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Guitar ground loop 101?...

Discussion in 'Tele-Technical' started by Boolywho, Jan 24, 2011.

  1. Boolywho

    Boolywho Tele-Meister

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    So I'm a little confused about the whole ground loop thing in reference to guitar circuits. :eek:

    With this in mind, I have a few questions:

    1) Can ground loops theoretically form in the first place in a normal guitar guitar circuit (e.g. a telecaster circuit)

    2) Assuming they can form, what wiring configuration sets this situation of potential ground loop problems.

    3) With #2 in mind, how can I avoid ground loops in my own tele circuit. Are there any rules of thumb?

    Thanks for the info!
     
  2. David Collins

    David Collins Tele-Afflicted

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    1) No they can't. Not possible.

    2&3) Nothing to worry about. You could wire everything star grounded to a single point, or you could run hundreds of wires to, from, in between and around every single component in every direction possible, and it would still be completely impossible to achieve a ground loop.

    http://www.aqdi.com/groundloop.htm
     
  3. Boolywho

    Boolywho Tele-Meister

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    Is this because there is only one true connection to ground in the circuit-- the grounding lug of the jack... as opposed to multiple connections to different grounds?
     
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  5. David Collins

    David Collins Tele-Afflicted

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    More or less. Put simply, to get a ground loop you essentially need to have some level of voltage difference in the grounds of the power supply going to different components.

    Ground loops have become a common myth in guitar wiring due to a misunderstanding of how they actually work. Many people have falsely assumed that if wires are connected in parallel between different components that current will potentially "loop" through them, simply because the wire forms a physical loop. This doesn't happen though, as current does not simply move in circles because they are available to travel through - it needs a motive to go in any direction, and if there's no voltage difference, there's no motive.

    Ground loops can occur between an amp and pedals, or a mixing board and power amp if they are plugged in to different outlets, but not inside a passive guitar circuit.
     
  6. Jupiter

    Jupiter Doctor of Teleocity

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    Only one way in and one way out for a guitar--until you touch a mike stand (or bandmate). :eek:
     
  7. Wee-Lamm.Tunes

    Wee-Lamm.Tunes TDPRI Member

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    Sorry to be late in this thread, but a ground loop can occur inside a Guitar, according to:
    http://www.guitarnuts.com/wiring/shielding/shield3.php

    Jupiter does have a valid point, when you consider Mains loops, which are entirely possible when connecting different parts of your stage gear to separate supply circuits.

    However; A great number of manufacturers have been installing shielding devices, albeit it mediocre foil tape inside the pick-guard, which also tends to create a common ground between each component, switch, pot, that is touching it. Having your pots all touching this foil as well as having their shells connected through typical soldered on connections, does indeed create 2 paths for the current to travel.

    Thought it worth mentioning, even being late in the thread, and the link above is a relevant resource. :)
     
  8. sjtalon

    sjtalon Poster Extraordinaire

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    Dr.Smith:

    Oh the pain, the pain.
     
  9. Wee-Lamm.Tunes

    Wee-Lamm.Tunes TDPRI Member

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    This article does speak well on how your different pieces of equipment can interact, but it does not speak about inside any one instrument.

    Within the guitar, we have several circuits that are interconnected in a network. One important thing to remember is that there "Should be only" 1 line into and out of a circuit, active at any one time. That is, if you have your volume and tone controls all connect directly to ground and have them connected together, then each one has to potential paths to reach ground. It will choose to take the least restrictive path and if you happen to be in contact with that path, you can become that path.

    More importantly though, having 2 paths to "signal" ground, will also create an antenna effect which will not only encourage more 60Hz hum to be picked up, but also anything else that acts as a transmitter, including fm radio signals, digital watches, cell phones, and a plethora of other things than can erode the signal.

    Ground loops within your guitar wiring should be avoided both for safety reasona as well as having a clean sound.
     
  10. dsutton24

    dsutton24 Poster Extraordinaire

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    No, that's about as wrong as it can possibly be. Guitar electronics, are not active, they're passive. The frequencies, distances, and voltage levels in a guitar are all minute, and cannot form ground loops that has any significant impact on the output. Digital watches, cell phones, and the like cannot interfere with the signal from a guitar, and FM radio transmitters certainly cannot. As far as the 'antenna effect' for 60 hz noise goes, the wiring is not the culprit when 60 hz noise is a problem, but rather the mile or so of wire wrapped up in the pickups.

    That Guitarnuts article has been kicking around for a long time. It was complete hogwash then, and it hasn't improved with age. It's too bad that useful information doesn't have the staying power that nonsense does. You want a quiet guitar? Use good components, pay attention to wire dress, make sure everything is grounded properly, and most of all, learn to solder. That's all it takes.
     
  11. Bartholomew3

    Bartholomew3 Friend of Leo's

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    I bought a Les Paul Studio with "hot" pickups a couple of years back and recently noticed it picks up static electricity and makes static noise at times. It seems to depend on where I am and what I'm using for an amp plus carpet under my feet or not. The static may be building up in the control panel behind the back-plate. More expensive Les Pauls have a metal shield in the control cavity over the pots and wiring but not this Studio model - would that make a difference ?

    I expect buzz to some extent when using the coil-split but not otherwise. Also notice that touching metal on the guitar reduces the slight buzz that I sometimes get on the humbuckers.

    Now I'm pretty sure it wasn't that way last year - was completely silent so short of re-wiring a new guitar does anyone have suggestions - is shielding paint needed with humbuckers ?
     
  12. Glen Smith

    Glen Smith RIP

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    The Blacktop Tele has humbuckers and the cavities have shielding paint and the bridge has a ground wire.
     
  13. Nyles

    Nyles NEW MEMBER!

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    Hi, new to the forum. Just a quick question. I have a Stratocaster with 3 single coil pups and I have metal Telecaster type control knobs on it. The pickguard came with a foil tape on the inside. I have a ground wire running from each pot to the top of the volume pot grounded there along with the ground wires from the bridge and input jack. All of my solder points are clean but I get a horrible buzz even at lower voume/distortion. Also if I pace my hand on any metal part of the guitar ie knobs, strings, bridge, the hum stops almost completely. I have the guitar apart right now and I have copper shielding tape I will be installing tomorrow to try to fix the hum. This thread has been helpful so far, just looking to get some insight on what I should do. The top of my pots does come in direct contact with the aluminum tape that is on the back of my pickguard.
    Thanks!
     
  14. sjtalon

    sjtalon Poster Extraordinaire

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    May be be best to start a new thread.

    Welcome to the forum.
     
  15. dsutton24

    dsutton24 Poster Extraordinaire

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    If touching the metal parts on your guitar makes the noise go away, it's all grounded properly. For shielding to do any good at all, all the shields need to be bonded together and grounded to your guitar's ground system.
     
  16. Nyles

    Nyles NEW MEMBER!

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    Shielded the pickup cavity and input jack cavity. Quiet as a mouse now, no buzz even with the volume cranked. Well worth the $10 for copper shielding tape.
     
  17. telex76

    telex76 Doctor of Teleocity

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    Good deal.
     
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