Mic Shock - Can the Guitar Be the Culprit? (Aside from Amp, etc.)

Discussion in 'Recording/Live Sound' started by jasburbak, Mar 29, 2015.

  1. jasburbak

    jasburbak Member

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    Recently I went to a new practice/recording studio, with my newly built Tele/Jazz Partscaster. When doing vocals, I got the much known "little shock" upon touching the mic while singing. Nothing drastic, but still a zap each time my lips touched the mic.

    Like many threads discussed before, I suspected the Amp, Outlet, or PA mixer not being grounded to the same outlet as the Amp, etc..

    However, since this was a new partscaster built, I thought "maybe, the guitar might have something to do with it?"

    So, I tried with the lead guitarists guitar, and nothing happened. No zap. Which made me curious.

    -I have a ground wire running from bridge to back of vol pot for grounding.

    -I did the rest of the session with a foam windscreen, but thats still not comforting me much.

    -I live in Europe, 220v (so amp prongs are if i am not mistaken, have ground on the plug).

    What gives? :dunno
     
  2. jmoose

    jmoose Member

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    This seems like WalterW question... but is it possible that maybe the leads to the output jack on the partscaster are reversed? In theory that could put voltage to ground.
     
  3. Cosmik de Bris

    Cosmik de Bris Member

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    Did you swap guitars and plug into your amp or did you use his guitar and amp?
     
  4. jasburbak

    jasburbak Member

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    I'm pretty sure I wired the leads correct, but i'll recheck, no harm in that.

    I didn't even think of that until you said it - I used his guitar and amp. That would narrow it down more I assume.
     
  5. SteveO

    SteveO Member

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    The guitar isn't the culprit. The voltage coming out of the wall is reversed on either your guitar amp or the PA. This can, and has, killed people, so don't take the issue lightly.
     
  6. jasburbak

    jasburbak Member

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    I'm definitely not, first thing that came to mind as soon as I got zapped was Keith Relf.

    Could you elaborate that a bit further, just for the sake of knowledge; When you mean that the voltage is reversed (from either the amp or PA) are we talking about the polarity switch? Or is it, in theory, the outlet wires being reversed, same as one might accidentally reverse the leads on a jack?

    Since when I swapped guitars with my lead guitarist, and both of us were plugged into the original amps we first did, and no zap - then that would isolate the problem to the amp i was hooked up to. If it was the PA system, then I would've gotten zapped with his guitar as well. Does my reasoning make sense?

    Just to clarify my original curiosity as well, is there anything that could be present on a guitar that would be the sole cause of such an event? Or in such cases of getting shocked, is it always either the amp, outlet, PA, etc.. ?
     
  7. SteveO

    SteveO Member

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    The shock is coming from the reversed 120V on either the amp or PA, which effectively makes the chassis on one or the other 'hot'. When you're touching a grounded component on your guitar (which is electronically linked to your amp), and then you touch the mic (which is electronically connected to the PA) with another part of your body, you are effectively providing a source of continuity between the amp and the PA.

    Think of it as the same thing as dropping a wrench across the posts on your car battery-there's going to be sparks and the wrench is going to go flying.

    In your situation, you are the wrench.
     
  8. RCM78

    RCM78 Member

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    The OP says he's in europe and everything is 220 volt. It's possible the L1 and L2 legs are reversed on one of the plugs, or theres no neutral/ground on the circuit.

    Also make sure the ground on your amp isn't lifted!!!
     
  9. jasburbak

    jasburbak Member

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    Thanks for the explanation SteveO :aok

    The amp is not mine, it was one of the ones in the recording/practice studio. A Marshall 3xxx something, don't remember exactly. But i'll definitely be telling them to have it fixed immediately, in the meanwhile, i'll just tell the lead player to use that amp, he's been playing too many solo's anyway.. :p

    Anyone have an idea or answer to the question posed above about a guitar itself ever having the sole responsibility in a similar situation? (wiring/grounding, etc..)
     
  10. SteveO

    SteveO Member

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    My bad, I missed the 220 part.

    The guitar won't be the cause of it, it's just transmitting the problem through to your body.
     
  11. bob-i

    bob-i Member

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    If it's just a little tingle, its most likely some voltage leakage to ground caused by the amp. If it was voltage reversal you'd have the full 220AC hitting you, it would be unlikely you'd be around to post this thread.
     
  12. J M Fahey

    J M Fahey Member

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    Don't know where you are exactly but since forever Europe used 2 round leg mains plugs which could be plugged both ways.

    The must be still millions or tens of millions of homes still wired the old way, your rehearsal studio might be in such a building.

    Death caps were never loved in Europe but simple "losses" in insulation may let pass a couple mA , not enough to kill but definitely felt, doubly so in such a sensitive area as lips.

    Probably unplugging one of those amps and inverting the plugs could have avoided or minimized the tingle.

    A customer of mine almost died (was rescued by a fast thinking and acting member of the public) when playing Bass for a well known Tango singer who at the end of a song fakes fainting and "drops" her microphone, which is "rescued" by the Bass player.

    He grabbed it with his left hand while muting the bass strings with the right one.

    Both amps (PA and Bass) were Peavey, we have 220V lines, had ungrounded European mains plugs, and I guess both amps had the "phase/polarity" switch flipped opposite ways.

    Same happened to a Musician I know, less than a year ago, in Recife, Brazil:
    https://www.youtube.com/watch?v=vqMehAA2Fso

    he was saved because his guitar strings touched the microphone stand and that short bypassed his chest.

    By the way, Brazil has 110 and 220V systems, sometimes in the same city, and both use either American parallel flat blades or round European pins, both can be plugged both ways.
     
  13. billyguitar

    billyguitar Member

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    Use a foam cover on the mic.
     
  14. ejanuska

    ejanuska Member

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    Maybe the mic has some wiring issues, try a different one.
    You might have a problem with the shield in the mic cable, try another, test the cable.

    If there was 220VAC on the mic you would know from the burn marks on your lips, not to mention the mic would have probably died.
     
  15. jasburbak

    jasburbak Member

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    Yup, it was just a little tingle each time my lips touched the mic, nothing that would've bothered me except for the implication that it might've been dangerous. As far as I gather if it was the more notorious "shock" then I wouldn't be here to post this query, so that's a relief ;)

    I'm in Istanbul, so we use the common 2 round mains plug that can be plugged both ways, I'll try inverting the plugs next time I'm there to see if that makes a difference, but I assume it is just like you said, it makes sense that a lot of the buildings here are wired the old way. 110v and 220v both in in the same city? That must be a nightmare :huh

    I also did try another mic, and same thing happened, so the the cable itself could be the issue as well, like said. That's when I used the foam cover for the time being.

    Thanks to everyone who answered, much appreciated :aok

    Here's one last question, I wast thinking of getting a non contact voltage meter (the ones shaped like a pen), to test and see if the mic cable, amp cable or outlet has an issue, to isolate the problem. Would that work (excuse my ignorance of electrical knowledge), or would it just show the current running through such devices, like it should?
     
  16. Cosmik de Bris

    Cosmik de Bris Member

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    Was he plugged into a different outlet? In our country the regulations are pretty tight so we don't get earthing problems often but they do happen. We always make a habit of running all the sound gear off of one outlet, no earth loops so no hum, and it reduces the shock problem.
     
  17. mattball826

    mattball826 Member

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  18. jasburbak

    jasburbak Member

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    I assume so. His amp was across the room, although I do not know how the studio is setup, so they might all be connected to the same outlet somewhere, although in this case highly unlikely. Yeah, unfortunately safety regulations aren't governed in Istanbul or most parts of Europe as it is in the States.
     
  19. J M Fahey

    J M Fahey Member

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    Always carry a small neon lamp electrician screwdriver, with one hand touching your instrument strings, test the mic with the other:

    [​IMG]

    If it lights, there's more than 100V difference , as simple as that, invert one of the plugs and see whether it goes down.

    Which one? Your amp or the PA one?
    Try both, one combination will be better than all others.

    The cable itself is not the culprit, but the PA at the other end.

    Side note: liked Istanbul very much, maybe I'll be visiting in July :)
     
  20. Cosmik de Bris

    Cosmik de Bris Member

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    Actually I'm in New Zealand :) Don't take chances with this, you can end up dead. Some of these other solutions like using a Mic shield etc are all very well but they don't solve the basic problem which could get you killed.

    Take care.
     

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