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XLR Cables - Connection to the case

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  • XLR Cables - Connection to the case

    MEF members....

    I have a dozen or so XLR cables, all wired up, no noise, life is good.

    I just came a cross a brand new cable, a brand X, where the case of the XLR is wired to pin 1 - ground.

    I believe the consensus on XLRs is that you do NOT connect the case of the connector to the ground pin. I have a handful of new cables where that is the case. But this one in particular does have that connection. Is there a scenario or application where it is helpful (desired, recommended, etc etc etc) where you DO want the case grounded?

    Thanks in advance.

  • #2
    In use, when the random XLR cable is connected to Microphones, or mixer, outboard gear and such, the chassis (or body of the microphone) makes contact with the shell of the connector, so that shielding i, s extended over the wiring inside the connector. The main issue is when cables are connected to each other, or to a snake breakout, laying on the ground, be it concrete, dirt, what have you....that's where you don't want the shell connected to the shield, which can introduce noise/ground loops.
    Logic is an organized way of going wrong with confidence

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    • #3
      Yes, connecting the shell to pin 1 can cause ground loops, and in fact can effectively disable a 'ground lift' switch on the connected equipment.

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      • #4
        Thanks guys.... I appreciate the replies.

        I guess this particular cable is a cheap one-off. So this is something I will check on ALL my cables and anything that comes through the front door in the future!!

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        • #5
          All these ideas are POTENTIAL problems. If your differently wired cords are not making hum, then why go through and rewire them?
          Education is what you're left with after you have forgotten what you have learned.

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          • #6
            Enzo.... this cable was noisy. I found a wire barely connected to a terminal (pin 2). After soldering that connection, the noise was still present - at least noise I could hear and in relation to other cables (using my mixer, external effects, etc). So I removed the strap and that seemed to do it. I always check cables, equipment before taking them out to a gig. So that is how I noticed this one.

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            • #7
              I always check them, too. I got a batch of XLR cables once and the cable shield was connected to pin 3 of the connectors on every cable. The cables were obviously very noisy, but tested good on a cable tester. The problem is that a cable tester just checks pin to pin continuity, so it doesn't know if the shield is soldered to the wrong pins.
              "Yeah, well, you know, that's just, like, your opinion, man."

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              • #8
                FYI In these matters I've always found this "white paper" on balanced audio from Jensen Transformers to be quite useful,
                https://sound-au.com/articles/balanced-interfaces.pdf

                the relevant discussion of cables begins on p 13!

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                • #9
                  Rane Tech Note 110 is another good one.

                  https://web.archive.org/web/20190825...connection.pdf
                  "Yeah, well, you know, that's just, like, your opinion, man."

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                  • #10
                    Thanks guys... good reading !

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                    • #11
                      Originally posted by The Dude View Post
                      Rane Tech Note 110 is another good one.

                      https://web.archive.org/web/20190825...connection.pdf
                      I was horrified when I discovered recently that Rane’s technical library had been taken down. All that good stuff, no longer deemed worthy
                      My band:- http://www.youtube.com/user/RedwingBand

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                      • #12
                        About Rane

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                        • #13
                          Originally posted by pdf64 View Post
                          I was horrified when I discovered recently that Rane’s technical library had been taken down. All that good stuff, no longer deemed worthy
                          Agree. I had to do some searching to find a link to that one. At least my old brain still remembered what tech note number to search for.
                          "Yeah, well, you know, that's just, like, your opinion, man."

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                          • #14
                            I read through the link in post #9, but I still have questions. Are the case and pin #1 ground connected inside a microphone ? What about when you use an XLR cable as an extension to a microphone cable ? Aren't the shells floating in that situation ? What if the shell is connected to pin #1 only at one end of the cable ?
                            WARNING! Musical Instrument amplifiers contain lethal voltages and can retain them even when unplugged. Refer service to qualified personnel.
                            REMEMBER: Everybody knows that smokin' ain't allowed in school !

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                            • #15
                              I just checked my microphones... the dynamic ones anyway. The case of the microphone does connect to the ground on pin 1. So that means the case of the mic cable connector (at that end) is grounded. But, the other end is not "tied" or connected to that same point. What happens at the other end depends on the mixer, snake, etc.

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