Guitar Grounding Common Misconceptions?

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

  1. skateboardnorth

    skateboardnorth Junior Member

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  2. sidious911

    sidious911 Senior Member

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    So I've been reading through the pages here, and seems like a lot of people are trying to saying grounding loops are a real issue in guitars, and Jonesy is saying it is not. I have read in many other places that the Ground loop in a guitar cavity is a myth, and is only more of an issue when we are talking about amps and pedals.

    In my guitar build I am working on (first one) I have a Fernandes Sustainer and a MIDI control circuit in the guitar. Both are known to add some noise, so I am going to Copper Shield all my cavities.

    Some resources I have found told me not do ground the back of the pots because the Copper Shielding will do this for you, and if you do, you will create a grounding loop.

    Other resources suggest that the grounding loop is a myth in a guitar cavity, and say that you CAN but don't HAVE TO ground the pots because the shield will perform this function, but you can if you'd like to have a more secure reliable ground between pots.

    Can someone chime in here, am I safe to ground the pots together as well to have a solid connection or am I going to create a problem for myself by doing so?

    Cheers!
     
  3. Sailor Juan

    Sailor Juan Junior Member

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    Another cause of annoying noise is bad sheilding. I had this problem in my 1994 LP Studio. Some rewiring was done and I put in new pots. Along the way the wires to the switch became untwisted. There is no sheield on these wires. It took me a while to figure out after correcting and going to '50s style I then got all the wires twisted about 1 turn every couple of inches.. If anyone know the correct twist rate let me know. Hum is gone now though.
     
  4. foxtrot

    foxtrot Senior Member

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    I thought I'd follow up with this since there's a current thread on this in Gibson Les Pauls (and often many others on this issue) and would like some thoughts on the following.

    My understanding is that you do not act as a ground, but that the guitar grounds you when touching the strings (or other metal parts). Instead, your body actually acts as an antenna, picking up and strengthening ambient interference, which is then picked up by your guitar, nestled up against yourself.

    Think back decades when you had to adjust TV antennas for proper reception. Often times just touching the antenna alone would improve reception. The same sort of effect happens with actual radios when changing stations. Often, when you remove your fingers from the dial, you find the signal fades a bit and have to adjust it ever so slightly to hit the sweet spot (so that the signal doesn't fall off when you remove your fingers). This also works with garage door openers/remote door locks, holding the opener or remote key to your head to increase range, for example.

    Both of my Les Pauls hum a bit. They did brand new, and they both still do after rewiring them (one of them twice, the second time due to a pickup swap and removing coil splitting). When I touch the strings, the hum/buzz ceases.

    However, that's not all. When I allow the guitar to hum/buzz and touch another ground source (I did it with the computer end of my laptop charger), the sound also ceases in the exact same way. Touching the (painted) screws on the wall outlet lessens the hum/buzz (it also ceases if I touch my pedal switches or cables attaching the pedals).

    Again, back to my understanding, my body is picking up/amplifying some sort of ambient interference, which is grounded when I touch the metal of my guitar or another potential ground.

    In my own case, I know the cause of this interference: a lamp (that has its own dimmer) in my office with my guitars/amps. If I turn the light off, it's the same as if I touch the strings: it disappears).

    So, does this make sense? Does "human body" = antenna or does "human body" = ground?
     
  5. foxtrot

    foxtrot Senior Member

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    And thinking about this more over the last few minutes, I wonder if grounding yourself (to your guitar or any other ground) while holding your guitar makes more of a difference in that it turns your body into a big shield for your guitar, mattering more than your body's potential to act as an antenna.

    This seems to make sense, since the antenna effect itself is usually most significant through direct contact with whatever is causing the interference, or with whatever you are trying to boost the signal with by touching it to use your body as an antenna (for instance, if I touch the light that causes my hum/buzz, the noise increases quite a bit. By that same token, if you touch a TV antenna, you increase reception) :hmm:.
     
  6. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    I'd say your body acts like a ground or "load" not an antenna. When you touch the strings noise quiets down, it doesn't get louder.

    If I set my multimeter to capacitance and hold a lead in each hand and measure the capacitance through my body (dampen finger tips with sponge) I get an .015 uf reading which is fairly large size capacitor.

    The human body is made up of mostly water and electrolytes, so it is in essence a capacitor/battery. Many living organic things have these properties, I used a potato to demonstrate this as well.



    [ame=http://www.youtube.com/watch?v=huFRrcaF6VY&list=UUO93bCBpqlDLKj6GMadKwgA]"Spud-Tone" Potato Capacitor in my Telecaster by jonesyblues - YouTube[/ame]
     
  7. foxtrot

    foxtrot Senior Member

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    I think the human body acts as much more of an antenna and/or capacitor than a ground.

    If I plug a cable into my amp, leaving the other end unplugged, and touch the tip with my interference causing light turn on, I generate way more noise than with the light turned off (and touching the tip alone shows that people aren't grounding the guitars). There's also the evidence from TV antennas and radios I mentioned.

    Someone posted this in the other thread. Basically what I'm saying and sums it up pretty well. http://www.guitarnuts.com/technical/noisebucket.php

    Human seems to = antenna/capacitor. Human touching a ground = shield. Human ≠ ground for the guitar.
     
  8. foxtrot

    foxtrot Senior Member

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    These resources belong in here in the event they might help others.

    YouTube video of an ungrounded guitar. A little hard to hear so turn up your volume a lot. Notice that touching the strings (or other metal parts) on a guitar with a bad ground does not cause noise to stop, it actually intensifies the noise. Guitars ground the person, people do not ground their guitars. Also note how the pickup sounds when he disconnects the ground.

    [ame=http://www.youtube.com/watch?v=YSxXra9UN-0]Guitar Ground: Dealing with ground noise problems - YouTube[/ame]

    And here is an article from Premier Guitar on noise issues, courtesy of jab996 in another thread. It discusses a range of noise issues and solutions:

    http://www.premierguitar.com/articles/Silence_is_Golden
     
  9. camini

    camini Member

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    Hello all,

    I start by apologizing that I only read the first and last page of the thread, not the ones in between, so the answer may be there..

    On my 95 LP Standard, when plugging on what I think is a poorly grounded plug in our rehearsal room, I get quite a lot of static noise, until I touch the pickups..
    Touching the strings, tailpiece etc does not create any effect.

    My conclusion is that strings and tailpiece etc are not grounded, at least not on the same circuit as the pickups etc.

    Is this an issue? I think I've read in another thread that some LPs did not have their strings grounded, for safety reasons maybe..

    Apart from making sure I plug in in a reliable power socket, should I think about changing the grounding and adding the strings in the loop?

    All help on this is welcomed.

    Thanks!
    P-M
     
  10. Zakum

    Zakum Junior Member

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    Hi guys, the pictures aren't loading for me. Anyone else having this issue (Page 1 pictures for example).
     
  11. Lampens

    Lampens Senior Member

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    Si I had this thread going in the backstage about the grounding in my house. That part is sorted but I got on that trip because my tele showed the ground problem whereas my strat didn't.
    This thread ground problem new home. Some unusual stuff in my house.

    I decided to A/B all my guitars to see what's up and maybe if the strat wasn't grounded properly or maybe the best of them all. But I ended up more confused.

    Anyway.
    Why wasn't my strat making any ground noise? I only noticed the ground thing when I grabbed my baja tele that showcased the grounding issue with the ungrounded wall socket.
    So I checked ground on all my guitars. Some weird stuff going on.
    Going by the principle that a guitar has bad ground when you touch it it starts making noise, not quit making noise, which means good ground.
    They all seem to be grounded like they should. On all guitars the noise goes away when I touch the bridge or the pots or switches, on some the pickup covers or pole pieces too.

    Anyway, the strat doesn't make any ground noise on grounded wallsockets and only the faintest bit of hum that goes away when I touch it on an ungrounded socket. The thing is dead quiet compared to the tele that started me off on this.
    The tele is noisy as all hell as far as ground hum goes, the 6120 is almost as noisy as the tele. They are brighter sounding guitars too so that might explain it a bit too. The lp ('89 standard) is the darkest sounding.
    the lp is quiet, only a faint bit of ground hum on the grounded wallsocket, a little more on an ungrounded.
    my hamer p90 dc junior is about as quiet as the lp even though it has a p90.

    So what's the deal? How come that strat doesn't seem to have any ground issues at all? The only thing I did to it was put in bare knuckle irish tours. Maybe I've wired them differently then regular strat wiring. I've heard of strats and tele's having ground loop problems factory wired. Would that explain the excessive noise on the tele on a grounded wallsocket? I've put in tv jones in the gretsch but left the wiring as it was. '93 japan 6120. It's just as noisy as the tele as far as ground hum goes when untouched on a grounded socket.

    Another thing that puzzled me. I've checked all the guitars with a multimeter for continuity as far as grounding goes. The pole pieces on the strat and tele arent't grounded I've noticed. On the hamer and the humbucking(filtertron) guitars they are.

    Another weird thing. I really don't understand what's going on here. On the lp it doesn't give continuity between the bridge and ground on the input jack. But when I touch it it does something because the ground noise goes away and trying it with a multimeter amplified you can hear through the amp something is connecting with both leads on like say the jack and the bridge.
    Also I noticed the ground hum noise changes when the volume is fully up on the guitar, just hair back and it is different for the rest of the travel. But that could be just the way it's wired. The lp has a 50's wiring rs kit in it. (Put in by a tech but reading through this thread I see myself posting about it. So I think the tech put in the wiring harness originally and I later added 57 classics with braided wiring, I guess that's what got me posting in this thread but it looks like some posts are missing and I can't recall what problem I encountered putting in the 57's)
    But I wonder why the multimeter isn't giving coninuity between the bridge and the rest of the electronics. There should still be the factory wire from the tailpiece stud attached to the circuit and there is connectivity as evidenced by the touching-noise goes away thing.

    So a long story and I understand if nobody understands me. I don't understand me :hmm:
    I really don't know what's up with all this ground weirdness.
     

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