smalaney Posted March 12, 2012 Share Posted March 12, 2012 Last May (2011) I purchased a 1960's Custom Shop Les Paul from Guitar Center. After fixing some obvious problems (tubes, loose wires) on my new Fender amp, it became quite clear to me that the "hum" at medium to high volumes was coming from the guitar. The local Gibson repair center noted a few things. 1) No shielding on the either of the body cavities 2) Ground wiring incorrect 3) Non-standard pots (no Gibson name on the back of the pots) 4) Different impedance between the Bridge and Neck pickups. I took my 1964 vintage Musicman guitar (with built in pre-amp - shielded body cavity) hooked it to the same amp, no "hum. Now it has been a number of years since I got my electrical engineering degree, but as hi-gain preamps on guitar amps have come to predominate the scene, shielding the electronics in the guitar is done specifically to cure this kind of (hum) problem. Gibson guitars previous actually had metal casing around the pots, etc specifically to eliminate these kinds of problems. I have contacted Guitar Center, but wonder is anyone else seeing these kinds of "quality issues with the guitars they buy from Gibson. I have always wanted a very nice, playable Les Paul, and after saving up for it (and numerous arguments with my wife about spending so much money on a guitar) I feel cheated. The guitar is still under warrantee, and it looks like the service center will try to get me a new set of pickups, but frankly, I would be hard pressed to recommend this (or any other Gibson Guitar) to anyone I know. smalaney Link to comment Share on other sites More sharing options...
Gary Moore Tribute Posted March 12, 2012 Share Posted March 12, 2012 I own a number of Gibson Les Pauls and have a mix of 50's wired and Current 08 Std setups In my cases hum is a minor issue (Using a Valve amp) as all my cavities are sat on metal plates I've not come across a Gibson with sheilding, it seems to a owner introduced upgrade for the most part... Regarding "Guitar Centre" they seem to have a colourful history of selling Gibsons with faults still on them that most decent shops would decline and send back on sight. (Kind of shows lazyness) The best thing I can surgest is either have it swapped for another model direct from Gibson or have "Guitar Centre" pay for the Luthier costs to have all these "errors" put right. Link to comment Share on other sites More sharing options...
BigKahune Posted March 12, 2012 Share Posted March 12, 2012 . Sorry to read about your issues. It's unfortunate it took so long to diagnose the guitar issues or you possibly could have exchanged/returned it. Did the items you listed get repaired? In most LPs the bridge and neck pups are different. You could still bring up these issues to the retailer as warranty items or contact Gibson C/S. Regarding similar issues: One comes to mind - in the last year or so there were several posts about malfunctioning 3-way selector switches on certain LP Studio models. Sometimes it was the wiring/solder and sometimes the switch itself. This is a well known issue to some of the regulars here. I think these were all handled by the retailer or Gibson. I've had models that dated back to the 60s and AFAIK Gibson normally doesn't shield body cavities. If you received your LP in a sealed factory box then it would have to be errors from the factory. If not - pots not stamped Gibson and non-standard wiring would indicate the possibly that mods/changes/repairs were made to the guitar before you purchased it. I say that because there's been plenty of posts about Guitar Center putting returned/repaired items back into stock. BTW, a lot of members here wouldn't recommend Guitar Center to anyone. Link to comment Share on other sites More sharing options...
Eracer_Team Posted March 12, 2012 Share Posted March 12, 2012 As far as I know, Gibson does not put any kind of shielding in the cavities of the guitar (tape or graphite paint) can you explain the ground wire incorrect? there are 2 wires coming from the pickups (one is ground the other is the hot signal.) Gibson puts in a ground wire from the bridge/stop tail to one of the pots back cases. can't comment on the pot's installed but the pickups. are you sure they're the same?? a set of pickups like a 480t/490r will have different ohm's for each. Is that why you are stating that the shop is trying to get you another set of pickups???? Link to comment Share on other sites More sharing options...
smalaney Posted March 12, 2012 Author Share Posted March 12, 2012 I own a number of Gibson Les Pauls and have a mix of 50's wired and Current 08 Std setups In my cases hum is a minor issue (Using a Valve amp) as all my cavities are sat on metal plates I've not come across a Gibson with sheilding, it seems to a owner introduced upgrade for the most part... Regarding "Guitar Centre" they seem to have a colourful history of selling Gibsons with faults still on them that most decent shops would decline and send back on sight. (Kind of shows lazyness) The best thing I can surgest is either have it swapped for another model direct from Gibson or have "Guitar Centre" pay for the Luthier costs to have all these "errors" put right. I have heard that the pots and switches usually sit on a metal plate - none of that in the Guitar I bought. Had the repair center put copper tape in the bottom of the cavity, but it still hums like a 100lb bumble bee. I did take this shot of the cavity of a 1970' LP which shows shielded cavity - which I was told came standard on that years model. Link to comment Share on other sites More sharing options...
smalaney Posted March 12, 2012 Author Share Posted March 12, 2012 As far as I know, Gibson does not put any kind of shielding in the cavities of the guitar (tape or graphite paint) can you explain the ground wire incorrect? there are 2 wires coming from the pickups (one is ground the other is the hot signal.) Gibson puts in a ground wire from the bridge/stop tail to one of the pots back cases. can't comment on the pot's installed but the pickups. are you sure they're the same?? a set of pickups like a 480t/490r will have different ohm's for each. Is that why you are stating that the shop is trying to get you another set of pickups???? The repair center stated they would try to get me a new set of Burstbucker pickups, the OHM reading was different enough for them to take note of it. Link to comment Share on other sites More sharing options...
Riffster Posted March 13, 2012 Share Posted March 13, 2012 The repair center stated they would try to get me a new set of Burstbucker pickups, the OHM reading was different enough for them to take note of it. The ohms are supposed to be different to get a balanced sound, The bridge pickup needs to be more powerful because the strings move less as you get closer to the bridge. The difference sometimes is very significant and that is very normal. Shielding is not something you are going to find in a stock Gibson nowadays, they may have had those covers you show for a few years, compared to modern methods of shielding that thing looks like a monstrosity. The hum or grounding issue may be a bad solder connection or a wire touching something, when working on a guitar it has happened to me that a leg on one of the potentiometers touches a wire that is not supposed to. Not all Gibson pots say Gibson on the back, Custom Shop guitars use unmarked pots, they are made by CTS for Gibson though. My 1958 reissue is the same way. I am surprised the guys at the shop you took this guitar to do not know all this. I'd be more worried about them than finding the hum culprit. Link to comment Share on other sites More sharing options...
Searcy Posted March 13, 2012 Share Posted March 13, 2012 1) No shielding on the either of the body cavities If it's supposed to be like a 1960 Les Paul the cavities wont be shielded accept for the control cavity can. 2) Ground wiring incorrect How so? A ground is a ground. Was the ground wire pulled lose from the bridge? 3) Non-standard pots (no Gibson name on the back of the pots) Again, if it's trying to be a replica of a 1960 Les Paul it wont have "Gibson" on the pots. 4) Different impedance between the Bridge and Neck pickups. It's normal for the bridge to be a bit hotter than the neck. What are the readings on the pickups? There might be one with a dead coil. If that's the case then it's a covered by Gibson. I took my 1964 vintage Musicman guitar (with built in pre-amp - shielded body cavity) hooked it to the same amp, no "hum. What does this mean? Perhaps a type-o? The Music Man company didn't exists until 1974. is anyone else seeing these kinds of "quality issues with the guitars they buy from Gibson. I have always wanted a very nice, playable Les Paul, and after saving up for it (and numerous arguments with my wife about spending so much money on a guitar) I feel cheated. I currently have 6 Gibson guitars. The 4 with humbuckers only hum on my Fender amp when the gain is cranked way up or if the treble knob if pegged out at 10 with high gain settings. I'm wondering why you bought this guitar if it hummed so badly. Does your authorized Gibson guitar repair man have no other recommendations as to what might fix your guitar? Link to comment Share on other sites More sharing options...
smalaney Posted March 13, 2012 Author Share Posted March 13, 2012 1) No shielding on the either of the body cavities If it's supposed to be like a 1960 Les Paul the cavities wont be shielded accept for the control cavity can. 2) Ground wiring incorrect How so? A ground is a ground. Was the ground wire pulled lose from the bridge? No - according to the Gibson documentation - the gounding wires were not correctly connected. Gibson documentation show specific grounding wires associated with connections from each pot. 3) Non-standard pots (no Gibson name on the back of the pots) Again, if it's trying to be a replica of a 1960 Les Paul it wont have "Gibson" on the pots. 4) Different impedance between the Bridge and Neck pickups. It's normal for the bridge to be a bit hotter than the neck. What are the readings on the pickups? There might be one with a dead coil. If that's the case then it's a covered by Gibson. I took my 1964 vintage Musicman guitar (with built in pre-amp - shielded body cavity) hooked it to the same amp, no "hum. What does this mean? Perhaps a type-o? The Music Man company didn't exists until 1974. Yes typo- 1974 is anyone else seeing these kinds of "quality issues with the guitars they buy from Gibson. I have always wanted a very nice, playable Les Paul, and after saving up for it (and numerous arguments with my wife about spending so much money on a guitar) I feel cheated. I currently have 6 Gibson guitars. The 4 with humbuckers only hum on my Fender amp when the gain is cranked way up or if the treble knob if pegged out at 10 with high gain settings. I'm wondering why you bought this guitar if it hummed so badly. Does your authorized Gibson guitar repair man have no other recommendations as to what might fix your guitar? He is recommending replacing the pickups so as to eliminate more of the noise. Link to comment Share on other sites More sharing options...
Searcy Posted March 13, 2012 Share Posted March 13, 2012 What did he say the DC resistance was on the pickups? I ask because I can't believe that both pickups had a single failed coil causing the guitar to reasonable output but also unreasonable hum in every pickup position. Does the hum get louder when you touch the strings? Link to comment Share on other sites More sharing options...
DiamondJig Posted March 13, 2012 Share Posted March 13, 2012 Bustbucker pickup will hum more than others, they are made that way, chk gibson's website, they are unmatched coils and no wax potting to match the way they where made in the years days, some pickups will be noisier than others, you may be better off with a pair of classic 57. "On the shop floor of the original Gibson plant in Kalamazoo, Michigan, the earliest Gibson “Patent Applied For” humbuckers were wound using imprecise machines, resulting in pickups with varying degrees of output and tone. The BurstBucker™ line of pickups represents Gibson’s drive to recapture the magic of the original “Patent Applied For” humbuckers. First introduced in the early 1990s, the Gibson BurstBucker™ — Types 1, 2, and 3 — successfully captured the subtle variations of true, classic humbucker tone with historically “unmatched” bobbin windings and Alnico II magnets. They produce an airy, full tone, and when overdriven they achieve a magical distortion with the slightly enhanced highs that made the originals famous. BurstBucker™ Type 1 features a lower output, excellent for the neck position. BurstBucker™ Type 2 features medium output, and is perfect for both positions. BurstBucker™ Type 3 is overwound and hot, which is typically ideal for the bridge position. None of the BurstBuckers™ are wax potted, and all feature vintage braided two-conductor wiring." PS non of my Gibby's have shielding, some have more hum than others Link to comment Share on other sites More sharing options...
Searcy Posted March 13, 2012 Share Posted March 13, 2012 Well, the mis match on a Burst Bucker isn't great enough to induce 60 cycle hum into the signal. Wax potting is done to reduce microphonics and has no effect on 60 cycle hum at all. Link to comment Share on other sites More sharing options...
Riffster Posted March 13, 2012 Share Posted March 13, 2012 Yea, my R8 has no shielding and Burstbuckers and it is pretty quiet. Link to comment Share on other sites More sharing options...
smalaney Posted March 13, 2012 Author Share Posted March 13, 2012 What did he say the DC resistance was on the pickups? I ask because I can't believe that both pickups had a single failed coil causing the guitar to reasonable output but also unreasonable hum in every pickup position. Does the hum get louder when you touch the strings? 7.8 OHMS on the neck PU, 8.1 on the bridge, after we rechecked it theses seem in line with what one might expect. Link to comment Share on other sites More sharing options...
Riffster Posted March 13, 2012 Share Posted March 13, 2012 Yep the ohms are fine, actually Burstbuckers are the same pickup bridge and neck, they have the same pole spacing, they simply place the one that measures stronger in the neck position. Are you getting hum or buzzing? because these are two different things. Link to comment Share on other sites More sharing options...
Tim Plains Posted March 13, 2012 Share Posted March 13, 2012 Was the "Gibson repair center" Guitar Center? Most of those guys are idiots. Maybe there is an issue with this hum you speak of but it seems to me that you just didn't know enough about what you were buying and blamed it on Gibson QC. Link to comment Share on other sites More sharing options...
smalaney Posted March 13, 2012 Author Share Posted March 13, 2012 R9 Posted Today, 04:57 PM Was the "Gibson repair center" Guitar Center? Most of those guys are idiots. Maybe there is an issue with this hum you speak of but it seems to me that you just didn't know enough about what you were buying and blamed it on Gibson QC. ---------------------------- Nice - no it is is a certified Gibson Repair center. The hum as it were has been getting progressively worse since I bought the guitar. Since I work a 50+ hour week, i had not had a chance to play the guitar or amp at much above "house" volume, so the noise was not very noticeable. Also, practice is a bit different than playing out. I asked specific questions about the guitar when I bought it, played probably 6-8 Guitars, and liked they way this one played. To assume "I did not know what i was buying" is a pretty big leap. Humbucking Pickups are intended to reduce hum. these do not. Link to comment Share on other sites More sharing options...
Searcy Posted March 14, 2012 Share Posted March 14, 2012 I'm not trying to bust your balls. I'd like to help you out but you claim there is a shielding issue and poor Gibson QC yet nothing you are describing so far sounds unusual for a Gibson to me. If there was an improper ground your repair man should have quickly fixed it and you should be happy. If there is some other problem it isn't apparent from your comments so far. Pickups? I don't think that's your issue. I asked before if the guitar hums more when you touch the strings than when you are not touching them. While rare it is possible for this to happen if the jack is wired backwards. There are two scenarios where my Gibson Raw Power Les Paul with the shielding can in place will buzz while using my Fender Vibro Champ DX amp. The first is if I sit to close to the amp. If my guitar is about 2.5 feet from the amp the transformer in the amp will cause it to hum. This is normal. It's not a defective pickup. There is a fix though. The fix is to use a longer cord and sit a little farther away. The second is if my wife turns on the bathroom light while I'm playing. This is because the bathroom lights in my house are on a dimmer and they run on the same circuit as the outlet that my amp is plugged into. The fix for this is to turn off the light or switch over to my Marshall or Solid State amps which are much less noisy. It might be worth your while to get a long cord and try walking around the room while you play and see if the noise gets better or worse. Also, try plugging the guitar in at the Guitar Center where you bought it and see if it goes away on different amps. Buzz and hum issue can be a pain to track down and it may be that something is wrong with your guitar but don't be to fast to take this repair guys words for it that Gibson is to blame when so far he seems to be unable to resolve the issue. Link to comment Share on other sites More sharing options...
smalaney Posted March 14, 2012 Author Share Posted March 14, 2012 I'm not trying to bust your balls. I'd like to help you out but you claim there is a shielding issue and poor Gibson QC yet nothing you are describing so far sound unusual for a Gibson to me. If there was an improper ground your repair man should have quickly fixed it and you should be happy. Pickups? I don't think that's your issue. I asked before if the guitar hums more when you touch the strings then when you are not touching it. While rare it is possible for this to happen if the jack is wired backwards. There are two scenarios where my Gibson Raw Power Les Paul with the shielding can in place will buzz while using my Fender Vibro Champ DX amp. The first is if I sit to close to the amp. If my guitar is about 2.5 feet from the amp the transformer in the amp will cause it to hum. The fix is to use a longer cord and sit a little farther away. The second is it my wife turns on the bathroom light while I'm playing. This is because the bathroom light are on a dimmer and they run on the same circuit as the outlet that my amp is plugged into. The fix for this is to turn off the light or switch over to my Marshall or Solid State amps which are much less noisy. It might be worth your while to get a long cord and try walking around the room while you play and see if the noise gets better or worse. Also, try plugging the guitar in at the Guitar Center where you bought it and see if it goes away on different amps. Buzz and hum issue can be a pain to track down and it may be that something is wrong with your guitar but don't be to fast to blame. I have tried plying the guitar with 6-8 different chords, 12 different locations, over a period of about 3-4 months trying to isolate the problem. I also have my entire office running on isolated ground circuits as I work on computers all day - which are turned off when I am practicing most of the time. I have tried other guitars in the same setup (mine and borrowed) and for the life of me I cannot figure out why this particular guitar is so noisy. Beats me. As I stated in the original post - my 74 Musicman (which I shielded with copper tape) is a quiet as a mouse with the same setup. After all this, and some analysis by a couple of electrical technicians who make their living troubleshooting circuits, RF noise, etc., they all pointed to the same thing - the pickups. Link to comment Share on other sites More sharing options...
Searcy Posted March 14, 2012 Share Posted March 14, 2012 And what does this large team of experts say is wrong with the pickups? Link to comment Share on other sites More sharing options...
smalaney Posted March 14, 2012 Author Share Posted March 14, 2012 Not much to say. Unless they take them apart and examine the windings, it is purely a process of elimination. Guess i will close this tread down since it it now gotten past the point of suggestions and has moved on to examining my character. By the way, the people who looked at this stuff well seasoned bench technicians. Signing off. Link to comment Share on other sites More sharing options...
Searcy Posted March 14, 2012 Share Posted March 14, 2012 Does the noise get louder or quieter when you touch the strings? Link to comment Share on other sites More sharing options...
smalaney Posted March 14, 2012 Author Share Posted March 14, 2012 Does the noise get louder or quieter when you touch the strings? That is the funny part, it stays the same. If it were a simple groundi it would get quieter if I touch the bridge or strings but it does not. The hum is a a consistent volume. Link to comment Share on other sites More sharing options...
Searcy Posted March 14, 2012 Share Posted March 14, 2012 That would explain everything. Guitars are simple devices and don't really have strange, unexplainable problems. If the hum stays the same regardless of whether or not your hands are touching the strings then the wire that grounds the bridge has been pulled lose. Most likely at the post bushing as it is only a friction fit. Your repair man should have suspected this first and been able to find this with a simple continuity test from the output jack nut to the strings. Replacing the pickups will not solve this issue. Only reestablishing the string ground will make the hum go away. While rare, this does happen from time to time and is covered under your warranty. Your repair man should have been able to find and fix this in under an hour instead of putting you through the frustration you are describing. Either he is incompetent or is trying to score himself a set of free BurstBuckers on Gibsons dime. I would take the guitar to a different authorized repair shop have it fixed. Link to comment Share on other sites More sharing options...
Gary Moore Tribute Posted March 14, 2012 Share Posted March 14, 2012 Its seem that the error is a simple grounding, im somewhat surprised that GC would miss such an obvious thing, but their you go... Link to comment Share on other sites More sharing options...
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