#1
Hi!
According to Guitar Nuts.com (http://www.guitarnuts.com/technical/noisebucket.php)
If the hum diminishes when you are touching the strings, YOUR body is being grounded. Which previously i have always thought that our body are the ground for the string.
If so, then doesn't that mean with any properly grounded rig, the noise hum level should decrease when you touch the strings (unless of course you happen to have a wooden non-conductive body)?
If so, then how does it explain the fact that when I plug in my Blackstar HT5 into a ungrounded socket (only 2 pongs connected), if I touch the strings, the noise still decreases? According to the page, touching a ungrounded rig should make the noise louder since we human are acting as noisy antennae?

Confused as ever, people who know their electrics please help!
Regards,
Ray
#2
I believe the neutral prong of the wall socket is still connected to ground in your house's internal wiring. Therefore when you touch the strings, your body is still grounded through the neutral wire. The earth wire is just there for added safety I believe. In case the neutral wire is interrupted, the third prong (the earth wire) still provides a safe ground path for harmful voltages.
#3
We do act as an antenna, and produce electrical interference ourselves. But a rig doesn't need to be earthed to be grounded.

Earth is a direct path to physical earth carrying any surges shorts etc. there rather than through the user.

Ground is the solidly connected chain of grounding points through all your equipment and keeps the noise out of the signal chain. If your equipment is earthed the noise has a path to earth and is (in theory) removed from the equation. If it isn't earthed the grounding keeps noise away from the path where your signal gets processed (although technically your signal is a push pull between the signal chain and ground so travels along ground too but that's where the theory starts to get very complicated)

As for your comment about the neutral prong... I believe you're wrong or your electrics wouldn't work :p as wall voltage is AC both live and neutral (misnomers) swing between 0V and 110/230/240V depending on location, if one side was connected to earth all the voltage would run away :p
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#4
Quote by GABarrie
As for your comment about the neutral prong... I believe you're wrong or your electrics wouldn't work :p as wall voltage is AC both live and neutral (misnomers) swing between 0V and 110/230/240V depending on location, if one side was connected to earth all the voltage would run away :p

Pretty sure that the neutral is staked into the ground and has the same potential as earth.
Also pretty sure that AC swings negative, and the 120V/240V figures are RMS.

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#5
Ok, so there seems to be two theory?
1) Rif doesn't need to be earthed to be grounded, therefor the noise decreased when I touched my guitar while playing through a 2 pong power socket
2) The neutral side was acting as a ground?
#6
Quote by GABarrie
As for your comment about the neutral prong... I believe you're wrong or your electrics wouldn't work :p as wall voltage is AC both live and neutral (misnomers) swing between 0V and 110/230/240V depending on location, if one side was connected to earth all the voltage would run away :p

No. 110/230/240 are RMS values. In the US, the active wire actually swings between -155 and +155V, which gives you an RMS voltage of 110V.

The neutral is always taken to be zero volts (relative to the active wire). It's the common point of connection for all electrical loads in your house, therefore it's the lowest voltage that anything connected to the system can achieve. However, it's only taken to be zero volts. The absolute voltage is probably something different (in fact it's immeasurable). The earth (as in the ground you're standing on) and the neutral point are likely to be at different absolute voltages. If you come along and touch the neutral wire, there would be a potential difference between yourself and the earth and you'd get electrocuted. That is why the neutral is bonded to the earth at some point. That way the neutral connection achieves the same absolute voltage as the earth and the risk of electric shock is minimised.
#7
What you're experiencing is the idea of a "better ground." You're confusing poorly grounded with not grounded at all. If there's no ground, you don't get power. Less noise means a better ground. More noise doesn't mean no ground, it means a worse one.


Of the two prongs on a power outlet, one is neutral. It has to be. Volts are measured in a difference in potential. If one side is 120 V, the other side has to be 0 or the measured voltage in between will be wrong, since you you subtract one side from the other to determine the voltage across a device. Your two prong outlet isn't ungrounded, it's un-earthed. It still has a neutral/ground prong.

The third prong is, as mentioned before, usually an earth. That just means it provides a better ground.

When you touch the strings and the buzz decreases, it's just because you're providing a better ground for the guitar than the amp is.
#8
Quote by Roc8995

When you touch the strings and the buzz decreases, it's just because you're providing a better ground for the guitar than the amp is.


Ok sir, I was with you until the last bit, when you said that I was providing a better ground. But doesn't that contradict with Guitar Nuts' Page? (of course it can be wrong)
So in the end of the day, is guitar grounding my body's noise? Or is my body grounding the strings' noise?
#9
I don't want to say that the site is completely wrong, but it doesn't make any sense to me. If you leave a guitar all on its own on a stand, it will make a bunch of noise. If you walk up and put your fingers on it, the noise goes away (this is for, say, a properly grounded Strat with just a little hum). That website seems to claim that your body is creating the noise, which makes zero sense to me, given the results of that experiment.
#10
Quote by Roc8995
I don't want to say that the site is completely wrong, but it doesn't make any sense to me. If you leave a guitar all on its own on a stand, it will make a bunch of noise. If you walk up and put your fingers on it, the noise goes away (this is for, say, a properly grounded Strat with just a little hum). That website seems to claim that your body is creating the noise, which makes zero sense to me, given the results of that experiment.

I know, that's how I feel. But then you can do a simple test by putting on your hand on let's say the lamp or computer monitor, while just holding your guitar. (you don't need to touch the metal part). The noise should increase by a lot, but if you touch the strings while touching the monitor, the noise level will drop by a lot. I guess that that shows the strings is grounding your body? which is conductive to the noise from the monitor.
#11
Why should the noise level increase? A lamp is pretty well grounded. It's a big chunk of metal.

Grounding your body doesn't make any sense to me because if that were the case, you'd be able to hear more noise when putting your hand closer to the guitar, or when wearing rubber soled shoes, etc. None of that seems to be the case, so I can't possibly believe that you're causing all that noise that goes away when you touch the string.

Edit: Just checked with my multimeter. My lamp provides 9 mV lower ground than I do. My monitor provides .8 mV lower ground. Not much, but it seems to go contrary to the claim that they should introduce a ton of noise. Maybe RF interference, but that's not what we're talking about.
#12
I think everyone here is getting ground and earth confused. They are the exact same thing. Earth is ground. It's just different names for the same thing.

The neutral is grounded (earthed) in your house. The earth wire is there for added safety. For example, consider a microwave oven. Current flows into the microwave on the active wire, and flows out on the neutral wire at 0V. If a fault occurred and the active wire somehow came in contact with the microwave case, you'd have a serious problem as the microwave oven itself would then be at 110/230/240V. You'd come along to put your bacon in and get zapped. The third prong on the outlet (the earth wire) is connected to the metal casing of the microwave. If a fault happens and the active does touch the case, it conducts straight to earth through the earth wire. The circuit breaker in your switchboard detects the current flowing in the earth wire and trips the circuit, saving your life.

It's a bit confusing because the neutral is earthed, but then you also have a separate earth wire. The difference is that the neutral is designed to carry current into the earth always, it is the current return path for the electrical device under normal operating conditions. The earth wire is designed to never have current flowing in it - as soon as it does something bad has happened.

Quote by Roc8995
I don't want to say that the site is completely wrong, but it doesn't make any sense to me. If you leave a guitar all on its own on a stand, it will make a bunch of noise. If you walk up and put your fingers on it, the noise goes away (this is for, say, a properly grounded Strat with just a little hum). That website seems to claim that your body is creating the noise, which makes zero sense to me, given the results of that experiment.

Your body doesn't create the noise, it receives it from the surroundings and directs it straight at the guitar pickups when your nearby. Believe it or not the human body acts as a pretty good antenna for all that electromagnetic radiation that is flying around in the air (radio waves, microwaves, etc). Ever noticed that your TV reception gets better when you grab hold of the antenna? Some touch sensors actually work like this, they detect the increase in radio reception when you touch them.
#13
^ I see, so basically, when I touched my 2 pong amps (Roland Cube and Blackstar), the noise decreased because the noise my body picked up which was then picked up by the pick up was being grounded through the neutral end of the socket? Since the neutral end is already a ground, why does a 3rd separate ground make the amp a lot quieter without me touching the strings?

And why do DC powered pedals come without the third ground plug?
#14
Quote by RayL
^ I see, so basically, when I touched my 2 pong amps (Roland Cube and Blackstar), the noise decreased because the noise my body picked up which was then picked up by the pick up was being grounded through the neutral end of the socket? Since the neutral end is already a ground, why does a 3rd separate ground make the amp a lot quieter without me touching the strings?

Are you saying the amp is quieter when you're plugged into a 3-plug socket? That doesn't make much sense to me. The only thing I can think of is that the amp chassis is probably connected to the earth terminal to shunt any interference. So when you plug into a 2-plug socket the chassis is no longer earthed and the amp is no longer shielded against interference. I could be wrong, I'm just speculating here.

And why do DC powered pedals come without the third ground plug?

All those DC powered pedals are usually powered by small power adapters. Those things are usually plastic (so it wouldn't matter if there was a faulty connection, it's all safely insulated anyway). The only way you could really do something bad with them would be to short the two wires, in which case you'd probably cook the power supply before anything bad happened.



Check out that power supply. It's a lot beefier, and it's in a metal enclosure. Hence it has the standard 3-plug design.
#15
Quote by shannone27
I think everyone here is getting ground and earth confused. They are the exact same thing. Earth is ground. It's just different names for the same thing.

The neutral is grounded (earthed) in your house. The earth wire is there for added safety. For example, consider a microwave oven. Current flows into the microwave on the active wire, and flows out on the neutral wire at 0V. If a fault occurred and the active wire somehow came in contact with the microwave case, you'd have a serious problem as the microwave oven itself would then be at 110/230/240V. You'd come along to put your bacon in and get zapped. The third prong on the outlet (the earth wire) is connected to the metal casing of the microwave. If a fault happens and the active does touch the case, it conducts straight to earth through the earth wire. The circuit breaker in your switchboard detects the current flowing in the earth wire and trips the circuit, saving your life.

It's a bit confusing because the neutral is earthed, but then you also have a separate earth wire. The difference is that the neutral is designed to carry current into the earth always, it is the current return path for the electrical device under normal operating conditions. The earth wire is designed to never have current flowing in it - as soon as it does something bad has happened.


Your body doesn't create the noise, it receives it from the surroundings and directs it straight at the guitar pickups when your nearby. Believe it or not the human body acts as a pretty good antenna for all that electromagnetic radiation that is flying around in the air (radio waves, microwaves, etc). Ever noticed that your TV reception gets better when you grab hold of the antenna? Some touch sensors actually work like this, they detect the increase in radio reception when you touch them.

Grounded and earthed are slightly different things. Earthed is a proper ground, that is actually connected to physical dirt. In the earth. Ground can just be the negative lug on a battery - not earthed, but a ground reference.

I'm still not convinced that you're causing all that noise. If you were really doing it, wouldn't you notice a difference in noise when not holding the guitar? Wouldn't it get louder if you were in close proximity to a lot of people? Couldn't you make the noise go away by standing barefoot on the floor? None of these things are the case. With most exterior sources of noise, like a TV or a fluorescent light, there's a very obvious proximity effect. I have a hard time believing the same wouldn't be true for a person, if that were truly the cause of all that noise.
#16
Quote by Roc8995
Grounded and earthed are slightly different things. Earthed is a proper ground, that is actually connected to physical dirt. In the earth. Ground can just be the negative lug on a battery - not earthed, but a ground reference.

I'm still not convinced that you're causing all that noise. If you were really doing it, wouldn't you notice a difference in noise when not holding the guitar? Wouldn't it get louder if you were in close proximity to a lot of people? Couldn't you make the noise go away by standing barefoot on the floor? None of these things are the case. With most exterior sources of noise, like a TV or a fluorescent light, there's a very obvious proximity effect. I have a hard time believing the same wouldn't be true for a person, if that were truly the cause of all that noise.


Perhaps someone would be kind enough to conduct a test with a recording?
With a rig that diminished noise as soon as you touch the strings, record the noise level with a condenser mic, then set the guitar down and walk away. Keeping the recording volume consistent, to see if the noise level does drop.
#17
I really doubt it will. It certainly doesn't sound like it does from the next room. Still buzzing away.
#18
Quote by shannone27
Are you saying the amp is quieter when you're plugged into a 3-plug socket? That doesn't make much sense to me. The only thing I can think of is that the amp chassis is probably connected to the earth terminal to shunt any interference. So when you plug into a 2-plug socket the chassis is no longer earthed and the amp is no longer shielded against interference. I could be wrong, I'm just speculating here.


All those DC powered pedals are usually powered by small power adapters. Those things are usually plastic (so it wouldn't matter if there was a faulty connection, it's all safely insulated anyway). The only way you could really do something bad with them would be to short the two wires, in which case you'd probably cook the power supply before anything bad happened.



Check out that power supply. It's a lot beefier, and it's in a metal enclosure. Hence it has the standard 3-plug design.


Yes sir, the amp Blackstar HT5 is so much quiter with the ground, with a 2 hole socket, the amp would be loud until I touch the string. With 3 hole socket, the amp is close to silent without me touching anything, and if I touch the strings, the last bit of the hum goes away.