60Hz hum in my Les Paul

[Haze13]

Had same problem in my Epi Les Paul... Copper tape inside Control Cavity and don't forget the cover. You can use shielded wires (like mogami) for wiring your switch too.
OR you can use Active Pickups. I had one guitar with Seymours and other with EMG's. The first had that noise, but the LTD with EMG's was humm-free. Tried this at guitar store and the result was the same. Gibson USA made had this humm, but cheap LTD with EMG's was silent.

[Buzz]

If you decide to shield the cavity with copper tape make sure the tape you buy has conductive glue.

This way the tape becomes part of the shield by the simple process of overlapping the edges a bit.

Other copper tapes may require soldering at their joints.

[Haze13]

Use DMM to check the continuity.

[anotherjim]

Yes, you have to prove continuity with a meter.

That hum goes away when you touch the guitars metalwork does not prove that the guitar is properly grounded. If it was grounded, then touching it would make no difference.

However, the guitar, even with good wiring, is only grounded via whatever it's plugged into. Somewhere along the line it depends on the AC supply Earth bonding being good. Screw terminations in wall sockets can work loose. The modern practice of of building AC sockets with bits of copper and brass spot-welded together is prone to failure. Some buildings use the copper water pipes for the AC earth which may not be effective - it should be a copper spike in the ground.

That it's the same with the computer points to an AC wiring issue (you can get test plugs for your AC sockets), however it depends on the computer. They don't all have an AC grounded chassis - but a conventional desktop machine should do.

It can help (good practice in general), if you use one wall socket for your audio gear with a multiway power strip. That helps reduce hum as they all have equal access to the same ground.

[Dimitree]

Yes, you have to prove continuity with a meter.

there's  more or less 30ohm between bridge and jack ground.

However, the guitar, even with good wiring, is only grounded via whatever it's plugged into. Somewhere along the line it depends on the AC supply Earth bonding being good.

I live in Italy, and I know for sure that the majority of houses built before '70s doesn't have a proper earth connection (it is indeed illegal now). My house could be one of those. I will ask a technical to come and check the earth connection.

[GibsonGM]

Do you have an outlet tester?  VERY useful for safety, and for problems like this.   Plugging one item into one outlet, and another item into a different outlet that is wired wrong, can have VERY bad results!   That is why I thought of a problem with your power supply.



30 ohms is "a lot" for a ground, altho not in the 'super high value' range....makes me wonder why it's that high, tho.  Should just be a piece of wire a few inches long, and read almost zero ohms.    A place to look at, could be something wrong with the connection (dirty or something).   22 ga. wire has a resistance of .016 ohms per foot....personally I'd explore that "issue" and correct it.  

Could something be wired out of phase, and you're reading thru a pickup?  Hard sayin', not knowin'  

[GGBB]

That hum goes away when you touch the guitars metalwork does not prove that the guitar is properly grounded. If it was grounded, then touching it would make no difference.

This statement is absolutely false (sorry Jim).

Case in point: Take a perfectly fine well shielded coaxial guitar cable, plug it in to an amp that for the sake of this argument is properly grounded, leave the other end unconnected and turn the amp on.  Now touch the unconnected tip with your finger.  Does it hum?  You bet it does.  Now, remove your finger from the tip and touch it to the sleeve.  Does it hum?  No (well it might a little depending on the cable etc. but it won't be anywhere near as loud).  Now, remove your finger from the sleeve and bring it close to but not touching the tip.  Move it away a bit then closer again, back and forth, slowly.  Do you hear the hum level going up and down?  That is due to capacitive coupling.  No ground problems at all.  The mains wiring induces a voltage in your body which is fed into the amp through the cable via the capacitive coupling of your body to the connector tip.

It may not be your body that is the (only) source of hum, but it most surely is shielding that will reduce it as much as possible.

[Dimitree]

ok, let's say that the 60Hz hum that I hear is a 60Hz E.M. signal,
if I hear it so loud, should I care about my healt? how is possible that such strong 60Hz signal is in the air in every part of the house..

[pappasmurfsharem]

You could also do what I do when playing live.

I attach an alligator clip to the bridge and have the other end tucked in my pants against the skin.

[ashcat_lt]

Every once in a while you hear on the news (at least we used to here in amerika) about farmers complaining about how high tension power lines near their fields are endangering the health of their cattle, so yes, I think you should buy a tinfoil suit so you don't end up broiled from the inside.  Don't forget the hat!  

But actually it's not anywhere near enough to really hurt you.  It sounds loud because you're amplifying it a lot.  

And yes, a radio which is properly grounded will still work.

[GGBB]

how is possible that such strong 60Hz signal is in the air in every part of the house..

Physics.

[Johan]

Les Pauls hum when you don't touch the strings or any metal parts on the instrument. .. unless you play with gloves on or only strum open strings,  it shouldn't be a problem..i don't see how you can make music without touching the strings. ..

[anotherjim]

That hum goes away when you touch the guitars metalwork does not prove that the guitar is properly grounded. If it was grounded, then touching it would make no difference.

This statement is absolutely false (sorry Jim).

Case in point: Take a perfectly fine well shielded coaxial guitar cable, plug it in to an amp that for the sake of this argument is properly grounded, leave the other end unconnected and turn the amp on.  Now touch the unconnected tip with your finger.  Does it hum?  You bet it does.  Now, remove your finger from the tip and touch it to the sleeve.  Does it hum?  No (well it might a little depending on the cable etc. but it won't be anywhere near as loud).  Now, remove your finger from the sleeve and bring it close to but not touching the tip.  Move it away a bit then closer again, back and forth, slowly.  Do you hear the hum level going up and down?  That is due to capacitive coupling.  No ground problems at all.  The mains wiring induces a voltage in your body which is fed into the amp through the cable via the capacitive coupling of your body to the connector tip.

It may not be your body that is the (only) source of hum, but it most surely is shielding that will reduce it as much as possible.

I think you've misunderstood my point.
I'm sure the original matter was that the noise stops when the bridge is touched?
If the noise stops when you touch it - your body simply has to be making a better ground than the amp is providing! The noise is from some form of electrical interference. If touching it stops it then you are shorting it out.
Or to put it another way, I'm not saying the bridge isn't connected to the guitar jack ( but I'd still want to test that)- I mean it isn't properly grounded by the amp. Therefore the bridge is still not effectively grounded.
A very long cable, high gain amp and high impedance pickups can cause the same effect even when the amp ground is good.
A bridge not grounded to the jack with a good amp ground can be the opposite effect - it's noisy when you do touch it. You can't be the better ground in that case.

[wavley]

That hum goes away when you touch the guitars metalwork does not prove that the guitar is properly grounded. If it was grounded, then touching it would make no difference.

This statement is absolutely false (sorry Jim).

Case in point: Take a perfectly fine well shielded coaxial guitar cable, plug it in to an amp that for the sake of this argument is properly grounded, leave the other end unconnected and turn the amp on.  Now touch the unconnected tip with your finger.  Does it hum?  You bet it does.  Now, remove your finger from the tip and touch it to the sleeve.  Does it hum?  No (well it might a little depending on the cable etc. but it won't be anywhere near as loud).  Now, remove your finger from the sleeve and bring it close to but not touching the tip.  Move it away a bit then closer again, back and forth, slowly.  Do you hear the hum level going up and down?  That is due to capacitive coupling.  No ground problems at all.  The mains wiring induces a voltage in your body which is fed into the amp through the cable via the capacitive coupling of your body to the connector tip.

It may not be your body that is the (only) source of hum, but it most surely is shielding that will reduce it as much as possible.

I think you've misunderstood my point.
I'm sure original question was that the noise stops when the bridge is touched?
If the noise stops when you touch it - your body simply has to be making a better ground than the amp is providing!

If the buzz goes away when you touch the strings then there is obviously an electrical connection to ground otherwise touching the strings would do nothing.

When you touch the strings and the buzz goes away it's because your body is becoming an RF choke, just like one of these



It's a trick we use in the lab on bias wire to see if noise spikes are RFI induced in the bias wires leading to a cryogenic dewar, wrap them around your hand and if it goes away then it's interference, if it doesn't... there are other problems.

[Mike Burgundy]

Might have missed it, but *is your computer plugged into a properly grounded outlet?* The tester mentioned is always a good idea. If the (I'm assuming desktop) computer *is* plugged ito a grounded outlet, does plugging an amp into that socket yield hum?
I'm selling quite a few of these focusrite interfaces, without problems.

[anotherjim]

30 ohm is a lot for the bridge ground.
In a LP - isn't the wire pushed inside the bridge pillar hole and trapped by the ferrule?

[GGBB]

I think you've misunderstood my point.

I'm sure the original matter was that the noise stops when the bridge is touched?

If the noise stops when you touch it - your body simply has to be making a better ground than the amp is providing! The noise is from some form of electrical interference. If touching it stops it then you are shorting it out.

Or to put it another way, I'm not saying the bridge isn't connected to the guitar jack ( but I'd still want to test that)- I mean it isn't properly grounded by the amp. Therefore the bridge is still not effectively grounded.

A very long cable, high gain amp and high impedance pickups can cause the same effect even when the amp ground is good.

A bridge not grounded to the jack with a good amp ground can be the opposite effect - it's noisy when you do touch it. You can't be the better ground in that case.

I understood your point to be that if the guitar was properly grounded, touching it would NOT make the hum go away.  If that was not your point, then yes, I misunderstood your statement and please accept my apology.  But that statement, as I understood it, whether your intention or not, is false.

You're right - the body can shunt "electrical interference" to ground - but of course the body needs to actually be grounded to do that.  There was no indication of that by the OP, and typically most guitar players other than pappasmurfsharem are not grounded, so I think we can safely assume that isn't what's happening here.  Except when the strings are touched, because then the body is grounded via the strings, and noise is shunted to ground.  This is the more likely scenario - the body itself is at least one source of hum via capacitive coupling, and touching the strings shunts this noise to ground because the guitar is grounded.  This is very common - the telltale sign is the reduction of noise when the player touches the strings.

Another factor that I think applies in this case (experts please correct me if I am wrong) is the potential for the body to act as a shield against interference.  Since the body is conductive, placing it between a source of the interference and the pickups and grounding the body (for example to the strings of a properly grounded guitar) does provide a shielding effect, although not likely a good one.

[Xavier]

I am by no means any expert in electronics, but at least in my case all the guitars I've played are like that. I have 7 electrics and all of them hum when plugged in without touching them. The minute you put your hands on the strings or the bridge, it goes away. It's just the nature of the beast I think.

Shielding sounds good in theory, but (specially on strats) it will kill your high end -been there-, I would rather go for noiseless pickups like the Kinmans or EMG's in case you like actives.

I've also found that sometimes EMG equipped guitars have the bridge not connected to ground (in theory it's not needed because the pickups are "so quiet" )

[GibsonGM]

30 ohm is a lot for the bridge ground.
In a LP - isn't the wire pushed inside the bridge pillar hole and trapped by the ferrule?

+1, what I said above.  Look right below the big yellow outlet tester      

I would redo the ground if I measured that on MY instrument....until there is just about ZERO ohms from bridge to the ground on the jack, we really can't say too much more.   And I mean near ZERO...like, .1 ohm because your meter isn't precise enough to read ZERO.
There is only a 5" piece of wire from bridge to ground at the jack!   30R is too high.

[ashcat_lt]

Shielding sounds good in theory, but (specially on strats) it will kill your high end -been there-,...

This is only true if you try to shield the pickups themselves.  If you wrap a grounded loop of foil around the pickup coil, there's capacitive coupling from the wires of the coil to the shield.  What do we call a capacitor from signal to ground?  Right, a low pass filter.  It should be about the same thing as putting a metal cover on.

When you shield just the cavities (and pickguard in a strat) you don't usually end up with enough foil close enough to the coils to get much capacitance.  In an LP there won't be foil anywhere near the pickups.  I have shielded most of my guitars, and most of them can be ice picks if I want.  Yes, this leaves the big coil of wire which is going to pick up most of the noise outside of the shield, but the side pointed toward the biggest, closest source of noise (you) is usually shielded, and as mentioned above, some pickups have metal covers and are shielded already.  For the rest, we have humbucking combinations of coils or we accept the fact that single coil guitars him a bit, and that we've done the best we can to minimize the noise.

No real world passive guitar is ever going to be completely silent until you turn the V pot all the way down (or flip the kill switch!), and I think it's important to have some perspective.  I drove myself (more) crazy one summer by cranking up my headphones and tracking down the source of every tiny little buzz and hiss in my studio.  It was horrible!  Ultimately helped quite a bit, but if I had actually played music through the system at that volume it would have destroyed the cans and my ears.  The best we can hope for is a reasonable S/N ratio.  We'll never achieve in a guitar anywhere near the specs we expect in "pro audio" equipment, let alone what's available even in digital.  A little bit of buzz that only happens when you're not touching the guitar, and can't really be heard (if if you're not touching) when the strings are ringing is not a problem, it's a disorder.