Can Someone explain to me how a Ground Lift works?

Discussion in 'Amps and Cabs' started by MBreinin, Sep 19, 2008.

  1. MBreinin

    MBreinin Supporting Member

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    I am talking about the little plug adaptor with the wire and spade connector coming from it. What do you do with the spade connector?

    Mike
     
  2. MBreinin

    MBreinin Supporting Member

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    That tells me how one works with a switch to flip.

    Now, back to the question. When using one of these ground lift adaptor plugs, what do you do with the little spade connector at the end of the wire...leave it in space?

    Mike
     
  3. FrankieSixxxgun

    FrankieSixxxgun Member

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    Yup. Those are actually adapters for old style grounds in houses without 3 prong plugs. The spade connector is supposed to be screwed to the center screw of the outlet which is the old-style ground for 2 prong sockets. If you don't connect the spade to anything, effectively you have no ground. Just an FYI sometimes a faulty, ungrounded amp will whack the **** out of you.
     
  4. Adwex

    Adwex Member

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    What the OP is referring to is not a "ground lift", but a 3 to 2 prong adapter. The spade lug is supposed to be connected to the screw between the two outlets. As mentioned above, if you don't connect this, you do not have a ground. Dangerous.
     
  5. plan-x

    plan-x Supporting Member

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    Ok, call me stupid, but I have been using those things for over 30 years and haven't gotten any shocks except from touching other stuff like microphones. It certainly helps with the ambient buzzing that seems to plague the majority of places I've played. Bars, houses, theaters, churches, outdoor stages, etc.
     
  6. FrankieSixxxgun

    FrankieSixxxgun Member

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    I'd personally rather have a little ambient buzz, that you can't hear while the band is going, instead of a blister on my lip from a microphone. I sing through a custom setup inside a Shure 55SH case, which is all metal, and that thing comes at me like a tazer in houses with bad wiring. I specifically left the bridge ground off on my Tennessee Rose in case we play places like that. Keeps me from having to yell, "Don't taze me, bro," at the PA.
     
  7. cochese

    cochese Supporting Member

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    The ground lift adapter with the little tab or spade as you call it was meant not to really lift the ground but to allow you to use a 3 prong plug in a 2 prong outlet. Many old houses have 2 prong receptacles like the house I used to live in. You unscrew the screw that holds the faceplate of the wall receptacle and plug in the 2 prong adapter then line up that tab with the screw hole and put the screw back in. Now you plug your 3 prong plug into the 2 prong adapter and everything should be grounded. It's always best to check to see if an outlet is grounded with an outlet tester that you can buy at any hardware store for about $4.

    Lifting the ground on an amp is probably what you are trying to do. When you plug in two amps together many times you will get a hum because both amps are grounded it creates a ground loop. Lifting the ground on one amp should eliminate the hum but it also means there is a potential shock hazard. This is probably what you were talking about where you use the ground lift adapter as you called it but "don't" hook up the little tab. Now there is no ground on that outlet. This is not a recommended practice. I would suggest either getting an Ebtech Hum Eliminator or the less expensive Radial Bigshot ABY if this is your problem.

    If you know how you can test for shock hazards with a volt-ohm meter but it doesn't really sound like you understand the electronic aspect of grounds. You are better off being safe than sorry.
     
  8. MBreinin

    MBreinin Supporting Member

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    OK, let me elaborate why I am asking this. I have two amps connected, a regular old guitar amp and a "Mojoverb" which is like a stand alone reverb tank/re-amp combo deal. The instructions said if I was getting hum, lift the ground on the Mojo, being the lesser powered unit. I have a ground loop, because I have two amps tied together. I do get some hum, although it is not terrible. I was just wondering how to use the adaptor they included.

    Thanks,

    Mike

    p.s I think Cochese figured it out above.
     
  9. cochese

    cochese Supporting Member

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    I find it hard to believe that any company would give you this type of adapter to use unless there is something they know that I don't. First you can't get a UL rating without a 3 prong and to give you a device that defeats it would really be putting them in a position to be sued. Putting a disclaimer is fine but by including the adapter it practically defeats the purpose of the disclaimer.

    Chances are using the ground lift will work but if you forget that the ground is lifted and reach to adjust your amp or touch another piece of gear like a microphone you may get shocked. I would still say you are better off using the solutions I suggested in my previous post.
     
  10. FrankieSixxxgun

    FrankieSixxxgun Member

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    I like how they know they obviously have a design susceptible to ground noise and don't do anything to fix it aside from a band-aid solution of a ground adapter. Now that's weak! Don't other amps put a ground lift switch in their units at least?
     
  11. TD_Madden

    TD_Madden Gold Supporting Member

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    Just plug one of the amps into an Ebtech HumX. NO shocks, hum gone.
     
  12. plan-x

    plan-x Supporting Member

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    Is there a cheaper alternative, anyone?
     
  13. cochese

    cochese Supporting Member

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    If you have an old guitar cable try cutting the ground connection to one side of the cable.
     
  14. Gino

    Gino Member

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    Ground cutting on a cable didn't work in my case. Best and cleanest solution is a ground lift transformer box (like the Ebtech). I got a little Palmer transformer box, I think it's called PLI-1 that does the job superbly.
     
  15. justonwo

    justonwo Member

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    Whoever is saying that connecting that little tab to the screw on your outlet grounds your amp is DEAD WRONG. That little screw is not grounded unless the outlet is grounded (i.e., connected via a wire to earth ground underneath your house). If you have a two-prong outlet, it's there because the outlet IS NOT grounded. With a tube amp, playing with an ungrounded amp is just asking for noise or electrocution. My Champ hit me a couple of times when I touched things like metal window sills. If you are playing a tube amp, PLAY IT THROUGH A GROUNDED OUTLET. Unless you tie that little tab to a ground, it will float. The little screw on the outlet plate DOES NOT do it.
     
  16. TD_Madden

    TD_Madden Gold Supporting Member

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    Agree. $60 for the HumX is a bargain to remove ground-loop hums and avoid danger to yourself by lifting/cutting grounds.
     
  17. MBreinin

    MBreinin Supporting Member

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    It is not an issue. No hum at home.

    Also, I have a Radial ABY box that has a ground lift, so I could use that if I needed to.

    Thanks,

    Mike
     
  18. cochese

    cochese Supporting Member

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    Wrongo! If you read my post you would see I said it's best to check the outlet with an outlet tester. I apologize if I didn't make this more clear. A two prong outlet can be be grounded with a three prong adaptor but it depends on the type of wiring in the home. If you don't believe me go to Home Depot and look in the home wiring book and it will verify this. The determining factor has to do with the type of wiring in the house not the number of prongs on the outlet. If your wiring is really old like knob and tube it will not be grounded. If your house wiring is BX the metal sheath of the BX cable supplies the ground to the box. Grounded outlets are obviously what building codes require but all older homes don't have them. Even a three prong outlet may not be grounded which is why you should always check all outlets with an outlet tester.

    I did mention the Hum X and the Radial Bigshot ABY. If you use the isolation transformer of the Radial or a similar device the signal going to it must be buffered or it won't sound very good.
     
  19. justonwo

    justonwo Member

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    Quite right, cochese.
     

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