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417 Views 10 Replies Latest reply: Mar 5, 2012 4:44 AM by jimsreynolds RSS
bassmanatum Just Startin'
bassmanatum
3 posts since
Nov 16, 2010
Currently Being Moderated

Mar 2, 2012 6:10 AM

Getting Shocked

Hello everyone! I searched the forum for a while a didn't find anyone else having this problem. If I use a wired mic while playing my electric through the HD500 I get shocked by the mic (a knock you out kinda shock). I didn't have this problem before the HD500. Any suggestions?

  • phil_m Expert Line 6 User
    phil_m
    4,243 posts since
    Jan 25, 2007
    Currently Being Moderated
    Mar 2, 2012 6:22 AM (in response to bassmanatum)
    Re: Getting Shocked

    If I understand correctly, you're using a mic not attached to the HD500, right? Do you have your HD500 connected to an amp or through a PA? It sounds like there's a loose ground wire somewhere in your system or something that's not grounded properly. Can you give a little more detail on everything you have connected - what all do you have the HD500 hooked up to, and what is the mic connected to?

    • bassmanatum Just Startin'
      bassmanatum
      3 posts since
      Nov 16, 2010
      Currently Being Moderated
      Mar 2, 2012 7:44 AM (in response to phil_m)
      Re: Getting Shocked

      I have my guitar ran to the HD500 (1/4") and the HD500 connects to our board by xlr (Left only and no amp). The mic is ran to the board by xlr as well. I have used the Hd500 in several rooms/buildings now but it always does the same thing. I figure like you that it is a grounding problem. Would it matter that the unit does not have a ground plug? Or could it be the ground on my guitar?

      • silverhead Expert Line 6 User
        silverhead
        9,592 posts since
        Apr 1, 2009
        Currently Being Moderated
        Mar 2, 2012 7:50 AM (in response to bassmanatum)
        Re: Getting Shocked

        I don't know if this will make any difference, but have you tried using the GRND LIFT switch on the HD500?

      • phil_m Expert Line 6 User
        phil_m
        4,243 posts since
        Jan 25, 2007
        Currently Being Moderated
        Mar 2, 2012 8:02 AM (in response to bassmanatum)
        Re: Getting Shocked

        Well, does your PA have third prong on the plug? Honestly, I think the problem is more likely to be on the PA side than the HD500 side. There isn't really much to the HD500's grounding system since it's a low voltage piece of gear. It probably only conists of conductor to bond the board to the chassis. But from the PA side, it could be a number of things. How is the PA powered?

         

        The other thing that you should try to do is make sure that everything is plugged into the same circuit. This will minimize the possibility of different paths to ground developing.

        • bassmanatum Just Startin'
          bassmanatum
          3 posts since
          Nov 16, 2010
          Currently Being Moderated
          Mar 2, 2012 6:23 PM (in response to phil_m)
          Re: Getting Shocked

          The board is ran through a conditioner (front of house) and the amps are ran through a seperate conditioner (back of house) and everything is ran with the ground ground plug (three prong). I have ran the Pod unit both ground and lift and doesn't seem to change much. I do not get shocked on the lips from the mic unless I am touching the guitar strings.

          • phil_m Expert Line 6 User
            phil_m
            4,243 posts since
            Jan 25, 2007
            Currently Being Moderated
            Mar 3, 2012 6:35 AM (in response to bassmanatum)
            Re: Getting Shocked

            If possible, you should try to plug the POD into the power conditioner powering the mixer.

             

            Basically, how this develops is that since the HD500 is being powered from a different circuit than the mixer, it will be at a slightly different potential than than the mic. And since you have the mix and the HD500 plugged into the mixer, you have two parallel grounding paths at different voltage potentials. So when you touch the guitar strings and the mic at the same time, you are closing this circuit, allowing current to flow from one to the other. This isn't really all that uncommon for guitarists using mics, and it can sometimes be caused by an actual loose ground connection, but it might not be.

            • BMoe Just Startin'
              BMoe
              62 posts since
              Feb 7, 2010
              Currently Being Moderated
              Mar 3, 2012 2:11 PM (in response to phil_m)
              Re: Getting Shocked

              1+ to phil_M

               

              This use to happen to our band alot, IF the PA (mixer) and a guitar set up is on different AC circuits, you can get a "zap" on the lips from the mic,

              when touching your guitar strings. Thats why we would run all the AC power from the same outlet (we had tons of equipment) never a problem,

              even on a 15 amp circuit. When playing at various venues, there is really no easy way of knowing what outlet is coming from what side

              of the service box, but as phil_m stated, there is a difference of potential between the two sides(legs), that could cause the lips to tingle (not fun).

              If there was a grounding problem, I would see 60VAC between the mic (where the lips would touch) and ground (measured with a multimeter).

              That's enough to bite.

              So in closing, check out those two things, one or both could be the culprit.

              • albertpike2000 Just Startin'
                albertpike2000
                37 posts since
                Feb 12, 2010
                Currently Being Moderated
                Mar 4, 2012 9:09 AM (in response to BMoe)
                Re: Getting Shocked

                Phil M. With all due respect this used to be common but in a properly grounded system should never occur. The fact that he reports a "knock you down" shock in itself is disturbing. There is something bad wrong and dangerous going on. Serious troubleshooting is needed. Maybe an electrician could test all of the ground circuits and show you how to do it yourself

                • phil_m Expert Line 6 User
                  phil_m
                  4,243 posts since
                  Jan 25, 2007
                  Currently Being Moderated
                  Mar 4, 2012 9:17 AM (in response to albertpike2000)
                  Re: Getting Shocked

                  I agree with you. It's unfortunately not uncommon to run into unproperly grounded system. I actually design electrical systems for buildings as a living, so I've seen a little bit of everything. I guess I overlooked the "knock you down" part. I do really wonder if there is loose ground conductor in the HD500 somewhere.

                   

                  But really, even in a properly grounded system when you have two parallel grounding paths, it's possible for voltage potentials to be slightly different on each path.

                  • jimsreynolds Power User
                    jimsreynolds
                    2,227 posts since
                    Jun 27, 43450
                    Currently Being Moderated
                    Mar 5, 2012 4:44 AM (in response to phil_m)
                    Re: Getting Shocked

                    Is the Mic phantom powered?  Does it need to be?  Can you switch that off?

                     

                    I once got told that on a battleship the potential difference between grounds at two points in the ship could be hundreds of volts but I guess that probably isn't relevant here.

                     

                    I think in bassmanatum's shoes I would start off with

                     

                    • Checking the Phantom Power situation
                    • Taking a multimeter voltage reading between the Mic and guitar strings - always useful to know how badly it is trying to kill you.
                    • Try Phil's test of plugging the HD into the power conditioner for the desk and taking the same reading.
                    • Try changing out the mic cable and take the same reading.
                    • With all that good information in hand:  I would probably go and get an electrician to look at the earthing on the HD anyhow.

                     

                    At a push:  I suppose you could run a cable lead from the HD chassis to the Mic as a temporary thing.  At least then you are not the ground.  Not a safe solution though so I would not recommend it ... at all.

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