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Bridge/strings ground

Discussion in 'Pickups & Electronics [BG]' started by subdude67, Nov 27, 2012.

  1. subdude67

    subdude67

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    grounded bridge and strings, i read a lot about how it MUST be done with passive basses and not with active, i understand that the grounded bridge could potentially lead to an electric shock,yet without it there will be noise and hum so it has to be there. but.......

    ....i have recently converted my 5 stringer from active to passive and without a grounded bridge it is dead quiet. i am of course very happy about having an instrument with no hum or buzz but i am also a bit perplexed as to what the story really is with the grounding.

    any thoughts are appreciated.
  2. slngd

    slngd

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    I am no expert, but i doubt that a 9V electric shock would be that big of a deal.
  3. Smilodon

    Smilodon Supporting Member

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    Grounding the bridge is a preventive thing. You could get buzz in a noisy environment. It can be dead quiet when you are at home, but if you go to a gig it could buzz really badly.

    It's not the battery that can give you a shock. It's the voltages built up by differences in ground potential or electrostatic shocks.
  4. wcriley

    wcriley

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    Back in the late 70s or early 80s Guitar Player Magazine had an article that recommended putting a capacitor in series with the bridge ground. The idea was that the cap would prevent shocks by blocking 60 Hz AC, but still pass higher frequency EMI "noise" to ground.

    Any comments on this?
  5. jacojbass

    jacojbass Supporting Member

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    just do the ground, might save your life.....just saying
  6. subdude67

    subdude67

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    isn't it actually safer NOT to be connected to the circuit with regards of a potential electrocution?

    what good is a bridge ground anyway if, like in my case, nylon tapewound strings are used?

    thanks for taking time
  7. wcriley

    wcriley

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    Yes.
  8. ctmullins

    ctmullins Registered 8er Supporting Member

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    Wow, there are still a lot of misinformed people out there...

    Most definitely, the safer option is to NOT be connected to a potentially lethal electrocution hazard.

    To the OP - there are no absolutes. Don't think in terms of "must" or "can't", because that's not how the world works. It's entirely possible to have a quiet instrument without a bridge ground, and vice versa. Most of my own instruments omit it, and are reasonably quiet under most circumstances due to cavity shielding everywhere else. The bridge ground is a quick and easy way for mass producers to silence their mass produced instruments, but there are better methods for those willing to take the time.
  9. lucam

    lucam

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    Please tell me! I find this subject to be very interesting :)
  10. ctmullins

    ctmullins Registered 8er Supporting Member

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    Meticulous shielding. I use the copper foil from StewMac, but it's important to make sure that there is good connectivity between adjacent strips of foil. The adhesive is supposed to be conductive, but I've frequently found, with a multimeter, that there was too much resistance between strips. A spot of solder at the junction will remedy this.

    Be sure and follow all of the other best practices regarding shielding as well. There are lots of good shielding tutorials out there - there's even a sticky right here at the top of this forum. Shield the pickup cavities as well as the main electronics cavity, and connect the two with a ground connection of some sort. Eliminate ground loops by using star grounding. That should do it.
  11. Smilodon

    Smilodon Supporting Member

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    Nylon tapewound strings still have a steel core and metal ball ends AFAIK. They'll still work as an antenna.

    You will be insulated from shocks as long as you don't touch the bridge or pots, though. :)
  12. Bobster

    Bobster

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    subdude67,

    Is this your Yamaha RBX375? The stock pickups are humbuckers. I believe this is why your bass is quiet without the bridge ground.

    All the best,

    Bob
  13. subdude67

    subdude67

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    thanks to all for your contributions!

    yes, it is my RBX375. do you think it would still be so quiet even if it was not shielded and grounded properly? i thought i did such a splendid job with the shielding/grounding:crying:

    with regards to the nylon tapewound strings, my remark was not about the strings being like an antenna, it was about being insulated from the bridge ground and thus not be able to stop the buzz by becoming the ground myself.
  14. abemo

    abemo

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    Another way to ensure connectivity between all strips of shielding is to fold over about a quarter inch of the tape and drive a small screw through the overlapped sections. This is also a good spot to anchor your eyelet for the rest of your equipment grounds in a star grounding system (aka, backs of pots, bridge if you ground it, etc)

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