Fender tube amp ground hum

Discussion in 'Amp Tech Center' started by Craig Williams, Sep 29, 2020.

  1. Craig Williams

    Craig Williams Tele-Meister

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    Living in Thailand and power supply rubbish. Getting a lot of ground hum on my 3 amps. All newer amps, Fender Super Champ XD, Laney VC30 and Fender rumble bass amp. All my guitars are pretty good, a couple even shielded, leads good. Its the hum where you take your hands off the strings and it gets worse. I read somewhere you need to use 3 pin plugs but that doesn't seem to make any difference. In any case earthing here in homes pretty sketchy, sometime non existant. I have about 6 guitars all doing the same thing, single coil and humbuckers so its not a guitar problem.

    Any other way to get around it? I have had hum from lights etc before but this is a bit worse than that and we don't have any flouro fittings in the house. Proximity to TV's, computers a problem?
     
  2. Jon Snell

    Jon Snell Tele-Holic

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    If the hum varies with the proximity of the guitar and angle towards other equipment, it is magnetic pickup but it sounds like an earthing issue.
    Assuming it is an earthing issue, check there is good continuity between the guitar jack screen and the strings. If that is good then you need to earth the equipment.
    I presume there is no Electrical Standards for home wiring where you live, otherwise it can be fixed quite simply by connecting the three core mains sockets correctly.
     
  3. MLJ1

    MLJ1 TDPRI Member

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    If you have Cable for TV there, it is usually a good grounding source. It is normally grounded to a rod outside your home, that goes into the ground itself, hence the term "ground". Another way would to check be to run a wire from the ground on your amps powerstrip to the wire wrapped around the cable. Strip back the cable, or just try touching the ground (just the ground, don;t electrocute yourself by touching the "hot inner wire" to the cable's nut and see if the ground noise goes away. Also, if you have power supply(s) for pedals, they can be bad, giving you a ground fault.
     
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  4. tubegeek

    tubegeek Friend of Leo's

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    Easy enough to verify proper grounding: measure resistance between the outer shell of your (plugged-in) instrument cable and any metal water pipe that is buried in the earth at some point. Should be very very low ohms, ideally less than a couple of ohms.

    It's possible to have a ground connection added to your system if none exists, and that would be a safety measure that would be worth doing in its own right.
     
  5. Wally

    Wally Telefied Ad Free Member

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    I do not assess amplifier noise with a guitar plagued in. Do these amps hum with nothing plugged in?

    “It’s the hum where you take your hands off the strings and it gets worse.” Just to be clear.... the hum that occurs when you are not making contact with a ground point on the guitar is natural. If this is your problem, you do not have a problem...other than not turning your volume to zero when you are not going to be touching a ground point...strings, bridge, etc.
     
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  6. EddieLocrian

    EddieLocrian Tele-Afflicted

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    Dimmer switches are Bad for guitars/amps.
     
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  7. Craig Williams

    Craig Williams Tele-Meister

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    Ill do a bit more testing tomorrow and see if I can eliminate a few things. We don't have steel water pipes here. No dimmers. I am in a rented house so I wont be doing any expensive additions. I wont go into specifics about electrical and water installations in Thailand but suffice to say horrendous. I do have cable TV, will check tomorrow if grounded anywhere. I do believe in Thailand even the Power authorities don't put much stock in MEN earthing.
     
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  8. tubegeek

    tubegeek Friend of Leo's

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    Yeah, pvc pipe or tubing in the system kinda invalidates what I said. Are the outlets 3-wire at least? If there's continuity on the "ground" wires back to the box then you may be able to add a ground rod for proper earthing as a retrofit. If not, then at the very least you'll have to open up the outlets and see if each ground wire even exists in the cable that was used. Pain in the tuchus.
     
  9. Boreas

    Boreas Tele-Afflicted Silver Supporter

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    You could try a power conditioner - preferably on a dedicated circuit. Many audiophiles and AV enthusiasts use them to clean the power source to eliminate peaks and troughs of power as well as minimizing spurious signals that may be present in the line. Then find a good ground. Then track down RF interference from appliances and lighting.
     
  10. Craig Williams

    Craig Williams Tele-Meister

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    Before I start pulling stuff apart....I'll ask another question. Apart from safety reasons is it neccesary to have an earth connected to your amplifier? For eg will it definitely hum if no earth at the outlet or a 2 pin plug is used, or only sometimes or will be a bit worse with no earth?

    Reason I ask is one amp I have, a solid state sort of PA / Keyboard amp I bought new and it definitely only came with a 2 pin plug. Funnily enough though it is the only one that doesn't hum
     
  11. Boreas

    Boreas Tele-Afflicted Silver Supporter

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    One way to find out. You could try a cheap 3>2 prong (non-grounded) adapter.
     
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  12. tubegeek

    tubegeek Friend of Leo's

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    "Apart from safety reasons" is a lot different question with respect to tube amps than to solid-state amps. It's impossible to get a 350-volt shock from a solid state amp. And certainly it is the case that more modern gear can be quieter.

    Modern equipment with two prong plugs can be assumed to have been designed with a certain level of safety precautions. Old 2-prong tube gear had some safety issues (death cap, no "double insulated" requirement) that make the use of a properly grounded 3 prong plug very important, and that relies on properly grounded outlets for safety and (sometimes) low noise.

    My opinion: an electric guitar discussion board has its limits for the purpose of researching the safety of the electrical hookup in a country with a loose enforcement of electrical and construction code.

    Whenever I discuss this stuff with anyone I'm mindful of these things: I'm a sorta-knowledgeable amateur, not an electrician; I do my own electrics in my own house and I always choose to stay on the side of caution; I'd REALLY hate to give any kind of advice that could get anyone hurt or killed.
     
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  13. Craig Williams

    Craig Williams Tele-Meister

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    Problem solved. Changed the polarity around. Maybe a slight difference but still buzzy. Moved the guitar around, tried a few other guitars and leads no difference. Tried a three pin jug cord in the amp. Then I realized the 4 outlet extension board I am plugging into has a two pin plug on it lol. Took the amp straight to the outlet 3 pin jug cord and good as gold. Need to get me some 3 pin plugs [​IMG]



    Funny because I read on a few sites last night mains earthing makes no difference to guitar hum. It's a grounding issue inside the electronics.



    Thanks all for your help
     
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  14. tubegeek

    tubegeek Friend of Leo's

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    Safer and quieter - a win/win.
     
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  15. Boreas

    Boreas Tele-Afflicted Silver Supporter

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    Jeezus, what kink of extension board is that?? It has 3-prong outlets yet it has an ungrounded cord? Bizarre - and stupid - unless I am misunderstanding your description.
     
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  16. Craig Williams

    Craig Williams Tele-Meister

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    I am living in Thailand and anything goes. I have plenty of power boards with 3 prong socket outlets but only 2 wire cable and 2 pin plug, came from the shop like that. If you knew Thailand its not about the safety, its about duh....This outlet will be good, I can plug 2 and 3 pin sockets into it. I have bought many appliances here also that should have had a three pin plug....well they did but it was the European Shuko plugs. No earth pin but a strip of metal to connect with the outlet. Unfortunately Thailand doesn't use Shuko outlets so there is no earth connection on a steel framed appliance. I've never worried about it too much because if you could see the suicidal way they drive the last on your list of safety priorities is electrical safety.

    Last home I had here all the points were earthed, but when you looked in the main Circuit breaker board all the earth wires were just twisted together by hand (not in a connector) and no earth wire going to an external earth rod / source. Most homes have the bar minimum of outlets too so most homes have power boards everywhere. I have seen cables run to a light 5 meters, with 4 bits of cable joined together (again twisted by hand not even taped). Its mad. Mind you I have never seen a house fire here nor have I ever seen a firetruck on the way to a fire. Could be lots of people electrocuted going in ambulances though o_O:lol:

    There are no qualifications needed to do wiring here
     
    Last edited: Oct 1, 2020
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  17. Boreas

    Boreas Tele-Afflicted Silver Supporter

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    Interesting! I guess the power strips there are more like a Swiss army knife - capable of doing allotta things poorly...
     
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