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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    Things to consider about the different Metal Plates...

    The Gibson metal mounting plate is a very thin stamping. The Fender control plates are 2 x 3 times thicker. They both have slightly different properties because of that.

    The Fender control plates are mounted on top of the guitar, where as the Gibson control plate is mounted inside the cavity, there is an air space below the plate and the bottom of the cavity. There is an air space above the control plate and the cavity cover and some LP's even have the metal "Can" cover the goes over the top of the plate. So there is a big difference between the application of the Fender & Gibson plates right there.

    The Thin metal LP plates are thought by some to add capacitance. I have seen Billy from RS post his thoughts on this on several threads here at MLP before. Those are my thoughts as well.

    Many Humbucker equipped LP's can sound muddy, but that may also have to do the with the pots, the caps and the wiring method used like 50's or modern.

    The metal plate may add a small Tonal difference just like anything else involved and it may vary from guitar to guitar depending on the other factors I mentioned. Many people have claimed to notice a difference by just removing the plate and not changing any of the other components. YMMV

    Fender's normally have single coil pickups and they are usually plenty bright, so any capacitance added by the plate is negligible. The Tele, Mustang and Jazz Bass control plates are not buried down inside the control cavity with a cover over them. If they were they might sound and perform differently as well.

    Lining the control cavity with lot's of layers of copper foil can also add capacitance as well and may not be a good thing Tonally. Billy from RS has commented on this topic in several threads as well. Use the search function and you can find them.

    I personally don't think a little foil on the back of a Stratocaster pick guard is a bad thing, so I go with that. But I think lining the cavity with copper foil is really not necessary and never do that on any of my own guitars. Someone was asking about lining there cavity with aluminum foil in a thread, and that is where the picture of the "tin foil hats" was originally posted. I just thought that pic was rather humorous and kinda fit the topic so I posted it, no harm intended.

    Well you asked, so there are my thoughts on the metal plates and shielding. Take them for what their worth, but that is the best explanation I can give you.

    As far as the "C' ground wire, sure you can snip the part between the two Tone controls and the circuit will still function. But I prefer the vintage look, feel it ensures better grounding, and it makes the harness easy to install. All the LP's I have wired this way are extremely quiet even when the amp is set at high gain so the "ground loop" theory doesn't really seem to factor in with the "C" ground wire.

    I wired up a Gibson Guitar Friday night with the "C" ground there was no extra noise at all. It was as noise free as you can get from guitar wiring and I have a 4 foot long florescent light hanging over my bench right next to the amp. So I have many actual "Field Studies" to back up what I am saying about the grounding methods that I use and am not just going by what I read on the internet.

    peace, jonesy
     
  2. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    Your welcome. It took me a while to type all that out, but I tried to answer your specific questions the best I could. ;)
     
  3. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    No, it was 1981 Gibson Firebrand DC that belonged to a customer so I wasn't about to start snipping and re-soldering stuff inside his control cavity. He wanted it restored as close to original as possible so I built a new wiring harness for it. When I emailed him that it was finished he picked it up this morning at 8am as soon as he got back in town.

    Here is a pic of the control cavity....

    [​IMG]

    Plenty of "loopage" going on in there. "C" ground on the back of all the pots, vintage braided wired on both pu leads, vintage braided lead from switch to input grounded onto both Tone pots. Not a bit of hum or buzz though ;)
     
  4. FourT6and2

    FourT6and2 Senior Member

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    Yeah, I understand what you mean about it being like the tone knob on 9. That's what I like.

    The pots in my guitar rate in at around 250k or so. The new ones I'm getting from RS are over 500k. Which I don't like the idea of. But I do need a better sweep than what the stock pots have to offer. I'm going to give the new setup a try and go from there. If it's too bright (which I think it will be) I'll have to wire up something to reduce the effective value of the pots.

    In addition, my bridge pickup is a Duncan JB, which was designed to work with 250k pots, not 500k...

    But, that's a different issue than what this thread's about.
     
  5. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    Some interesting Reading about the flow of electrons...here is the link to the entire article if you want to check it out there is a little more.

    Conventional versus electron flow : BASIC CONCEPTS OF ELECTRICITY

    "The nice thing about standards is that there are so many of them to choose from."

    Andrew S. Tanenbaum, computer science professor

    When Benjamin Franklin made his conjecture regarding the direction of charge flow (from the smooth wax to the rough wool), he set a precedent for electrical notation that exists to this day, despite the fact that we know electrons are the constituent units of charge, and that they are displaced from the wool to the wax -- not from the wax to the wool -- when those two substances are rubbed together. This is why electrons are said to have a negative charge: because Franklin assumed electric charge moved in the opposite direction that it actually does, and so objects he called "negative" (representing a deficiency of charge) actually have a surplus of electrons.

    By the time the true direction of electron flow was discovered, the nomenclature of "positive" and "negative" had already been so well established in the scientific community that no effort was made to change it, although calling electrons "positive" would make more sense in referring to "excess" charge. You see, the terms "positive" and "negative" are human inventions, and as such have no absolute meaning beyond our own conventions of language and scientific description. Franklin could have just as easily referred to a surplus of charge as "black" and a deficiency as "white," in which case scientists would speak of electrons having a "white" charge (assuming the same incorrect conjecture of charge position between wax and wool).

    However, because we tend to associate the word "positive" with "surplus" and "negative" with "deficiency," the standard label for electron charge does seem backward. Because of this, many engineers decided to retain the old concept of electricity with "positive" referring to a surplus of charge, and label charge flow (current) accordingly. This became known as conventional flow notation:

    [​IMG]

    Others chose to designate charge flow according to the actual motion of electrons in a circuit. This form of symbology became known as electron flow notation:

    [​IMG]

    In conventional flow notation, we show the motion of charge according to the (technically incorrect) labels of + and -. This way the labels make sense, but the direction of charge flow is incorrect. In electron flow notation, we follow the actual motion of electrons in the circuit, but the + and - labels seem backward. Does it matter, really, how we designate charge flow in a circuit? Not really, so long as we're consistent in the use of our symbols. You may follow an imagined direction of current (conventional flow) or the actual (electron flow) with equal success insofar as circuit analysis is concerned. Concepts of voltage, current, resistance, continuity, and even mathematical treatments such as Ohm's Law (chapter 2) and Kirchhoff's Laws (chapter 6) remain just as valid with either style of notation.

    You will find conventional flow notation followed by most electrical engineers, and illustrated in most engineering textbooks. Electron flow is most often seen in introductory textbooks (this one included) and in the writings of professional scientists, especially solid-state physicists who are concerned with the actual motion of electrons in substances. These preferences are cultural, in the sense that certain groups of people have found it advantageous to envision electric current motion in certain ways. Being that most analyses of electric circuits do not depend on a technically accurate depiction of charge flow, the choice between conventional flow notation and electron flow notation is arbitrary . . . almost.

    Many electrical devices tolerate real currents of either direction with no difference in operation. Incandescent lamps (the type utilizing a thin metal filament that glows white-hot with sufficient current), for example, produce light with equal efficiency regardless of current direction. They even function well on alternating current (AC), where the direction changes rapidly over time. Conductors and switches operate irrespective of current direction, as well. The technical term for this irrelevance of charge flow is nonpolarization. We could say then, that incandescent lamps, switches, and wires are nonpolarized components. Conversely, any device that functions differently on currents of different direction would be called a polarized device.

    There are many such polarized devices used in electric circuits. Most of them are made of so-called semiconductor substances, and as such aren't examined in detail until the third volume of this book series. Like switches, lamps, and batteries, each of these devices is represented in a schematic diagram by a unique symbol. As one might guess, polarized device symbols typically contain an arrow within them, somewhere, to designate a preferred or exclusive direction of current. This is where the competing notations of conventional and electron flow really matter. Because engineers from long ago have settled on conventional flow as their "culture's" standard notation, and because engineers are the same people who invent electrical devices and the symbols representing them, the arrows used in these devices' symbols all point in the direction of conventional flow, not electron flow. That is to say, all of these devices' symbols have arrow marks that point against the actual flow of electrons through them.
     
  6. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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  7. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    Thanks BB :thumb:
     
  8. Raz59

    Raz59 Senior Member

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    Yep, I can testify that. In my circuit analysis classes, they teach you the means to calculate values (Ohm's Law, Kirchhoff's Laws/Methods, Thévenin's theorems). Then it's all up to you as to how you calculate what is asked, there is a plethora of ways to get to the correct answer. And unless previously marked, I can set the direction of the currents to my liking.

    As long the math is consistent with the previously marked directions, results will end up being correct. :)
     
  9. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    Ok, with that being said how do you really think the current is actually flowing in a guitar circuit - to + or + to - and how does that apply to the signal seeking a path to ground? In school I was taught in electronics & physics class that it flowed - to + so that is what I have always gone by :hmm:
     
  10. Raz59

    Raz59 Senior Member

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    Why does lightning hit trees/highest point and not the ground itself?
    If you put a piece of cheese in front of a mouse, do you think he'll take the high road or a straight path to it?

    Don't think about it too much. In terms of electronics, like I said in a deleted post (I think), the ground is a theoretical point where there is zero voltage. So the signal, that is produced in a point of higher voltage, seeks the shortest path to ground. Flow of electrons might be in reverse, but that's how things are considered in electrical engineering.

    In Physics, what you probably learned is that what is exchanged between atoms is electrons. If an atom has a deficiency of 2 electrons, it is charged positively, if it has excess, it is charged negatively.

    So electrons normally travel to positively charged atoms, to restore balance. Make any sense?

    Current travels to higher voltage (+) to lowest voltage (-). Plus and Minus is related to VOLTAGE.
    Electrons (-) are repelled by other electrons (-), attracted to protons (+) and form connections with positively charged atoms (+). Plus and Minus is related to CHARGE.
     
  11. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    OK, so then if it takes the path of least resistance then why is there such a big concern about the concept of having a "ground loop" in a guitar circuit?

    If the signal takes the easy path to ground or whichever direction you want to say that it's actually flowing then what makes you think it is going to get caught up in a loop and go round and round instead of just taking the easy path to ground? :hmm:

    You had stated in an earlier post that the signal actually travels in a straight line,(path) so the whole idea of a ground loop being a problem does not really seem correct.

    Can you yourself provide the math to show this to be true? (not copy and pasted from the internet) Enlighten me.
     
  12. onehippie

    onehippie Senior Member

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    lightning hits the trees because of energy bolts reaching out from tree tops that happens above all higher than ground objects us trees lightning rods looks like a mini bolt
     
  13. MrRhoads

    MrRhoads Senior Member

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    Raz59 have you tried any of Jonesy´s or RS Guitarworks harness´s?
    I´ve tried RS Vintage kit and some of Jonesy´s stuff and i ended up with Jonesys Jimmy Page harness with prewired toggle switch and output jack.

    --- Killer harness´s and no hum (bad grounding). ---
     
  14. Raz59

    Raz59 Senior Member

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    No, I said that the connection to GROUND can be reduced to a straight line, in terms of schematics. Just read the literature about ground loops, jonesy. It's a problem and it certainly doesn't make the guitar more silent.

    The signal takes the shortest path to ground, yes. But even some current will flow to longer paths, or paths with greater resistance; even in CAD simulations there are some leftover currents you can see, but the values are so low that it's rounded out to zero. That left over current will flow 'round and 'round the ground loop and it'll induce noise to the circuit - that's why it's bad practice.

    Did you ever see the guys over at 'The Squawk Box' saying "Hey Cygnus, my Phaez is really noisy, I'm thinkin' of adding more connections to ground"?
    Try doing what you're doing in an amp or a pedal. What you'll obtain is what is going on that Firebrand, but augmented to a level where you can hear significant noise.

    Fortunately, gadgets were invented for such an ordeal, called multimeters. I don't know if yours is sensible enough to detect, but try probing the redundant ground connections you have on the Firebird.
     
  15. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    Well first of all this thread is all about guitar wiring and grounding, not amps, pedals or any high voltage devices. We are talking some measurable current generated by the guitar pickups, but very tiny amounts.

    So if we add a "loop" into the guitar wiring which path will the signal follow? Will it continue in the same direction as the rest of the circuit, or will it somehow be able to change direction and head in the opposite direction?

    Can the signal in your guitar travel in both directions at the same time? :hmm:

    Since you yourself cannot provide the math (I really wish you could) to prove that this problem really exists, please indulge me at look at this diagram I have prepared. The Black arrows show the original direction of the way signal is traveling.

    I added another wire or "loop" if you will. The Red arrows show the opposite direction the signal would have to flow if it was going to follow the "loop" now to be honest I don't think it can do that. I think the signal will seek the path of least resistance just as water does and keep heading in the same direction.

    Can water run up hill? No, it always flows in the path of least resistance. And based on my experience from wiring guitars I find this to be true. If I have missed something here please fill me in.

    BTW My mutlimeter's work just fine.

    [​IMG]
     
  16. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    My multimeter's all work fine.
     
  17. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    BTW, I actually spent over 3 hours trying to figure out the best grounding method for my MSP rigs. Why? Because on the out the of phase mod hot and ground are reversed. And on the Series mod the + and - connections on both pu's are re-routed from a parallel to series connection.

    Same thing applies on the 21 Tone Jimmy Page rigs. If the ground path is not run correctly on that type of wiring you basically end up with a Kill Switch. Why? Because the signal takes the path of least resistance. I have spent a lot of time studying the aspects of grounding that are really important in the kind of work I do. Just wanted to pass that on to you in case anyone is going to try wiring up those type of mods.
     
  18. Raz59

    Raz59 Senior Member

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    As for the rest of the post, I'm sorry for not being able to provide you with the math like you asked. There is only so much I know and can do.

    Using water analogies for electrical systems is very valid, so let's see if I can explain myself properly:
    First, you have a mesh formed by the Battery and the lightbulb. If you add that strand of copper wire, it's creating a new mesh. You now have two meshes and you can calculate each mesh's current.

    Remember, this is from a circuit analysis standpoint of view, so you can't really be adding the path of the electrons. You should be adding the path of the current. So yes, current will be flowing through the new mesh.

    As for the "uphill" analogy, remember that "uphill" and "downhill" means higher voltage and lower voltage.

    And finally, for the example of "no resistance" VS "resistance" path ways, you can try the following: hook up a battery connected to a resistor that is in parallel to the copper wire. By your reasoning, no current should be passing through the resistor, right?

    Well, using a water analogy, imagine a running river. Now image that there's a branch in the middle of the river. Do you think that all of the water will miss the branch? It the river has less resistance, yet some water will still pass through the little branch.
     
  19. Raz59

    Raz59 Senior Member

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    And my point is that ground loops won't make buzzes or hums go away like you claim they do! If we can agree on that, I ask BB to clean this once again, please.
     
  20. jonesy

    jonesy GLOBAL WIRING GURU MLP Vendor

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    Look at the grounding method used in this Seymour Duncan diagram. Notice anything different from the traditional 50's LP wiring as far as the grounding is concerned? :hmm:

    [​IMG]






    OK I have a another question for you. Do you think that this Jimmy Page wiring as shown here in this Seymour Duncan diagram will work as shown??

    Do you see any ground wires connected the back of the pots?

    Do you think any ground wires are needed?

    Who can diagram the actual signal path and grounding for this type of 21 Tone circuit to function properly?

    Anyone?

    [​IMG]
     

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