Les Paul star ground wiring (or other silent ones)

[uldericom]

I made a search but didn't find anything,
Could anybody show a star ground wiring diagram for a two pickups (standard ones, brided wire) LP custom (two volume pots, two tone pots.....?

I have to rewire it, I would like to see this option, many people talk about it but nobody seems to be able to show its specific config.............

I have three LP and they all are buzzing (the type that disappears touching strings, so it's not a disconnected ground question), while a Paul Reed Smith I also own is silent as a tomb (and well playing.....). Seems that all LP are good antennas, ground loops or not. The PRS is not shielded, for me it's surely a problem of wirings. The fact that all three are noisy seems to exlude a problem of bad welding or cabling, even if they all anyway appears poor.

That's the reason I'm looking for an alternative scheme to rewire at least one. The buzz is not a problem for standard playing, it is so when you record in a PC workstation, by means of an ampli headphones connection.

Thanks in advance

[newey]

uldericom-

Ciao e benvenuto a Guitarnutz2!

While star grounding is a good electrical practice, it is unlikely to have a significant effect upon noise. It does eliminate "ground loops", but as a group here we've pretty well concluded that ground loops are not usually a noise-generator. JohnH did some research on that question, he wired his guitar ground to the entire heat/ventilating system in his house, making the whole thing one huge ground loop- with no increase in noise.

We can certainly show you how to star-ground an LP, however, if you wish to try it. But I suspect your noise problems lie elsewhere.

You mention that you have 3 LPs that are noisy and a PRS that isn't. I will assume that you've tested all three through the same amp, same gain settings, same cable, etc.

Are these LPs equipped with HBs or P-90s? HB-equipped LPs are usually pretty quiet. It is particularly odd that all 3 of yours have a noise issue.

Do you perhaps have the pickups adjusted way up, to just underneath the strings? Are these real Gibson LPs, or clones or knockoff versions?

If you do wish to star-ground one of the two, it would probably make sense to shield the control cavity as well. The shielding will help reduce noise if one of the controls is causing the problem.

It's tough to shield the pickups on an LP, especially if they're metal-covered HBs- but HBs shouldn't be very noisy anyway.

Anyway, I'll look for a star-ground diagram around here, but the basic principles are the same as any guitar. All the grounds are collected at one point, and that one point is then wired to the output jack sleeve/barrel connection.

This means unsoldering all the connections from the backs of the pots, and then running those grounds to the grounding point. Be careful not to apply too much heat to pots when desoldering, do it one wire at a time and don't leave your iron on the back of the pot for too long.

If you've shielded the cavity, the "ground point" can be a washer screwed into the side of the cavity, which then grounds the shielding by contact with the screw.

[uldericom]

Thanks, newey, fine suggestions: I'm not so sure that ground loops have no influence in noise generating; I think that they only generate an antenna effect, so if there are ground loops but no radio or AC disturbs the noise is not generated anyway...... or not.........

I answer that gear (amp, cable, etc) is absolutely the same
3 LPs buzzing (not so much, but annoying, expecially that on/off effect when touching strings )
1 PRS zero noise
1 ES335 almost fully silent

You say that all grounds must be collected to a common (star) point.
What about the cloth of the braided wire from pickups? It is both negative/ground together, I think, where has it to be sent/welded ?

Thanks

[Deleted]

Nov 4, 2012 9:38:36 GMT -5 uldericom said:

Thanks, newey, fine suggestions: I'm not so sure that ground loops have no influence in noise generating; I think that they only generate an antenna effect, so if there are ground loops but no radio or AC disturbs the noise is not generated anyway...... or not.........

I answer that gear (amp, cable, etc) is absolutely the same
3 LPs buzzing (not so much, but annoying, expecially that on/off effect when touching strings )
1 PRS zero noise
1 ES335 almost fully silent

You say that all grounds must be collected to a common (star) point.
What about the cloth of the braided wire from pickups? It is both negative/ground together, I think, where has it to be sent/welded ?

Thanks

you don't answer newey's most important question. Are the LP's humbucker equipped or not (P-90)? HB's have no issues with hum unless the wiring is totally messed up.

[uldericom]

Sorry, I noticed after posting and board seems not allow subsequent replies....

metal covered humbuckers, various tipe, but all Gibson and with braided wires

[Deleted]

Nov 4, 2012 10:39:58 GMT -5 uldericom said:

Sorry, I noticed after posting and board seems not allow subsequent replies....

metal covered humbuckers, various tipe, but all Gibson and with braided wires

ahhhh...

i have a les-paul-ish Ibanez which i have not "studied" yet, but i guess the 2 pups, 2-tone, 2-volume configuration is pretty common. Hmmmm is there any "debugging" procedure for Les-pauls?

although aimed at strats mostly, you can see some good guides in the original GN site here :

[uldericom]

Thanks pyrros,
I alredy red that two guides, they confirm my opinion

• harsh buzz=Unshielded or poorly wired guitar of any type.
  
  
• the second one shows a shielding job, unuseful for me if point no. 1 is not satisfied
  
  

that the reason why I ask for star grounding infos

[Deleted]

Nov 4, 2012 12:22:50 GMT -5 uldericom said:

Thanks pyrros,
I alredy red that two guides, they confirm my opinion

• harsh buzz=Unshielded or poorly wired guitar of any type.
  
  
• the second one shows a shielding job, unuseful for me if point no. 1 is not satisfied
  
  

that the reason why I ask for star grounding infos

IMHO no shielding is needed in the case of humbuckers. I mean hum-buckers by definition buck the hum. I had a strat partscaster with single coils and because of this guitar i joined the forum. I did substantially shielding job, followed all guides,bought all the needed capacitors, tried aluminum tape, and then conducting paint/coating for the cavities, aluminum pickguard shield for the pickguard, and i saw some improvement, although the hum was still there in certain positions/orientations of the instrument. Then i install Dimarzio Super Distortion in the bridge and Dimarzio HS-3 in the neck and the hum went completely off. Because of the fat humbucker in the bridge i could not even hold the aluminum shield any more under the pickguard (it wouldn't fit). (i think i may have sold it). Now it still hums in positions 2-4, but i rarely use distortion on those. I also had an old strat-copy Aria with Dimarzio fast-track1 and fast-track2, neck/bridge. Likewise no hum there, with *NO* explicit shielding anywhere on the guitar.

So i would say just "poorly wired" cannot explain the hum in the case of humbuckers, unless the amounts of distortion and excessively high. Maybe it has smth to do with grounding ?

[Deleted]

Maybe also this ? :

www.thegearpage.net/board/archive/index.php/t-905053.html

[Deleted]

and this! :

[uldericom]

It's not a ground issue, I told about on/off effect touching string meaning that buzz disappears just touching them. So grounding is fine.
It's probably a ground loop: a disturb coused by radio or AC power is collected by wiring, acting as antenna. Bad wiring or ground loops causes this antenna effect: the human body works as a shield.

And........
having all three LPs making the same buzz, I suspected it was typical of their wiring design, this is the reason why I asked opinions about something different like star grounding.

I don't think that 50s or modern wiring design can introduce something different from the one I have actually in my LPs, about better grounding properties point of view.

Surely my ones are not well done, and this is very important....good quality weldings, good cables, good components.....will help a lot, but more or less the grounding design is the same.

[Deleted]

Hmmmm,

if i were in your shoes, and since your symptoms sound "normal" : touching the strings makes the hum disappear, the first thing to look would be the pups. I mean, your guitar behaves exactly like a healthy single-coil stratocaster, right? Change one pup with a "proven" one (e.g. Dimarzio super distortion) and see if you have some change. You definitely have to account for pups as well. I have seen poorly made cheap humbuckers hum and buzz. I guessed from your description that maybe Gibson was supposed to be "high-end"/good/superb/etc... but it never hurts checking. Good humbucker pups from good manufacturers should be 99.99 hum free. I had hum noise troubles with a cheap artet rails mini-humbucker but never with fast-track1/2.

[uldericom]

Good idea, it worth a try

[newey]

uldericom-

Sorry, I meant to move your post earlier, but forgot to do so. It really belongs here, in Wiring. But no worries, we give newcomers a free pass on this sort of thing.

If these are 2-conductor (1 conductor plus braid) style HBs, then yes, the signal is going through the braid. This only becomes an issue if you want to do out-of-phase wiring or series wiring. In a std. LP scheme, the braids are currently wired to ground; when you star-ground them, they will still be wired directly to ground, just to a different spot. Electrically, it's the same.

pyrros is right, cheap components can be sources of noise, as can cheap pickups. Before rewiring anything, please perform this simple test:

Plug in one of the offending guitars and listen to the level of hum/noise. Then lower both pickups until they are basically flush with the body. Any change in the noise level? If there is, it's likely that the pickups are a major source, and rewiring in the cavity area is unlikely to change anything. Potting the pickups sometimes helps.

If there's no difference in the noise, then perhaps it is being generated from one or more of the components in the control cavity. Again, star-grounding alone is unlikely to change anything, but shielding the cavity might help.

You are correct that, in theory, a ground loop can act as an antenna. The key words there are "in theory". The extent to which a ground loop will act as an antenna is a function of its length, and the short lengths of wire in your cavity are unlikely to be picking up much of anything.

Your pickups, on the other hand, are wound with thousands of feet of wire. They make excellent antennae, and are the source of most noise. That's why humbucking pickups make such a difference, and why Strats and other SC guitars benefit from shielding the pickup cavities.

I'll come up with a star-ground diagram for an LP if you want one, but again, I recommend coupling that with a shielding job, at least for the control cavity. Otherwise, odds are it won't do anything much for your noise.

It's pretty tough to do much shielding around the pickups in an LP. We've had folks experiment with wrapping the back and sides of the pickups themselves (as opposed to shielding the cavity, as in a Strat) with copper foil, but that can affect the tone. Those who have done this report mixed results- some raved about it, others said it dulled the pickup's tone too much.

[Deleted]

newey great analysis, just a quick one : why would increasing the pup distance from the strings result in decrease of the hum effect, in case of badly made pups? Shouldn't the badly made pups hum no matter what?

[newey]

why would increasing the pup distance from the strings result in decrease of the hum effect, in case of badly made pups? Shouldn't the badly made pups hum no matter what?

Exposing more of the pickup above the body can increase the noise, as the wood of the body does shield things to some extent- nowhere near as well as a metal shield, but the difference can sometimes be audible.

Or perhaps not audible, this isn't a definitive check of anything. If there's no change, it doesn't mean the pickups aren't the cause.

Of course, lowering the pickups also means less output, but here we're speaking of noise without strumming or picking the strings. I'm not suggesting that lowering the pickups is an acceptable solution, just as a test to see if the source can be pinpointed a bit better.

And uldericom-

It's not a ground issue, I told about on/off effect touching string meaning that buzz disappears just touching them. So grounding is fine.

Not necessarily true; it means that your string/bridge ground is fine, but doesn't tell us anything about the grounding of the electrical components.

the human body works as a shield.

Nope, just the opposite is true. Your body is a major source of noise, and you're not particularly well grounded, unless you're standing barefoot in a puddle of water.

By touching the strings, which are grounded through the bridge, via the ground wire (and ultimately are grounded to the amp), you ground yourself and reduce the noise.

[ashcatlt]

Nov 4, 2012 12:57:40 GMT -5 uldericom said:

...the human body works as a shield...

Nope, the human body acts as an RFI/EMF antenna. Not only do you produce a whole buttload of noise yourself, but you also help to focus the noise in the air around you.

Touching the strings shorts you out. (Oh, I guess newey said that)

My Les Paul Studio came from the factory star grounded. There's a metal plate to which the pots are attached. The braids from the pickups, the tone cap, and the sleeve of the jack all collect at a solder lug attached to that plate.

That guitar is pretty noisy. There's a pretty long run of wire - through the innards of the guitar from pickups to cavity to switch to cavity. If this is unshielded it's kind of like using a speaker wire to plug your guitar into your amp.

[JohnH]

I think that LPs well wired can be very quiet, provided that the pickups are with metal covers and baseplates grounded, and all wire runs from pickups, up and down to the toggle switch and to the jack are shielded, pot cases are grounded, bridge grounded. There’s very little left to pick up noise, except a few component wires.

I don’t think ground loops are relevant in a guitar. The only extra thing you could do is shield the switch and main control cavities with foil or conductive paint, and ground that.

One thing that may be a factor on Gibson v PRS is that i think that some Gibson hum-bucker pickups are designed with slightly unbalanced coils, to give a bit more high end tone, and also therefore a bit more noise due to not quite cancelling each others hum.
J

[Deleted]

Great points by all. Newey, thanx for clearing this up.

[uldericom]

Thank you very much for explanations and suggestions, I'll try newey tests.
At the end we can say, as per all the rest of life things, that there is not a single solution, but a sum of contributing factors......
Anyway, just for my knowledge, I kindly ask newey the star ground diagram he mentioned.

ashcatlt says That guitar is pretty noisy. There's a pretty long run of wire - through the innards of the guitar from pickups to cavity to switch to cavity. If this is unshielded it's kind of like using a speaker wire to plug your guitar into your amp.

I think this is a good observation, my lp's are all wired from switch with that 3+ groung cable not shielded.........
What is your opinion with traditional switch rewiring with braided wires (three braided wires with clothes connected to ground)? Isn't there a better cable?

[JohnH]

I think it is well worth having shielded cable for the wires up to the switch cavity and back to the jack. It could be metal braided, or just shielded audio cable of some kind. It should give an inprovement over plain wire.

[newey]

JohnH and Ashcatlt make good points about using shielded cable for the cable runs inside the guitar. I don't own an LP so I hadn't thought of that. You should definitely shield those cable runs. Bear in mind that shielding the cables only works if one end of the shielding is then run to ground- to your star-grounding point if you're going to do a star-ground.

You can "repurpose" any multi-conductor cable for this so long as it fulfills 3 criteria. It must have enough conductors inside it. It needs to have large enough conductor wires that you can work with them. And it needs to have a braided metal shield, not just the mylar plastic wrap, as you need to be able to solder to it to ground it at the end.

The first diagram below is a wiring diagram for a stock 1957 Les Paul. Yours should be similar. Note that this diagram doesn't show the bridge/string ground wire. Also note that all the grounds are shown by the black wires. First, you desolder all those from the backs of the various pots.

The diagram also shows the jack sleeve wired to a ground, but the actual point is unspecified. On your guitar, it likely goes to the back of one of the pots as well. It also gets desoldered.

The diagram also doesn't show any grounding between the pot shells. It is likely that there are some bare wires between the backs of all four pots on your guitar. You can leave those wires in place, and then just ground the back of one of the pots to the star ground point. I didn't show this on the diagram for clarity's sake.

The bare grounds between the pot shells do not constitute a "ground loop" as they are not attached to any wires carrying signal (until they reach the star grounding point). These wires cannot be the source of noise in your signal, since they don't carry any signal.

If you shield the cavity, the pots will be grounded through the shielding and it is then not necessary to gorund the backs of the pot shells.



This second diagram shows you how to star ground it. The black wires get disconnected, and they get reconnected as shown by the blue wires.

[uldericom]

Thanks a lot newey, let me say that is a pleasure discuss with such a polite and available guy ;D

About diagram, I'm a little bit confused: having to rewire completely new (and it should be a grat goal avoid pots case soldering ), the blue connections you drawn bring to the exlusion of the old continuing ones? As follows? (I added switch ground)


Or, in case of pot cloth soldering, the wiring could be the following (trying to save wiring connections?


and what about the bare wire to connect pots? As you can see I'm trying to find the less complicate configuration, just to avoid mistakes in welding or samthing related to my low skill in this kind of activity

[newey]

Adding the switch ground, which you show as a green wire, is fine, I had forgotten that.

The blue wires are in place of the original black wires. As I said, the original grounds to the back of the pots need to be desoldered, and then re-run as shown in blue.

If you leave the black connections as they were originally, and add the blue wires in addition to the black (as you show in your diagram), you will have created more ground loops. A ground loop, by definition, is where you have two paths to ground for the same component.

Or, in case of pot cloth soldering, the wiring could be the following (trying to save wiring connections?

I don't know what you mean by "pot cloth soldering", I think we're having a translation problem there. Again, if you mean can you leave the braided shields connected to the backs of the pots, the answer is "no", it's not star-grounded if you do so.

and what about the bare wire to connect pots?

As I said earlier, you can leave those as they are, so long as they ultimately are connected to ground, either via a separate wire to the star ground or via the cavity shielding if you are doing that.

At the risk of repeating myself, I seriously recommend both a cavity shielding job as well as running shielded cable. The star grounding by itself is unlikely to affect your noise levels. If you're going to rewire the guitar anyway, you might as well do the job thoroughly.