection and won't have any of that formats noise rejection properties.. if that is what you were thinking.
          Paul O


          • #6
            Ignoring why you'd want to do this... That schematic will work, but I would not connect the shielding to the RCA side ground. The shielding will be grounded on one side, providing minimal EMI protection, and the +- signal will be transmitted to the RCA without shorting either side. This requires the RCA side equipment to be floating, so NO 3 prong power cords anywhere.

            It'll work fine, not as ideal as a transformer or active balanced to single ended circuit, but functional nonetheless.
            Electronics engineer, woofer enthusiast, and musician.
            Wogg Music
            Published projects: PPA100 Bass Guitar Amp, ISO El-Cheapo Sub, Indy 8 2.1 powered sub, MicroSat, SuperNova Minimus