60Hz hum in my Les Paul

[Dimitree]

hi everyone

I know it's an old question in many forum, but I still can't understand if it is normal or not..so since this forum is the most tech-related I'm sure I can get a proper reply.

when I don't touch anything metal on my Les Paul (2 standard humbuckers) I hear an annoying 60Hz hum (50Hz actually since I'm in EU).
I recorded it here:
https://soundcloud.com/dimitree-1/noise-lp

as you can hear, the guitar is silent when I touch strings or metal parts. Furthermore using the volume knobs, it makes some sort of filtering of the noise.

details:
- the wiring on my guitar is made by me following the Seymour Duncan wiring diagrams.
- I'm not using an amp here! so it's not an amp problem, I'm recording directly to my USB audio sound-card. This card is a Focusrite Scarlett 18i6, powered by its original 12V DC power supply. This psu only have 2 conductors that goes to the main outlet, not 3 (so no ground).
- btw, the same problem happens when I'm playing with other amps (and in other places, not only in my house).

many people says it's totally normal, many people says that it is not since they guitars don't do that.
What's the truth?

[induction]

Sounds like the bridge isn't grounded.

[R.G.]

First, good work for eliminating a lot of things it could be - house wiring, amps you're connecting to, etc.

I think "induction" could be right - an ungrounded bridge could do this, as could a broken wire inside the control cavity.

Does the hum level change with the setting of the guitar controls at all?

[Dimitree]

the bridge is grounded (and so the strings, the tuners, the jack plate, and so on), indeed if I touch it, the hum disappears. There's continuity between every point that should be tied to ground, so no broken paths.

yes, the hum level changes when I move the volume pot, as you can hear in the clip, it totally disappear with volume at 0, when volume is at 85% the hum is at his max, and when volume is at 100% it sounds a bit high-pass filtered. (you can listen those things in the clip)

[GibsonGM]

Have you tried another axe to see if it still occurs?

Lots of times you can have a 'floating' power supply - a difference in potential between say computer PS and your 'add on's' power supply...happened to me with powered PC speakers and it drove me crazy!!!....I am not 100% sure you are actually at ground potential with the LP!    If the bridge etc. is in fact grounded, I am very inclined to think the problem lies in having a couple of different ground references.   In essence, there is 'no clear point of zero volts as reference', if what I think is correct.  

Plug everything into 1 power strip, check the wall outlet with a tester to be sure it's wired right, try another guitar, make sure you're not using any pedals at the time and then introduce some, try YOUR guitar with a good amp, etc....if the problem remains, well OK, we'll blame the axe, but I wouldn't just yet    

PS - anything nearby that could cause hum induction, like a transformer, or the PC screen or something?  I have to turn my monitor off when I record!!   

[GGBB]

AC hum that goes away when you touch grounded metal doesn't necessarily indicate that there is something wrong with the guitar or amp/whatever, other than perhaps insufficient shielding.  Most concise and clear explanation I've come across:

https://www.audereaudio.com/FAQ_PUNoise.htm

[ashcat_lt]

Yep, the fact that the noise goes away when you touch the strings indicates that the bridge is in fact grounded and everything is working normally.  The noise comes from you, or (perhaps more accurately) you are acting as a "rebroadcasting station" for the EM/RFI radiation in your environment.  Perfectly normal. 

A typical Les Paul has a rather long run of wire from the pickups up to the switch and back down to the control cavity.  These wires as well as the controls in the cavity itself are prone to pick up some noise if not shielded properly.  You might try just lining the cavity and its cover with aluminum or copper foil.  Make sure that the foil on the cover contacts that in the cavity when screwed in place, and that the cavity foil contacts something else that is grounded like a pot shaft/nut, or the metal plate that they are sometimes attached to, or even a wire screwed into the side of the cavity that is connected to ground somehow.  That will likely help some, but if it's not enough then you'll want to replace those wires running to the switch and back with something shielded.

[Dimitree]

I don't think (but of couse I may be totally wrong) that it is a EM/RFI problem.

I have the same problems when I use my stratocaster..
Furthermore, when my chain is
guitar -> battery powered headphone amp
touching or not touching the metal parts makes no differences, because cycling hum is not there at all.. So I'd say guitars are ok. right?

And last, when I plug my condenser microphone to my usb audio card, there's no noise, but if I touch the mic metal chassis, 60hz noise comes in! then, while touching the mic chassis, if I touch the mic jack (metal) noise stops again!

[ashcat_lt]

I don't think (but of couse I may be totally wrong) that it is a EM/RFI problem.

I have the same problems when I use my stratocaster..
Furthermore, when my chain is
guitar -> battery powered headphone amp
touching or not touching the metal parts makes no differences, because cycling hum is not there at all.. So I'd say guitars are ok. right?

It is ElectroMagnetic noise, being spewed into the air either by the wires in your walls or by some transformer(s) connected to those wires.  It is, as I said, sort of collected and rebroadcast by the nice sack of electrolytes that you call a body, which is very (!) close to the wiring in the guitar, which picks it up and sends it to whatever you're plugging into for amplification/recording.  When you short yourself to ground by touching the strings, you also short the noise.  It's how it's supposed to work.  Your strat also needs to be shielded.  There are plenty of other variables to account for the thing with the headphone amp.

And last, when I plug my condenser microphone to my usb audio card, there's no noise, but if I touch the mic metal chassis, 60hz noise comes in! then, while touching the mic chassis, if I touch the mic jack (metal) noise stops again!

That almost indicates that somehow the chassis of your microphone is not actually conducting to the shield of the cable.  By touching the metal case you are focusing the noise that you're rebroadcasting even closer to the electronics inside so it can more effectively interfere with your signal.  This is very similar to touching the pole pieces on many guitar pickups.  By connecting to the actual grounded part of the cable, you are again shorting your noise, just like touching the strings/bridge on your guitar does.

Shield the guitars, live with the hum, or turn off the main breaker to your building.  

[GGBB]

I don't think (but of couse I may be totally wrong) that it is a EM/RFI problem.

AC hum can be "rebroadcast" by your body as well.  The telltale sign of insufficient shielding is that the noise - whichever type - goes away when you touch grounded metal.  That indicates that the source of the noise is you, or more specifically the voltage imposed on your body by the local AC line power system via capacitive coupling, which is in turn imposed on the pickups via capacitive coupling.

[Dimitree]

thank you guys,
but how do I explain the fact that if I put the guitar on the sofa, I start recording and I go to another room (the guitar still on the sofa), the noise is still there (constant and at the same level) even without me?

Shield the guitars, live with the hum,

I can't see why I should live with this cyclic hum..
A friend of mine has a home studio, he got a cheap squier telecaster with no shielding at all, and he got no 60hz hum when he doesn't touch the string.
He actually got noise when he is near a monitor or near a cellphone, but in this case it's ok, I accept that it is normal and related to shielding and I can live with this. I can even live with white noise/hiss produced by pickups, it's ok.
But my guitars let me hear 60hz hum in every condition, and I think it is not acceptable.
Unfortunately I can't go with my guitars to my friend house and try there.
So, if my situation is normal, my friend's one is not, or the opposite.

[poojalooba_cow]

You gotta go with the shielding option if you want to eliminate it.  Tons of different things affect electromagnetic hum, which is quite easily picked up by sensitive guitar equipment and sensitive amplification circuits.  The wiring in my family's house is super quiet and nice - I do my recording there because there's no hum.  At my apartment, the entire building is very poorly grounded and there are so many other people using electronic stuff around me that my amps hum noticeably all the time - and while it's fine for playing, I would never think of trying to record in a situation like that.  

The fact that your headphone amp is battery-powered and doesn't produce hum makes me think it's definitely a problem with something in the AC circuitry surrounding you - in the walls, your appliances, your neighbors' place, etc.

Maybe your friend's studio has well-done wall wiring and your building doesn't.  Maybe your friend doesn't have things like a refrigerator, microwave, AC unit, Internet routers, etc nearby that can contribute to electromagnetic hum.  Maybe your friend's studio has a lot of steel girding in the ceiling that blocks (effectively "shielding") outside radio, TV, and cell phone transmissions.  Maybe your headphone amp is small enough or well-shielded enough that it doesn't pick up any hum from things around you.  It all really depends, but if you want to eliminate as many possible sources of hum as possible, shield all the stuff in your guitar. If it persists even after that, THEN you really have a reason to complain.

[GibsonGM]

Great suggestions, everyone.    Shielding is called for, yup.   Really does sound like "the body antenna" effect.    And if that doesn't work, I guess an active 60 Hz hum filter! 

[Dimitree]

Really does sound like "the body antenna" effect

Funny, the same thing happens when I leave the guitar on tue sofa, 10 meters far from me..

[GGBB]

Really does sound like "the body antenna" effect

Funny, the same thing happens when I leave the guitar on tue sofa, 10 meters far from me..

Human bodies are not the only objects capable of capacitive coupling with mains wiring and guitar pickups.  Anything that can conduct - like our bodies - will technically do this.  Does the sofa have springs?  If the sofa touches the strings does the hum go away?  What kind of pick does the sofa play with?  If you have a long enough cable, take the guitar outside and well away from the building.

[ashcat_lt]

Well, the thing is, we're offering you a solution that has helped many other folks with similar symptoms, that's relatively easy and can be quite cheap, and (done correctly) can't possibly hurt.  On top of that, I really can't imagine any other problem that would actually fit the scenario that you've described.  If the hum did not go away when you touched the strings, or actually got worse, we might look elsewhere, but for now I'm going to continue to say "shield it or live with it."

Edit to add - even if it's not all body noise, shielding can only help.

[Dimitree]

The hum has the same level wherever I put the guitar, wherever room, with or without me.
If it was a ground loop or an earth connection problem, would it give me the same signs? Or can we exclude that since qhen I touch the strings it is mute?

[amptramp]

Don't overlook bad wiring practices in the guitar.  This Cort has two volume controls and a tone control:



It had serious hum and noise issues.  Adding the yellow grounding wire solved the problem.  Originally, ground connections from the pots were made from the ground lug to the metal rear shell and the pots were connected via the front shell being compressed against an aluminum tape shield.  No good contacts anywhere, including the bridge ground.  I left the connections from the volume controls to the rear metal shells since the shells do not necessarily make good contact with the front face of the pots.

Now it plays well with no sign of hum or noise:

[ashcat_lt]

There's no ground loop inside your guitar.  There may be some redundant ground paths, and I've heard tales of folks breaking those and getting better noise performance, but they almost always do a bunch of other stuff (like shield the thing) at the same time. 

Far more often I've seen people who couldn't fix their hum without adding a redundant ground path - usually the wires between the pots which they removed when they shielded and star grounded it.  It is completely possible that you've got some dodgy ground path.  Either the bottom of the pickup or the cases of the pots might have more than insignificant resistance to the jack sleeve.  Generally, though, touching the strings won't cure this.  You'll have a reduction in hum any time you touch a ground point, but there will still be a residual buzz.

If there's a ground loop in the rest of your setup, then it will buzz even without the guitar.

It's worth a shot to double check all of your wiring, maybe reflow some of the ground connections.  While you've got it apart, you might as well shield it. 

[Beo]

Why not eliminate all variables. Shield the full interior... take the time and expense that most manufacturers do not do... (not that it's expensive... it's the cheapest improvement you can do). If you still have really bad 60hz hum, then you can go after the wiring and the ground paths.

60hz house wiring should be obvious when moving around your amp, rotating in spot, or moving your amp around the house causes the noise to get better or worse. Shield the cavity, and check your wiring. Also, plug the guitar direct into amp, and maybe try other amps too.

I'm a basement player in a small room... house wires all around me. My strat can be awful, even with shielding. Maybe try in your back yard?