EMG pickups question -- connection to ground/earth

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by krik, May 19, 2020.

  1. krik

    krik Member

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    EMG pickups are internally grounded, rather than being electrically connected to ground through the guitar bridge.

    Does anyone know why or how EMG arrived at this design decision? Eliminating external grounding must have solved some engineering problem for them. What would be the cost/benefit analysis of internal vs. external grounding in such a design? What other manufacturers (if any) have also chosen internal grounding?
     
  2. walterw

    walterw Gold Supporting Member

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    that's not quite the right way to look at it.

    EMGs are grounded to actual ground the same as any other pickup, through the cable's ground. it's just that they're quiet enough and internally shielded well enough that you can get away with not grounding the bridge without extra noise, thus having the theoretical safety benefit of avoiding getting shocked onstage by touching a live mic or whatever.

    these days with modern PAs and modern building wiring codes i don't think there's as much risk of shock anymore, and you could just re-connect the bridge ground without it making much difference either way.
     
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  3. krik

    krik Member

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    Thank you walterw, I knew there had to be something I was missing. Habitual use of the term "internally grounded" is what led to my confusion. Maybe there is some more precise term for EMG's design?
     
  4. gtrnstuff

    gtrnstuff Member

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    I don't see any advantage to grounding the strings with EMGs.
    They work fine as intended.
    If I'd had EMGs on my guitar in Istanbul in 1988, I would have avoided a bad shock and about 9 months of very limited use of my right shoulder.
    (guitar touched a mic while both hands were on the strings, couldn't move, stage tech saw it and batted the mic stand away. about 8 seconds of loud hum in my body and numbness, until the pain hit. good times!)
     
  5. walterw

    walterw Gold Supporting Member

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    :eek:

    happy you're still here posting today!

    to be fair though, "istanbul in 1988" is probably the very definition of the situation where that kind of thing was a real problem :p

    you're correct, there's no real advantage to string-grounding EMGs, my point was just that it wouldn't make a sonic difference either way

    there are other tricks here for regular pickups, like using a really big capacitor or even a really small fuse in line to the string ground so as to block DC while still doing the job of reducing noise
     
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  6. gtrnstuff

    gtrnstuff Member

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    Thanks, nice to still be here. The doctor that soon arrived was surprised to find me alive and conscious (through an interpreter).
    You got that right. We had just done shows in Germany, with all the technological order and precision you would expect, and then we landed in Turkey. Different world. Plus my fly rig was on a step-down transformer to get what I assume was close to 120v instead of the house 240v.
    I'll say this, after years of hearing hum based on 60 Hz, 50 Hz sounded (and felt) very different.
    Afterwards, I found schematics for those shock-reducing circuits you mentioned and put them in the ground path of any guitars I was going to use in suspect conditions.
    Another tip I heard, don't grab the mic while holding the strings. If you don't have a meter, touch it with the back of your hand, so any muscle contractions won't make you grab on to it. If you feel any current, address the grounding issue.
     
    Last edited: May 22, 2020
  7. walterw

    walterw Gold Supporting Member

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    oh yeah.

    i suppose one could just touch the guitar strings right to the mic and watch for sparks :confused:
     
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  8. Timtam

    Timtam Member

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  9. gtrnstuff

    gtrnstuff Member

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    I saw the strings burn right off a guitar in a basement here in TN in 1978. My band mate's amp was plugged into a 2-wire outlet and brushed his Tele against a steel support pole.
    Oops, should have flipped that ground switch, but who knew? Thankfully nobody got hurt that day.
     
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  10. BluntForceTrauma

    BluntForceTrauma Member

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    This is why I go wireless live. Takes me out of the circuit.
     
  11. walterw

    walterw Gold Supporting Member

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    anybody who worries it would "hurt the value" to convert their vintage 2-prong wire amp to grounded 3-prong and remove the "death cap" needs to read this
     
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  12. RicOkc

    RicOkc Member

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    I had an incident with grounding issues at a gig in the late 70's.

    I went to my microphone to do a back-up vocal and my band-mates saw a blue spark jump from the mic to my face. I didn't pass-out, but I did slightly black-out when it happened.

    From then on I carry a outlet checker in my gear bag.
     
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