Guitar Grounding Common Misconceptions?

jonesy

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That's interesting, because I agree in theory it should help keep things quieter, but the funny thing is, I have excessive hum on my Orville by Gibson LP, and in trying to reduce the amount of hum, I unsoldered the ground wire and the hum was dramatically reduced (though not totally eliminated).
I have heard a theory where some people bodies act as an antenna and actually add noise into the guitar. But not sure if that is really true or not. I know you act as a ground when you touch the strings.

Hum or buzz comes from bad soldering, improper grounding or a partial short somewhere in the circuit or pickups.
 

JakeDSL

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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. ;)
Working (soldering is extreme;y tedious and difficult work.) Trust me, I've tried learning from this and other forums for years now, and there is a magic and talent to it. You can't just learn how to do this. It takes many many many hours of trial and (mostly) failure as well as hands on guidance from an experienced pro. You cannot just learn to fix a guitar over the Internet. Period. There are many things that must be learned and discussed that only can arrive from a human element involved in your learning process.
 

jonesy

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Working (soldering is extreme;y tedious and difficult work.) Trust me, I've tried learning from this and other forums for years now, and there is a magic and talent to it. You can't just learn how to do this. It takes many many many hours of trial and (mostly) failure as well as hands on guidance from an experienced pro. You cannot just learn to fix a guitar over the Internet. Period. There are many things that must be learned and discussed that only can arrive from a human element involved in your learning process.
Soldering up guitar wiring and other components is not rocket science or "magic" and there is definitely some skill involved. And like anything the more you practice and spend time learning about it the better you get at it.

I have had dozens of people with minimal experience purchase harnesses and DIY kits from me an successfully installed and assembled their own wiring and pickups. True enough that some people are just not cut out for this type of thing, but many are. Sounds like maybe you have had problems and are speaking more from personal experience, but you shouldn't discourage those that are willing to try.
 

SuiteAmpCo

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I just iinstalled a new harness in my SG. I used the RS 50's wiring scheme (very clean and easy to do). I shielded the cavity 100% with copper tape with condujctive adhesive. Since this took a lot of small pieces to cover gaps I ran a braided ground sleave and soldered it to the tape inbetween the pickups and to the back of the neck vol pot. I get ground continuity like a dream anywhere on the guitar (a tuning post to a comparment cover screw). I took the ground wire from the tailpiece and used it to wrap and sorta wire tie my pickup leads (2 wire, inner wire & braided ground). That is how I found it when I opened the electronics compartment, so I gave it the same purpose when I rewired it.
So far the guitar is DEAD quiet. Even with my crappiest practice equipment its noiseless. Should I solder the tailpiece ground wire to my jack or one of the pots? Or leave it? I did notice a hum before I replaced the wiring when I lifted me hands from the strings. Is this the result of a bad tailpiece ground? Btw its a Gibson Faded Special SG (lil $700 model) with big boy electronics in it now.
 

jonesy

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The ground wire to the tail piece studs normally solders to the back of the neck volume pot in SG's. They way that ground works is, when it is connected properly any slight noise will be gone when you touch the strings. So sounds like it was connected and working fine before the re-wire.
 

guitarnut_germany

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5.) If you have a bad ground aka "buzzz" and your guitar is noisy it is most likely due to either a poor solder connection, partial short or dirty ac power.
I have buzz and hum, even when the guitar is not plugged in. When I touch the metal part of the plugged in cable jack, not the tip (cable is plugged into the amp but NOT the guitar), OR any metal part on the amp, the buzz is GONE. Does that mean I have dirty AC power??

I checked the connection from bridge to jack on the guitar with a multimeter and it sems ok. I think the guitar itself is grounded ok.

This has been really frustrating for me!

cheers
 

jonesy

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I have buzz and hum, even when the guitar is not plugged in. When I touch the metal part of the plugged in cable jack, not the tip (cable is plugged into the amp but NOT the guitar), OR any metal part on the amp, the buzz is GONE. Does that mean I have dirty AC power??

I checked the connection from bridge to jack on the guitar with a multimeter and it sems ok. I think the guitar itself is grounded ok.

This has been really frustrating for me!

cheers
Hard to say exactly but maybe pickup an outlet tester like this and see if your outlet is properly grounded. The humm could also be from another source like a computer or dimmer switch etc. Or you may have a tube going bad or faulty power transformer in your amp?


 

guitarnut_germany

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I tried my other amp at home, there was still a slight buzz, but nowhere near the buzz I had with my mesa stiletto in our practice room. It's a really old building there and I suspect the AC power might be bad there.... I'll try the stiletto at home for a comparison!
 

goldtop56

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ok so i am about to start wiring my epiphone 56gt like they did in the 50s im pretty new to wiring guitars so was hoping someone could give me a wiring diagram that is simple to follow i have got 2 PIO caps a .22 and a .15 i have got gibson braided wiring some cloth covered wire i will be using the stock pots switch and jack as i wanted to see what difference the 50s wiring had first, so hopefully someone will be able to help me
 

pmonk

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I have developed a pretty bad buzz on my 1975 Deluxe which was post-factory routed for full HB.

The original pots where replaced with 500k pots. It was fine when first done, but it was int he closet for a few months then when I plugged her in I get a horrible buzz that goes away when I (1) touch the metal casing of the guitar cord (2) touch the metal screws on the pup rings, or (3) touch any metal with my foot?

Do I need to re-do the soldering?
 

jonesy

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Maybe try spraying some contact cleaner into the pots and work them back and forth. You may have some oxidation that developed in them from sitting and that could be causing some problems.

While you have the cavity cover off also inspect for any switch or pickup wires that may be bent or touching.

It could also be a bad patch cord, dirty power supply or a faulty tube in your amp.
 

Quill

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Here is an excellent post written out by member "spitfire" in The_Sentry's thread about how he fixed his P-90 guitar. It's just a great post, and entirely germane to this important topic.

As an electrical engineer with some significant experience in keeping signals quiet, I think you done good. :applause: And, you can't argue with results.

However, it may not be shielding that fixed your problem. Though that's not wrong by any means. But much of the benefit may have come not from shielding, but from running GND up to the switch and back.

WARNING: Long technical and nerdy post coming.

Shielding, of the type in a guitar, blocks electrostatic (think capacitive coupling) and NOT magnetic interference. The shielding is simply much too thin to block 60 cycle magnetic interference. Not even close. Probably 100's or 1,000's of times too thin to block 60 cycle magnetic interference.

But blocking electrostatic interference can be useful. So I'm NOT saying shielding isn't helpful, but I think in many cases, it's not the shielding effect that is helping in a guitar, but rather the way the ground gets run as a result of adding shielding.

It sounds like your previous wiring had JUST the signal or hot leads running to the switch with no ground wires. Electrical circuits are loops. The ground part of the circuits is equally as important as the signal part especially when looking at the circuit loop. FYI, I'm not talking about ground loop.

I'll trying to make this as short as I can, but books have been written about such things. An electrical circuit is a loop. For example, the signal comes out of the pickup goes through some guitar controls to the amp, then this signal current returns from the amp through the guitar cord shield back to the guitar and eventually back to the pickup.

Now it's the physical area of this loop that is susceptible to picking up magnetic interference. Keeping this loop are as small as possible is one of the best ways to reduce magnetic interference. For example, imagine making a loop out of a piece string. If you shape this like a circle you have the maximum area you could get with the string. But if you took the loop of string and pulled it straight. You'd have what is mostly two pieces of string side by side with little or no area between them.

This is one reason some signal cables use twisted pairs of wires so that the signal and return wires are wrapped together to minimize the area between them as well as every twist tends to cancel every other twists noise.

If you don't run the ground wire up to the 3-way switch, you may create significantly more loop area since you've run the signal to the switch, but left the nearest ground back in the control cavity. Though since the signal goes up and back, twisting the signal wires together, will help reduce loop area.

You could likely get great benefit just running a ground wire up and back to the switch, even if you don't connect it to anything. Just wrap it around the signal leads. Effectively, this is what you accomplished by using the shielded cable. And probably gave you the most benefit, rather than the shielding itself.

Bottom line is ANY place you run a signal, consider running a ground wire along with it. Think of it as sort of shadowing the signal. Or at least, twist all signal wires together. This will minimize the loop area. Using shielded cable makes this very easy.

One caution, watch out for ground loops. For those not familiar, if you can pick a ground point and follow it somewhere and get back to where you started, WITHOUT retracing your path, you have a ground loop. These loops are bad for the very same reason I mention above. The loop will pickup magnetic interference. This will induce noise current in this ground loop.

You might think that if the noise current just stays in the ground, how can it affect the signal. The reason is the ground is not a perfect electrical conductor. It has some impedance (think resistance). So the ground loop currents cause small voltages to be created across different points in the ground and depending on where this is, this noise voltage may add to your guitar signal.
 

mangus

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I'm starting my harness tomorrow and I have a doubt that I hope you can help me with, can I use U grounding shape with modern wiring or only with 50's wiring? Sorry if question is completely idiot but I've never done this and I want to do the best job possible.
 

jonesy

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I'm starting my harness tomorrow and I have a doubt that I hope you can help me with, can I use U grounding shape with modern wiring or only with 50's wiring? Sorry if question is completely idiot but I've never done this and I want to do the best job possible.

Yeah no problem, you can use the U ground with either modern or 50's wiring and it will work just fine.
 

canon_lespaul

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Hi there,
I am seeking some feedback / advice.
I recently completed my first pickup and wiring change after much research on mlp forum.
I wired my guitar to 50's wiring, and the new pickups are vintage output unpotted PAF's.
Volume and tone controls for each and combined pickups work just fine.
However there is a higher level of buzz than before and in comparison to my other guitars when the hardware is untouched, however when touching the hardware the buzz is elimated to a very low level consistent with pre wiring / pickup change.
This reinforces to me that all is well with my wiring (touching hardware grounds the circuit?), and I put it down to the unpotted pickups, but it's still bugging me that maybe the bridge grounding wire connection could be a cause, but given when touching the ground wire the buzz reduces the buzz as elected, that signifies that the guitars grounding is working well????
I've read that unpotted will create more micro phonic feedback at high gain, but will they also create more buzz when idle, or have I maybe got a grounding issue?
 

Cozmik Cowboy

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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) ;)
None of my guitars have input jacks...........:cool:
 

FourT6and2

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One caution, watch out for ground loops. For those not familiar, if you can pick a ground point and follow it somewhere and get back to where you started, WITHOUT retracing your path, you have a ground loop.
Already brought up pages and pages ago. But in a guitar that uses braided 2 conductor leads, all of the pickup and switch braids are touching each other in the wire channel before they reach the control cavity. You can start on the back of the neck volume pot, for example, and follow ground from the pot casing to the neck pickup braid up to the switch or bridge pickup braids then back down to the bridge volume pot casing. Then around the ground wire to the bridge tone pot casing, to the neck tone pot casing, and back to the neck volume pot casing. Is this not a ground loop? And if so, then there are multiple ground loops in a guitar's wiring. The pickup braids, switch braids, and jack braid are all touching. And even if all the braided leads were isolated with shrink tube, the switch and jack braids are all connected by a wire wrapped and soldered around all three up by the switch. So there's another loop that you can follow back around multiple times from multiple points. Basically, every ground connection in a typical Gibson using 2 conductor braided leads is connected to every other ground connection multiple times. How is this not a ground loop?
 




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