Guitar Grounding Common Misconceptions?

Discussion in 'Tonefreaks' started by jonesy, Jul 23, 2010.

  1. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    I see a lot of posts concerning the different types of grounding used in electric guitars from the wire in the cavity that runs to the tailpiece, or the metal plate that the long shaft pots are mounted to or even the solid ground loop wire used in vintage LP rigs.

    There are two types of grounding in your guitar. One type grounds the hardware, strings, switch frame etc. and has nothing to do with the way your volume and Tone controls or input jack works.

    The other type is the lugs on your pots that are soldered back to the case, or the "Ground Buss" or "Ground Loop" wire that connects your pots together, or the metal plate that actually acts as a means of grounding the pots together in the factory Long shaft LP harness's, or the ground wire to you input jack.

    The two types of grounding do make a connection, but serve different purposes. Here is a post from a recent thread that will explain some of the things I am trying to clear up here.



    From this thread:
    http://www.mylespaul.com/forums/tonefreaks/98558-grounding-predicament.html




    THE TWO TYPES OF GROUNDING...

    The outside lug on your volume pots is part of your circuit ground, without them your volume controls will not work right because the signal will not shunt to ground and your volumes will not turn down a ll the way.

    The lug soldered back to the case on your Tone pots is part of your circuit and without it your Tone control will not function properly, another shunt to ground

    The wire from your switch lug has nothing do do with your signal and only grounds the frame of the switch. Your volume and tone controls will still work without it.

    The ground wire from your tailpiece studs grounds your bridge, strings, and stop tailpiece and has nothing to do with the way your volume and Tone controls function and they will work without it.

    Your pickups each have a ground wire soldered to the back of the volume pots, without that ground your pickups will not work.

    If the ground wire to the tailpiece studs is wired properly you will notice some noise go away when you rest your hand on the strings. This also depends on how much gain you have on your amp at the time.

    If you touch the strings or metal hardware on your guitar and the Buzz/Humm get's louder you probably have the + and - reversed on your input jack.

    The ground wire that is soldered to the back of your pots is a critical part of your volume and tone circuit and your controls will not work without it unless you have the metal plate installed.

    The ground that goes to your input jack must be connected to the back of your pots grounding it into the circuit. It is the neg. - side of your signal and your guitar will not work without it.


    Many of you veteran tinkers probably already know most if not all of this, but for some of you new guys I just wanted to try and provide some info about grounding.


    As far as "Buzz" & "Humm" Faulty cords and partial, shorts are often the culprit of this as well as bad AC power. But good solder joints, and understanding how things go together properly will help you have a much quieter guitar in the long run.

    Keep this in mind whenever you replace pu's or any of the other electrical components in your guitar. Happy Modding and keep the music flowing (without the humm) ;)
     
  2. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    I thought a few pics might help out...

    [​IMG]
    Grounding on a vintage 50's style LP harness using solid tinned 20 awg copper wire


    [​IMG]
    Braided wire grounded to the switch lug and also grounded to each other on a Switchcraft LP toggle switch


    [​IMG]
    Vintage 50's style LP wiring diagram showing grounding for braided wire and ground loop to back of pots.


    [​IMG]
    Gibson Studio LP with long shaft pots and the metal mounting plate acting as a ground for all 4 pots. You can also see the center post where input jack leads and hot lead from switch are connected.




    [​IMG]
    Another pic of the metal plate in a Gibson LP, notice the junction of wires on the middle center post. That is where hot from switch and hot and ground from input jack are connected. If the metal plate is removed those connections have to be re-vamped. You can also see the braided wire from the pickups grounded to the back of the volume pots.
     
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  3. FourT6and2

    FourT6and2 Senior Member

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    All good info, but at least in the thread I started I was talking only about the ground wire from a pot to the bridge/tailpiece/strings. When I said "grounding predicament" that's what I was talking about - grounding the circuit to the strings and therefore through the player. Since that's what was getting rid of the noise - touching any metal component that's part of the circuit, like the output jack, a pickup or the switch ring. Could it be a problem with one of the other "grounds" in the circuit or a bad solder joint? Maybe. I don't know yet.
     
  4. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    Thanks, glad you like the info. And yeah I know what you meant in your original post, but then a lot of other questions about grounding seem to arise that people were not clear of.

    And true, when the strings are grounded (via the wire that runs from the tailpiece studs) that touching them will deaden some of the extra noise. But what is causing that noise to begin with? Most likely a bad ground, cold solder joint or partial short. Take care of that problem and the buzz will go away with or without the string ground.
     
  5. b-squared

    b-squared Banned

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    Great thread, Jonesy...it's now a sticky thread. :D

    BB
     
  6. FourT6and2

    FourT6and2 Senior Member

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    Yep, hopefully I'll get it sorted. :)
     
  7. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    Thanks BB, that's cool :D
     
  8. MrRhoads

    MrRhoads Senior Member

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    Great to see a grounding thread :D
     
  9. tazzboy

    tazzboy V.I.P. Member

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    Here is Billy from RS Guitar works demo on how to do it.

    [ame=http://www.youtube.com/watch?v=UPvpLuSaOOQ&videos=mICl5j9kgK8]YouTube - How To Wire A 3 Way Switch[/ame]

    [ame=http://www.youtube.com/watch?v=dqmioqe-_Xo&videos=xUweZOTZyc0]YouTube - RS Guitarworks: How To Assemble RS Vintage Kit[/ame]

    [ame=http://www.youtube.com/watch?v=ml0zHsIaMEY&videos=dqSFinoLbBo]YouTube - RS Guitarworks: How To Solder Ground Connections[/ame]
     
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  10. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    Billy does a nice job for sure. Good soldering skills and proper assembly work will make the difference between a noisy rig that buzz's to a quiet one that really sounds great ;)
     
  11. FourT6and2

    FourT6and2 Senior Member

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    Well, I sure as hell am not bringing my guitar back to the tech who put the pickup in, that's for sure. I found a new guy. He's a roadie/tech for Metallica. So, hopefully he does good work.
     
  12. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    I hope this new guy takes care of you and does a good job, but to be honest if you can learn to work on your own guitars you will not only save money but you won't have to leave them with somebody else and it may save you headaches in the long run.

    I understand that not everyone feels comfortable working on a $2000 LP, but I think it is important to try and do as much as you can. The more you do, the more confidence you will have and there is also a sense of pride that you will get from working on your own guitar. ;)
     
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  13. brianugly

    brianugly Senior Member

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    Great thread Jonesy, I learned a lot!
     
  14. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    Thanks Brian, glad to hear that. :thumb:
     
  15. Raz59

    Raz59 Senior Member

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    Ground loop (electricity) - Wikipedia, the free encyclopedia

    "In an electrical system, a ground loop usually refers to a current, generally unwanted, in a conductor connecting two points that are supposed to be at the same potential, often ground, but are actually at different potentials. Ground loops created by improperly designed or improperly installed equipment are a major cause of noise and interference in audio and video systems. They can also create an electric shock hazard, since ostensibly "grounded" parts of the equipment, which are often accessible to users, are not at ground potential."

    Now jonesy, I understand when you say "ground loop", you're referring to the shape of the solid bus wire.
    Non the less, in terms of semantics you're using an ambiguous thing, and it may lead to confusion (this applies to other terms such as "full sized" pot and "braided 2-lead").

    Further, if you look at how in the olden days people soldered the toggleswitch on a Les Paul:

    [​IMG]

    The middle braid shield comes from the jack, which means that is the actual ground and the one you put a PVC cover on in the control cavity (to avoid grounding then what's wanted). If you solder all 3 braids together, then all 3 braids become a path to ground.

    Which means that, in these pictures:

    [​IMG]
    [​IMG]

    The bus wire from Bridge Tone to Neck Tone is completely unnecessary. Now THAT is a true ground loop, it's an extra connection to ground...and both of the pots are already grounded by the wires coming from each volume pot.

    The AC current produced by strumming the strings on an electric guitar is very small, but still, is it a good idea to be telling people to wire a ground loop?
     
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  16. FourT6and2

    FourT6and2 Senior Member

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    Raz, what's interesting is some RS kits come with that "ground loop" wire connecting all the pots and some come with out it (bridge volume/tone connected and neck volume/tone connected, but bridge not connected to neck).

    I think it depends on how you wire the rest of the guitar. For example, my guitar (stock) has a metal ring in the switch cavity that the switch gets grounded to. There is no ground wire wrapped around all three leads.
     
  17. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    [​IMG]


    The main reason that all 3 braided leads from the switch are soldered/grounded together in the 50's wiring is that's is how the ground from the back of the pots is routed to the input jack through the braided lead.

    Without that connection there at the switch there would be no ground going to the input jack. The ground from the switch lug is just a "hardware ground" the input jack has to be grounded to the "circuit" so the braided provides the "ground" to complete that.

    The modern wiring has the the input jack lead run to the center post ground or just soldered right to the back of one of the pots. The 50's wiring has the ground run from the pots to the switch then to the input jack. Hope that clears things up.


    [​IMG]

    And you also have to consider that many times the switches in many LP's have the color coded PVC wire so the ground path is not the same as with the 50's style braided wire to the switch so the "ground wire" on the back of the pots is necessary. Do you follow me?
     
  18. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    You can see in this pic of one of my 21 Tone Jimmy Page rigs that the ground to the input jack comes right off the back of one of the pots. This connects it into the "circuit". Then the hot to the input jack is supplied by the red wire from the switch.

    The green wire from the switch is connected to the ground lug on the switch providing the "hardware" ground and it solders to the back of the bridge volume providing an additional grounding point.

    The black and white wires from the switch connect to the hot lug on each volume pot. Black goes to the bridge volume and the white wire goes to the neck volume.

    Depends on what variation of wiring you are using as to how the ground is routed to the input jack. As long as it get's there that's what is important ;)


    [​IMG]
     
  19. Raz59

    Raz59 Senior Member

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    So when you say "ground loop", you're describing the path of the wire to ground? Is that it?
    Do you see why using this term so freely causes confusion? Now you have 3 possible meanings and only one of them is an electrical term and denotes an error!

    I understand how this old styled wiring works. And the fundamental part of it is that the braided metal that is outside of the conductor wires is supposed to be a path to ground.
    The purpose of the braid is to act as a shield to outside interferences.
    Seeing as the braid is a path to ground and that an electric current chooses the shortest path to ground, the braid should not come in contact with any other wire, or it'll cause a short circuit.

    You describe the path to ground as "ground loop", ok.

    [​IMG]

    By removing the piece of wire between BT and NT, you have this shape. Do you call this a "ground trident"?
     
  20. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    The metal mounting plate is actually a "grounding point" as well ;)

    [​IMG]
     

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