#1
So I've been dealing with this ground problem for quite some time now. Just one question: My amplifier (Roland Cube 30x) has a two pronged cable that connects to electricity. There is no ground prong. Could it be possible that this is why my amplifier makes a buzzing noise?

Again, when I touch the strings of my guitar the buzz reduces. But when no input cable is attached there is no hum.

So, back to the question, is it a problem that I have no ground prong for my cable? I've done some research and it doesn't seem like anybody else has a humming problem with the roland cube, but I'd just like to know. Also, if you don't know the answer to my question, please just tell me if your amplifier has two prongs or three prongs.

Sorry, if this is a dumb question, but I don't know much about wiring and such.
#2
If it has no ground prong, it'll just be grounded through the neutral pin (larger plug tip). Or did it used to have a ground pin and now there isn't one?

Does it hum when you plug in an instrument cable that isn't connected to anything?
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Feel free to express yours so I can make an informed judgement about how stupid you are.
#3
Yes, it does hum when I plug in the instrument cable. And no, there was never a ground plug. I think my problem might lie in the actual cable. One more question, how much resistance should there be between the strings of my guitar and the pots?
#4
Since your bridge will be grounded, if you test for continuity between the strings and the pots, the multimeter should beep.
Everyone is entitled to an opinion.

Feel free to express yours so I can make an informed judgement about how stupid you are.
#5
between strings and the pot, there should be 0 ohm resistance.

and also there should be 0 ohm between ur strings and ur lost ground prong as well.
Call me "Shot".

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Custom Hand-wired Amplifiers and Effect Pedals.

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#6
Can I add to this?
Iv also got a similar setup. My ground plug is broke on the extension chord I use.

Now the other day I was getting numb fingers and what I can describe as a 9 volt tingle in my finger when touching metal(strings, screws in my amp, bridge, ect). Is this dangerous and what should I do to make sure I dont have to much hum and or get electrocuted.
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#7
there isn't even a ground switch for your amplifier. you could die from this... it was even in csi. the bass player's amp's ground prong was broken, so he got electrocuted. so maybe you should invest in another extension cord? if you even need extension...
Call me "Shot".

ShotRod Guitar Works

Custom Hand-wired Amplifiers and Effect Pedals.

Est. 2007


Source to everything I say about Guitars, Pedals, and Amplifiers: I make them.


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#8
Quote by ECistheBest
there isn't even a ground switch for your amplifier. you could die from this... it was even in csi. the bass player's amp's ground prong was broken, so he got electrocuted. so maybe you should invest in another extension cord? if you even need extension...

O man iv got one custom made from in wall wiring, that should do the trick. Im just wondering because this just started happening, iv been playing like this for a little less then a year. The only thing thats changed is I added another surge thats being used to give the other guitar player more movement. Basically im running an extension chord to a surge strip, and I run my amp, my friends devilles and our little PA setup off it. Whats a ground switch used for and how come amps come without them if its as important as it sounds?
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Fender Stratocaster MIM - 04
Fender Mustang - 04
Taylor 214ce - 10
Last edited by teamhex at Jun 2, 2010,
#9
ground switch is obsolete since the '70s. real old amps only had two prongs, and needed one prong to be the ground. amps these days dont have one because the ground prong (the third prong) replaced it, and it is much safer.
Call me "Shot".

ShotRod Guitar Works

Custom Hand-wired Amplifiers and Effect Pedals.

Est. 2007


Source to everything I say about Guitars, Pedals, and Amplifiers: I make them.


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#10
Quote by ECistheBest
ground switch is obsolete since the '70s. real old amps only had two prongs, and needed one prong to be the ground. amps these days dont have one because the ground prong (the third prong) replaced it, and it is much safer.


Ahh cool man. Well i guess ill make a 3 pronged extension cable. Thanks for the advice.
Gibson Les Paul Traditional - 11
Fender Stratocaster MIM - 04
Fender Mustang - 04
Taylor 214ce - 10
#11
As I said before, if it doesn't have a ground prong, the neutral is the ground just like those old devices.

The reason it was unsafe was also the reason it was fun - because the old outlets were polarity non-specific, it was possible to reverse the plug and feed the neutral instead of the line. Since the neutral was also grounded to the chassis, all grounded metal parts became live when you did this. In the case of amps, this includes the strings as the bridge and pots are part of the amp's ground.

This allowed for quite a bit of fun, though. My dad had an old beer fridge in the basement that was like this and whenever he wasn't using it, he'd plug it in backwards.

We'd go down to steal beer and get shocked. It was a pretty effective deterrent. Really the only way it would kill you is if you got super sweaty or were soaking wet from the pool or something and grabbed it, but it'd sure make your arm jump.

The old amps usually had a polarity switch though so you could plug it in and switch the ground so it was proper.

At any rate, that's pretty irrelevant these days, since even two prong plugs are polarity-specific. The line side is 2/3 the size of the neutral side, which will not fit in the socket in reversed configuration.

Besides, the ground plug and the neutral are the same damn thing when it gets back to the panel because unless you live out in the sticks the circuit isn't properly earthed until it reaches the transformer at the line service.
Everyone is entitled to an opinion.

Feel free to express yours so I can make an informed judgement about how stupid you are.