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Unread 07-22-2010, 09:01 PM   #1 (permalink)
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Question Guitar Grounding Common Misconceptions?

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:
Grounding Predicament


Quote:
Originally Posted by jonesy View Post
Just wanted to try and clear up a few things about the metal plate and grounding wire that runs to the tailpiece studs.

1.) The metal plate was installed in LP's that used the long-shaft pots to make it easier for the factory to install the electronics, it does not really make your guitar quieter.

2.) The metal plate also grounds all the pots together, without it you will have to run a ground wire to the back of the pots.

3.) If you remove the plate you will also have to rewire the switch and input jack junction that is soldered to the center post of the metal plate.

4.) The ground wire that runs from the tail piece bushings to the pots just grounds the strings and bridge hardware and has nothing to do with whether the metal plate is installed or not.

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.

6.) The ground wire from the post to the tailpiece may quiet the buzz slightly when you rest your hand on the strings but it will not eliminate it.

Hope that helps.


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)

Last edited by jonesy; 07-24-2010 at 06:55 PM.
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Unread 07-23-2010, 06:48 AM   #2 (permalink)
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Re: Guitar Grounding Common Misconceptions?

I thought a few pics might help out...


Grounding on a vintage 50's style LP harness using solid tinned 20 awg copper wire



Braided wire grounded to the switch lug and also grounded to each other on a Switchcraft LP toggle switch



Vintage 50's style LP wiring diagram showing grounding for braided wire and ground loop to back of pots.



Gibson Studio LP with long shaft pots and the metal mounting plate acting as a ground for all 4 pots. You can also see the center post where input jack leads and hot lead from switch are connected.





Another pic of the metal plate in a Gibson LP, notice the junction of wires on the middle center post. That is where hot from switch and hot and ground from input jack are connected. If the metal plate is removed those connections have to be re-vamped. You can also see the braided wire from the pickups grounded to the back of the volume pots.
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Last edited by jonesy; 07-24-2010 at 06:56 PM.
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Unread 07-23-2010, 09:54 AM   #3 (permalink)
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Re: Guitar Grounding Common Misconceptions?

All good info, but at least in the thread I started I was talking only about the ground wire from a pot to the bridge/tailpiece/strings. When I said "grounding predicament" that's what I was talking about - grounding the circuit to the strings and therefore through the player. Since that's what was getting rid of the noise - touching any metal component that's part of the circuit, like the output jack, a pickup or the switch ring. Could it be a problem with one of the other "grounds" in the circuit or a bad solder joint? Maybe. I don't know yet.
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Unread 07-23-2010, 10:03 AM   #4 (permalink)
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Re: Guitar Grounding Common Misconceptions?

Thanks, glad you like the info. And yeah I know what you meant in your original post, but then a lot of other questions about grounding seem to arise that people were not clear of.

And true, when the strings are grounded (via the wire that runs from the tailpiece studs) that touching them will deaden some of the extra noise. But what is causing that noise to begin with? Most likely a bad ground, cold solder joint or partial short. Take care of that problem and the buzz will go away with or without the string ground.
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Unread 07-23-2010, 10:53 AM   #5 (permalink)
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Re: Guitar Grounding Common Misconceptions?

Great thread, Jonesy...it's now a sticky thread.

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Unread 07-23-2010, 11:23 AM   #6 (permalink)
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Re: Guitar Grounding Common Misconceptions?

Quote:
Originally Posted by jonesy View Post
Thanks, glad you like the info. And yeah I know what you meant in your original post, but then a lot of other questions about grounding seem to arise that people were not clear of.

And true, when the strings are grounded (via the wire that runs from the tailpiece studs) that touching them will deaden some of the extra noise. But what is causing that noise to begin with? Most likely a bad ground, cold solder joint or partial short. Take care of that problem and the buzz will go away with or without the string ground.
Yep, hopefully I'll get it sorted.
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Unread 07-23-2010, 11:40 AM   #7 (permalink)
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Re: Guitar Grounding Common Misconceptions?

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Originally Posted by b-squared View Post
Great thread, Jonesy...it's now a sticky thread.

BB
Thanks BB, that's cool
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Unread 07-23-2010, 12:57 PM   #8 (permalink)
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Re: Guitar Grounding Common Misconceptions?

Great to see a grounding thread
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Unread 07-23-2010, 02:33 PM   #9 (permalink)
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Re: Guitar Grounding Common Misconceptions?

Here is Billy from RS Guitar works demo on how to do it.



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Unread 07-23-2010, 03:36 PM   #10 (permalink)
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Re: Guitar Grounding Common Misconceptions?

Billy does a nice job for sure. Good soldering skills and proper assembly work will make the difference between a noisy rig that buzz's to a quiet one that really sounds great
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Unread 07-23-2010, 06:15 PM   #11 (permalink)
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Re: Guitar Grounding Common Misconceptions?

Quote:
Originally Posted by jonesy View Post
Billy does a nice job for sure. Good soldering skills and proper assembly work will make the difference between a noisy rig that buzz's to a quiet one that really sounds great
Well, I sure as hell am not bringing my guitar back to the tech who put the pickup in, that's for sure. I found a new guy. He's a roadie/tech for Metallica. So, hopefully he does good work.
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Unread 07-23-2010, 06:49 PM   #12 (permalink)
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Re: Guitar Grounding Common Misconceptions?

Quote:
Originally Posted by FourT6and2 View Post
Well, I sure as hell am not bringing my guitar back to the tech who put the pickup in, that's for sure. I found a new guy. He's a roadie/tech for Metallica. So, hopefully he does good work.

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.
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Unread 07-23-2010, 07:33 PM   #13 (permalink)
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Re: Guitar Grounding Common Misconceptions?

Great thread Jonesy, I learned a lot!
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Unread 07-23-2010, 07:43 PM   #14 (permalink)
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Re: Guitar Grounding Common Misconceptions?

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Originally Posted by brianugly View Post
Great thread Jonesy, I learned a lot!
Thanks Brian, glad to hear that.
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Unread 07-23-2010, 09:44 PM   #15 (permalink)
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Re: Guitar Grounding Common Misconceptions?

Ground loop (electricity) - Wikipedia, the free encyclopedia

"In an electrical system, a ground loop usually refers to a current, generally unwanted, in a conductor connecting two points that are supposed to be at the same potential, often ground, but are actually at different potentials. Ground loops created by improperly designed or improperly installed equipment are a major cause of noise and interference in audio and video systems. They can also create an electric shock hazard, since ostensibly "grounded" parts of the equipment, which are often accessible to users, are not at ground potential."

Now jonesy, I understand when you say "ground loop", you're referring to the shape of the solid bus wire.
Non the less, in terms of semantics you're using an ambiguous thing, and it may lead to confusion (this applies to other terms such as "full sized" pot and "braided 2-lead").

Further, if you look at how in the olden days people soldered the toggleswitch on a Les Paul:



The middle braid shield comes from the jack, which means that is the actual ground and the one you put a PVC cover on in the control cavity (to avoid grounding then what's wanted). If you solder all 3 braids together, then all 3 braids become a path to ground.

Which means that, in these pictures:




The bus wire from Bridge Tone to Neck Tone is completely unnecessary. Now THAT is a true ground loop, it's an extra connection to ground...and both of the pots are already grounded by the wires coming from each volume pot.

The AC current produced by strumming the strings on an electric guitar is very small, but still, is it a good idea to be telling people to wire a ground loop?
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Unread 07-23-2010, 10:45 PM   #16 (permalink)
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Re: Guitar Grounding Common Misconceptions?

Raz, what's interesting is some RS kits come with that "ground loop" wire connecting all the pots and some come with out it (bridge volume/tone connected and neck volume/tone connected, but bridge not connected to neck).

I think it depends on how you wire the rest of the guitar. For example, my guitar (stock) has a metal ring in the switch cavity that the switch gets grounded to. There is no ground wire wrapped around all three leads.
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Unread 07-23-2010, 11:04 PM   #17 (permalink)
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Re: Guitar Grounding Common Misconceptions?

Quote:
Originally Posted by Raz59 View Post
Now jonesy, I understand when you say "ground loop", you're referring to the shape of the solid bus wire.
Non the less, in terms of semantics you're using an ambiguous thing, and it may lead to confusion (this applies to other terms such as "full sized" pot and "braided 2-lead").

Further, if you look at how in the olden days people soldered the toggleswitch on a Les Paul:


The middle braid shield comes from the jack, which means that is the actual ground and the one you put a PVC cover on in the control cavity (to avoid grounding then what's wanted). If you solder all 3 braids together, then all 3 braids become a path to ground.

Which means that, in these pictures:
<snip>

The bus wire from Bridge Tone to Neck Tone is completely unnecessary. Now THAT is a true ground loop, it's an extra connection to ground...and both of the pots are already grounded by the wires coming from each volume pot.

The AC current produced by strumming the strings on an electric guitar is very small, but still, is it a good idea to be telling people to wire a ground loop?





The main reason that all 3 braided leads from the switch are soldered/grounded together in the 50's wiring is that's is how the ground from the back of the pots is routed to the input jack through the braided lead.

Without that connection there at the switch there would be no ground going to the input jack. The ground from the switch lug is just a "hardware ground" the input jack has to be grounded to the "circuit" so the braided provides the "ground" to complete that.

The modern wiring has the the input jack lead run to the center post ground or just soldered right to the back of one of the pots. The 50's wiring has the ground run from the pots to the switch then to the input jack. Hope that clears things up.




And you also have to consider that many times the switches in many LP's have the color coded PVC wire so the ground path is not the same as with the 50's style braided wire to the switch so the "ground wire" on the back of the pots is necessary. Do you follow me?

Last edited by jonesy; 07-24-2010 at 07:20 PM.
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Unread 07-23-2010, 11:28 PM   #18 (permalink)
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Re: Guitar Grounding Common Misconceptions?

You can see in this pic of one of my 21 Tone Jimmy Page rigs that the ground to the input jack comes right off the back of one of the pots. This connects it into the "circuit". Then the hot to the input jack is supplied by the red wire from the switch.

The green wire from the switch is connected to the ground lug on the switch providing the "hardware" ground and it solders to the back of the bridge volume providing an additional grounding point.

The black and white wires from the switch connect to the hot lug on each volume pot. Black goes to the bridge volume and the white wire goes to the neck volume.

Depends on what variation of wiring you are using as to how the ground is routed to the input jack. As long as it get's there that's what is important



Last edited by jonesy; 07-24-2010 at 07:18 PM.
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Unread 07-23-2010, 11:31 PM   #19 (permalink)
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Re: Guitar Grounding Common Misconceptions?

So when you say "ground loop", you're describing the path of the wire to ground? Is that it?
Do you see why using this term so freely causes confusion? Now you have 3 possible meanings and only one of them is an electrical term and denotes an error!

I understand how this old styled wiring works. And the fundamental part of it is that the braided metal that is outside of the conductor wires is supposed to be a path to ground.
The purpose of the braid is to act as a shield to outside interferences.
Seeing as the braid is a path to ground and that an electric current chooses the shortest path to ground, the braid should not come in contact with any other wire, or it'll cause a short circuit.

You describe the path to ground as "ground loop", ok.



By removing the piece of wire between BT and NT, you have this shape. Do you call this a "ground trident"?
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Unread 07-23-2010, 11:37 PM   #20 (permalink)
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Re: Guitar Grounding Common Misconceptions?

The metal mounting plate is actually a "grounding point" as well


Last edited by jonesy; 07-24-2010 at 06:59 PM.
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Unread 07-23-2010, 11:50 PM   #21 (permalink)
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Re: Guitar Grounding Common Misconceptions?

The whole metal plate is in itself a ground connection...I don't understand why Gibson opted to do that, it's a really poor design.
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Unread 07-23-2010, 11:53 PM   #22 (permalink)
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Re: Guitar Grounding Common Misconceptions?

The vintage 50's circuit is also grounded all the way around as you can see here.


Last edited by jonesy; 07-24-2010 at 07:04 PM.
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Unread 07-23-2010, 11:56 PM   #23 (permalink)
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Re: Guitar Grounding Common Misconceptions?

Quote:
Originally Posted by Raz59 View Post
The whole metal plate is in itself a ground connection...I don't understand why Gibson opted to do that, it's a really poor design.
They quit using them as far as I know and switched over to mounting the controls in PCB boards in some of the current LP models .
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Unread 07-24-2010, 12:24 AM   #24 (permalink)
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Re: Guitar Grounding Common Misconceptions?

I gotta get some sleep now TTYL
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Unread 07-24-2010, 07:19 AM   #25 (permalink)
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Re: Guitar Grounding Common Misconceptions?

I put the ground wire from neck tone to bridge tone in usually just to keep the whole harness together, so it is a direct drop in, and the customer isn't left with two separate parts - avoiding confusion of which to put where.
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Unread 07-24-2010, 07:21 AM   #26 (permalink)
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Re: Guitar Grounding Common Misconceptions?

Quote:
Originally Posted by Raz59 View Post
Yes jonesy! That is a true ground loop, ground loops are bad! I mentioned that in my first post!

So you should be wiring it like this:

http://img80.imageshack.us/img80/215...428a90208f.jpg

Do you call this a "Ground Trident"? Because, as you can see, the central ground connection is where all 3 braids are soldered (near the switch cavity), which makes the BT to NT connection completely redundant.
What about the point where all three braided leads from the switch come into contact with the braided leads from the pickups in the routing channel? Isn't that a bad thing as well? Shouldn't they be isolated from each other? Or does that not matter?
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Unread 07-24-2010, 07:24 AM   #27 (permalink)
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Re: Guitar Grounding Common Misconceptions?

Quote:
Originally Posted by FourT6and2 View Post
What about the point where all three braided leads from the switch come into contact with the braided leads from the pickups in the routing channel? Isn't that a bad thing as well? Shouldn't they be isolated from each other? Or does that not matter?
It doesn't matter at all, as the braided wires (from the pickup and from the switch) are still being grounded. It would only pose a problem if there was a live wire touching the braided grounds - which could cause a short, or cause the guitar to work intermittently.

Basically, if a ground touches a ground anywhere in the circuit it won't matter, since they'll just be grounding to each other.
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Unread 07-24-2010, 07:48 AM   #28 (permalink)
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Re: Guitar Grounding Common Misconceptions?

Quote:
Originally Posted by FourT6and2 View Post
What about the point where all three braided leads from the switch come into contact with the braided leads from the pickups in the routing channel? Isn't that a bad thing as well? Shouldn't they be isolated from each other? Or does that not matter?
The braids from the switch are connected to ground, so any signal passing through won't pass through the amp's circuitry - it won't be amplified. So it's a shield against outside interference (I think I already said it, but it's good to know this by heart).

The braids from the pickups are soldered next to the braids of the switch purely because of aesthetics. The second you solder that braid from the switch to the back of the pot, the pot itself becomes a ground point.
Aside from the 'hot' lugs of the pickup and switch, you can solder the braids any where on the potentiometer and you'll still get an effective ground connection.

Ideally, every every element that is supposed to be connected to ground should be connected to it only in one point - not several. In a guitar, the current generated by the pickups is low, but in other high voltage situations, a circuit with ground loops can lead to unexpected/fatal situations.

It's vintage correct to just make a loopy loop of solid wire and solder it all around the pots, but it's a bad practice electrical-wise.
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Unread 07-24-2010, 08:19 AM   #29 (permalink)
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Wink Re: Guitar Grounding Common Misconceptions?

Grounding & Fender Metal Control Plates

It has been common practice since the mid 1940's for companies like Fender to use Metal Control Plates to mount the guitar electronics on. It makes them handy to load into the guitar, provides a Universal "Grounding point" and is also part of the guitar design and gives Tele's, Mustang and Jazz Bass guitars a cool look. Things have remained the same for over 60 years, here are some examples.


Fender Mustang Control Plate



Fender Jazz Bass Control Plate



Fender Telecaster Control Plate


All these Control Plates were not only designed to mount the controls on, but also to provide a Universal grounding method for the volume and tone pots. The notion that the wiring controls should only be grounded at "One Point Only" is pure nonsense. On all my Tele and Jazz Bass rigs I also solder an additional ground wire between the pots to ensure good grounding, so along with the plate the volume and Tone pots have a solid connection as well. Grounding is a good thing and helps reduce noise and provides a clear signal path.



The switch frame is grounded to the control plate, but all the + positive contacts are isolated from the plate and they handle the hot + signal from the pu's and route it into the volume pot, then on to the input jack.



Good grounding does several things...

1. It creates a ground path for the neg. - signal for your volume and tone pots so they work properly.

2. The hardware is grounded so your switch frame, bridge and strings are all properly grounded which helps reduce noise.

3. Good grounding also helps get rid of static and additional unwanted signal as it is also sent to ground via the ground loop.

GROUNDING = GOOD

Last edited by jonesy; 07-24-2010 at 07:03 PM.
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Unread 07-24-2010, 08:20 AM   #30 (permalink)
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Re: Guitar Grounding Common Misconceptions?

Quote:
Originally Posted by lukemacauley View Post
Basically, if a ground touches a ground anywhere in the circuit it won't matter, since they'll just be grounding to each other.
If a ground connection touches another ground connection at a considerable distance, you get a ground loop.

"What is ground loop ?

A ground loop occurs when there is more than one ground connection path between two pieces of equipment. The duplicate ground paths form the equivalent of a loop antenna which very efficiently picks up interference currents. Lead resistance transforms these currents into voltage fluctuations. As a consequence of ground-loop induced voltages, the ground reference in the system is no longer a stable potential, so signals ride on the noise. The noise becomes part of the program signal."


Ground loop basics
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Last edited by Raz59; 07-24-2010 at 08:23 AM. Reason: distance
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