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Guitar player question....ground hum


Kenny202

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Hope ok to post here, don't really have a musicians area. Having a problem at home with ground noise from my amplifiers. We don't have flourescent lights. All of the guitars and all of the amps are doing it so not just a badly shielded guitar. Leads are good. I read somewhere you need to use 3 pin plugs but I wouldn't be surprised if there was even a proper main earth joint outside.

 

Any of you guys found a way to overcome it here? I mean lets face it the power supply probably rubbish and unregulated. is there a power filter or something they use to reduce the hum?

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In some recording studios I've worked in we ran the house mains first through an Isolating Transformer to decouple it from Earth-Ground to avoid ground-loop noise, conditioned it by running in through some noise filters to eliminate AC hum, then made sure ALL INTERCONNECTED EQUIPMENT used only that AC power source.

 

Having shielded cable helps. Mics should ideally use 3-pin XLR connections.

 

But if your environment is already filled with EMI or RFI sources then you'll be fighting an uphill unwinnable battle trying to isolate it without compromising on 'the sound'. 

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Its only the guitars. Don't use mics, but as you said and only occurred to me while writing this post I am probably only 2 or 3 meters away from the TV where I sit, and about 3 meters away from the computer screen. But by the hum reducing when you touch the strings doesn't that indicate a ground problem?

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Try reversing the plug in the wall socket.  My old (late 60's) Fender amp has a 2-wire AC power cord along with a "ground switch" that I believe reverses the polarity of the AC power cord in order to reduce hum.  This should work, provided that your house wiring isn't wonky - which is highly likely.

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1 minute ago, DrDave said:

Try reversing the plug in the wall socket.  My old (late 60's) Fender amp has a 2-wire AC power cord along with a "ground switch" that I believe reverses the polarity of the AC power cord in order to reduce hum.  This should work, provided that your house wiring isn't wonky - which is highly likely.

If anything I would say VERY likely. Wasn't as bad as the last house I had would get electric shocks off everything. There was no earthing at all

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7 minutes ago, Kenny202 said:

I am probably only 2 or 3 meters away from the TV where I sit, and about 3 meters away from the computer screen. But by the hum reducing when you touch the strings doesn't that indicate a ground problem?

 

Try unplugging BOTH and see if that help eliminate some of the hum issue.

 

Amplifiers aren't picky about what they're amplifying. A google search for guitar hum when not touching strings will send you down the rabbit hole, but might e helpful.

 

The first highlighted article covers some interesting points.

 

Minimising Noise In Electric Guitar Rigs
Sound on Sound | Guitar Technology | By Dave Lockwood | Published 2006

 

A friend eventually went to using a battery-powered Amp setup with short as possible patch cords because there were just too many issues to solve.

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8 minutes ago, RichCor said:

 

Try unplugging BOTH and see if that help eliminate some of the hum issue.

 

Amplifiers aren't picky about what they're amplifying. A google search for guitar hum when not touching strings will send you down the rabbit hole, but might e helpful.

 

The first highlighted article covers some interesting points.

 

Minimising Noise In Electric Guitar Rigs
Sound on Sound | Guitar Technology | By Dave Lockwood | Published 2006

 

A friend eventually went to using a battery-powered Amp setup with short as possible patch cords because there were just too many issues to solve.

Thanks so much for your effort mate. 

I'll ask another question. Apart from safety reasons is it absolutely necessary 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 some amps, or 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 here and it definitely only came with a 2 pin plug. Funnily enough though it is the only one that doesn't hum. The other 3 do. 2 are valve amps to so I guess they are more prone to hum 
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13 minutes ago, Kenny202 said:

Thanks so much for your effort mate. 

I'll ask another question. Apart from safety reasons is it absolutely necessary 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 some amps, or 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 here and it definitely only came with a 2 pin plug. Funnily enough though it is the only one that doesn't hum. The other 3 do. 2 are valve amps to so I guess they are more prone to hum 

Is it possible that  your mains power supply is  "under  voltage" ? Noting that  you say it is the  valve amps that hum  suggest  that because  valve  amps are trimmed output  while  solid state  are  power on output demand.

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13 minutes ago, Dumbastheycome said:

Is it possible that  your mains power supply is  "under  voltage" ? Noting that  you say it is the  valve amps that hum  suggest  that because  valve  amps are trimmed output  while  solid state  are  power on output demand.

No, its not tube hum. I have 2 tube amps and a solid state bass amp and they are pretty much the same

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Just now, Yellowtail said:

You might ask the mods to move it to the electric forum.

 

If you're in Bangkok, the quality of the power is good. It might be cr*p in your building in the greater Bangkok area is fine. 

It is a guitar player specific question and I don't live on Bangkok. I have asked the question in a different way re home earthing in the electrical forum.

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47 minutes ago, Rookiescot said:

Try un plugin your wifi, TV and anything else which will emit radio waves.  

Its true. Strange enough, i found it to be the fridge, in one place i lived.

It would mess with my old tuner also as the tuner in the open mode would always be stuck around G or Gflat.

 

Of course, I finally realised what was going on when the hum would suddenly stop and realised that coincided with the fridge clicking out.

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Yes, good as gold now. Changed all my plugs over to 3 pin. It appears the home earthing is good. By the way, I was always having trouble with the multi outlet power boards here. Even the expensive ones. What I do now if cut the lead off the broken one and go to local electrical store and can just buy the outlet board itself, no cord for about 100 baht. The ones I get a much more heavy duty, no switches etc to break and seem to last forever. Really good strong plug connections. Will accept different plug configurations. One in the photo only has one 3 pin outlet but can buy with 2 or 3. Just attach the old cable to it and good to go. I think they might be even made for tradies. The fancy 300 baht ones you buy switches always seem to fail, plug connections really loose, particularly if you have a charger or something heavier plugged in. 

IMG20201001055808.jpg

IMG20201001055814.jpg

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9 hours ago, Rou222 said:

I should try this as well, cause I'm done hearing the radio while the amp is on  

Thanks for the thread!  

Buzz instantly went away. Just make sure your power board has a 3 wire cable / 3 pin plug and your house is actually earthed. I have had other homes here had 2 pin and earth sockets but the earth wires in the home weren't actually attached to an earth outside. Funnily enough there was an earth rod installed specifically for the shower heater.....And a live power outlet mounted under the arm of the shower head.....I shirt you not! I guess someone liked to dry their hair in the shower lol

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