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Question about "getting 'shocked' by an amp", and active vs passive electronics

Discussion in 'Pickups & Electronics [BG]' started by kumimajava, Aug 14, 2017.

  1. kumimajava


    May 19, 2010
    Tokyo, Japan
    Sorry if this is a stupid question, but I couldn't find a direct answer using the search here.

    I've read a few threads on here when someone has said they got "shocked/zapped" by their amp, and somewhere down the thread someone points out that this may be potentially lethal, the amp is incorrectly earthed, etc.

    Usually it's pointed out that this is particularly dangerous on basses with "passive" electronics. So far, this all seems to make sense to me.

    The residual question I have is: if an amp is incorrectly grounded, is the likelihood of getting "shocked" by it less on a bass with an active preamp? And if so, which part of the active pre-amp reduces the risk of shock?

    Obviously i'm not asking to ignore proper grounding in the amplification chain, but I was just curious to understand a bit more about the stuff we're playing with daily.

    Thanks in advance for any input :)
  2. Bruce Johnson

    Bruce Johnson Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    It makes no difference. Either a passive or an active instrument can potentially shock or electrocute you, if there's a fault in the amp, and the amp isn't properly grounded. The high voltage travels out through the ground side of the amp, through the shield of the cord, to the ground side of the instrument's output jack, and to the bridge and the strings. Then, if you connect yourself to a ground, such as standing in a puddle of water or grabbing a mic stand that is grounded, the current passes through you, and you get zapped. Passive electronics aren't going to stop anything. The ground side of the output jack is still connected to the strings.
    kumimajava likes this.
  3. kumimajava


    May 19, 2010
    Tokyo, Japan
    Thanks for the response - all info I was looking for :)
  4. The reason some people think you won't get shocked with an active system is that some of those actually don't ground the bridge to the controls. So, you couldn't get shocked by the strings, but you could still get shocked by the controls, if they have conductive knobs.
    kumimajava likes this.
  5. kumimajava


    May 19, 2010
    Tokyo, Japan
    That's interesting - not heard of an un-earthed bridge on an active installation before :) Learned something new!

    Now off to find a thread on the vices & virtues of grounded vs. un-grounded bridges - I'm sure someone must have already asked that question!

    Thanks again :)
    Killed_by_Death likes this.

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