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Running a ground wire to each pot

Discussion in 'Tech-Talk' started by rafasounds, Mar 14, 2016.

  1. rafasounds

    rafasounds Senior Stratmaster

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    This is something that's made me think for quite some time.
    I love seeing pictures of vintage strats (who doesn't?). I'm curious to have a long look under the pickguard to see how it's wired, how neat it is, etc.
    I have a CIJ 62-style Stratocaster that's my pride and joy (when speaking of strats). But it has always had a quite messy wiring going on under the pickguard. It has always bugged me, because I want to see a neat, clean, organized thing, and those plastic blue wires look kind of cheap.
    Recently I bought some parts for my tele, and the kit included some nice cloth wires.


    Since my strat has always had some grounding issues (it hums much more when I'm not touching the strings), I've recently decided to go through the pain of giving it a better, more neat, cleaner wiring.

    I went looking for pictures and found this (actually I've known this page for some time):
    strat wiring clean.jpg


    As you can see, there are no wires going from pot to pot on top of them. I've seen many vintage strats wired like this, with no wires on top of each pot.

    This is how my pickguard looks like at the moment:

    my strat pickguard.jpg

    The question is: can I just remove the wires that go on top of the pots? What are some consequences it might have if I just use the ground wire from the trem claw?
     
  2. fumbler

    fumbler PhD-Stratology

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    Those old pickguards rely on the mechanical connection to the shielding (the pots bolted to the shielded pickguard) for their ground. It works but can sometimes be unreliable if surfaces oxidize or if the bolt loosens up during a gig. A soldered ground connection has absolutely no negative effect and makes your guitar more reliable so, as long as you have your iron out, I recommend you do it.

    This won't affect your hum issues, though. I see that your cavity (the burst strat in the bottom photo?) is not shielded. Shielding the body cavity in your guitar with metal foil or conductive paint might help.

    Oh, I forgot to mention: your guitar humming more when you're not touching the bridge/strings is NORMAL. The bridge/claw ground is there in order to ground YOU. You are a big bag of conductive water and you act like an antenna for all sorts of noise -- unless you're grounded via the strings (that eventually ground you through the cable sleeve to the amp.) When you let go of the strings, you start to pick up and focus noise a few inches from your SC pickups. So they hum. Shielding your guitar cavities can help.

    Just make sure that all your shielding is electrically continuous with ground; otherwise it becomes an antenna for noise just like you.
     
    Last edited: Mar 14, 2016
  3. rafasounds

    rafasounds Senior Stratmaster

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    Thanks fumbler. Yes, the bottom picture is my guitar. So, the vintage style of grounding relies on the shielding of the pickguard. I see. So, I guess I'm keeping my pots all wired between each other. I'll just replace the plastic wires with the cloth ones.
     
    Last edited: Mar 14, 2016
  4. Stratula

    Stratula Strat-O-Master

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    If I could offer a contrary view: any time you have multiple routes to ground (e.g., pots connected to grounded shielding and ground wiring pot-to-pot) you create a ground loop. Ground loops are tremendous antennas for RF and other sorts of electromagnetic transmissions. IMO, pick one means of grounding your system and go with that. I like employing the old sixties steel pickguard shields (connected to copper shielding in the control cavity). So far I've never encountered any issues with lost connectivity due to corrosion (and I live in the very humid mid-south).

    Conversely, I have used on at least one occasion a pickguard such as you show, above, with foil shielding in the control area. What I did was pull the shielding away from the pot holes (to isolate the pot shafts) and used neoprene washers to isolate the pots, themselves, then employed connecting ground wiring, pot-to-pot. Either solution produces a single route to ground.

    Again, not looking to pick a forum fight or say my opinions are the be-all-to-end-all, but give it some thought and do what seems best to you. Stock Strats have for decades come stock with the built-in ground loop and sales don't seem to have suffered ;), so maybe I make much ado about nothing. At either rate, the noise generated from a ground loop will likely be less than that produced from the single coil pickups. All part of the magic, perhaps.
     
    Dave Harmon likes this.
  5. fumbler

    fumbler PhD-Stratology

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    @Stratula Ground loops don't happen in a simple, passive guitar circuit. You're perpetuating a myth. Look at the shield on the back of a pickguard: there's about twenty holes in it (small and large), right? For the screws, pickups, switch, pots, etc. Each hole creates two "paths" to ground in the shielding, doesn't it? OH NO WHAT A DISASTER OF GROUND LOOPS! Except it doesn't cause any problems whatsoever. Ground is ground. Anything connected to ground by a good, soldered connection is grounded and will be at the same electric potential.

    Now, ground loops DO happen, but ONLY between two (or more) different pieces of POWERED equipment that are connected and one is grounded off a different circuit than the other.

     
  6. sjtalon

    sjtalon Senior Stratmaster

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    ▲ Yup, ground loops and twisting your pup leads is b.c.
     
  7. Stratula

    Stratula Strat-O-Master

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    Gee, I am sorry; I never intend to perpetuate internet / guitar message board mythology. After some consideration (and thank you for the video!), I see your point, an actual ground loop is incorrect terminology and yes, there exists quite a pervasive misuse of the term all over the interwebs. I have indeed experienced a true ground loop: I used to run a split pedal board (front of amp / effects loop) and tried at first to power both sides of the board with the same power supply. Hmmmmmmm!

    I'll offer up my incorrect nomenclature as another naive trust of internet propaganda (mythology). Would you accept the term "antenna?" Or maybe that's wrong, too.

    In my experience (albeit, obviously limited, relative others posting here), limiting (how about?) "loops of wiring connected variously to ground" (?) in guitar cavities has reduced noise coming from more than a few Stratocasters. But again, never was the noise change anywhere as great as the largest antenna-esque structure on the Strat - the single coil pickups. :)
     
  8. fumbler

    fumbler PhD-Stratology

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    No big deal @Stratula . I have LOTS of practice being wrong. :) So I always say "If that's the biggest mistake I make today then it's been a pretty good day."

    And you're right; anything conductive near the guitar can act as an antenna for noise . . . UNLESS we ground it. The only things in a guitar that you CAN'T ground are the components that carry the hot signal (the mile of pickup wire, the few inches of hookup wire, the switch contacts, guts of the pots, etc.) But we can enclose all those components in a grounded conductive cage (the shielding, the shielded cable sleeve all the way to the amp and don't forget the amp chassis - see https://en.wikipedia.org/wiki/Faraday_cage) to prevent noise from getting to them.
     
  9. s5tuart

    s5tuart My Dad used to say.... Strat-Talk Supporter

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    If ever I have to do any wiring work I normally star-earth everything back to the volume pot body, except the trem ground which I run straight to the output jack ground. I like it that way, but I don't know if it's any less noisy because of it.
     
  10. kaicho8888

    kaicho8888 Strat-Talker

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    That video showing the lifting of ground on the Line 6 amp is NOT SAFE! Should a short within the amp happens, it will go through the instrument shield, ABY box, to the grounded Taylor amp. The instrument cable shield is not sized to carry any high "short circuit current".

    Should a short happen in the Line 6 amp, the shield path melts, the current could go through your body (if your grounded, e.g. through touching the mike). All it takes is 50V, 10mA (cannot let-go level) for ventricular fibrillation ...wham...you're a dead rock star!

    If plugging the two amps in the same receptacle does not reduce the 60Hz hum, better to use DI units for the guitar unbalanced signal that can isolate the shield through isolation transformer or through electronic means.
     
  11. sumran

    sumran Fan of Leo

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    The video is a good demonstration of the problem but i agree that using a ground lift is the wrong solution. It creates a shock hazard.
     
  12. jvin248

    jvin248 Senior Stratmaster

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    If you are trying to quiet your Strat down ... get rid of the twisted pair from the jack to the control cavity and put in a two conductor shielded cable. Find an old RCA/VCR cable and snip the ends off to use. That small change cleans up more noise on more guitars than any other fix I've seen and tried. If still too much noise then a full cavity shielding is needed. I've also removed pickup covers and over-wrapped the bobbins with foil then put the covers back on. The shielded output cable helps the most though.
     
    Dr. Jimmy likes this.
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