Should I use a polarity switch?

[Silvio55]

Hi folks, I'm seriously considering adding a polarity/ground switch to my amp, I live in Argentina, and sadly, 99% of the places we do gigs with my band donīt have earthed outlets. I always carry a long cable and a screwdriver or something to make an earth conection when we play outdoors, I attach one end of the cable to the third lug of the mains plug and the other to the screwdriver and stick the screwdriver to the ground, but when we play indoors I can rarely do that.
Without an earth conection my amp (all of them in fact) can get very noisy, specially with single coils, the last gig I couldn't even use my single coil neck pickup.
What I want to know is if adding this switch, that puts a cap between the chassis and one mains line would help me with this noise issues.
Thanks!

[g1]

I don't think a polarity switch will help with noise that is being picked up by single-coils.
But whatever you decide, if you go with a polarity switch be sure to use a class-Y capacitor.

[olddawg]

It's not that uncommon to have ungrounded outlets (even with brand new receptacles installed) even in the U.S.A. Especially in old buildings. A ground lift adapter will do pretty much the same thing as a polarity switch. If you put one on a power strip and plug all your gear into it then you will have the same reference for everything and all the grounds connected together. If there is a cold water pipe available you can clamp your "long wire" to to it and then connect it to the ground lug on the ground lift adapter. The pickup buzz you get is most likely from light dimmers or flourescent lighting. I play a club that is notorious for it because of the lights on the gas station next door.

[tedmich]

What would Juan say?
a ton were he here...

[Silvio55]

Thanks! The main problem I have in most indoor gigs, is that there's never a water pipe or something like that to make a ground conection near the stage, I can't have the wire running throu the bathroom or the kitchen in those places, it would be a mess!!
I know that having a ground conection is better than the polarity switch, but sometimes I just can't do it, and I'm getting frustrated by the buzzing noise I get.
I didn't knew about those Y-class caps, I'll see if I can find one here.

[olddawg]

Do you know what a power strip and a ground lift adapter are and how a ground lift adapter is used? Doing what I said earlier, even without an earth ground, will probably not stop your buzz.... But I might keep you from getting a bad shock.

[Silvio55]

Yes, I always use power strips, and the ground lift adapter should be this:

Never used one, and never seen one around here but it's the same thing as I do with a cable attached to the third lug of the mains plug, either in the amp or the power strip where I plug the amp, or it isn't?
What's the benefit of using the ground lift adapter if you don't conect it to ground?

[olddawg]

Yes.. That is a ground lift adapter. If you plug all of your 3 prong power cords for all your gear (amps, PA, etc) into the same power strip, they wil all have the same wiring and ground reference. Then you can put the ground lift adapter on the power strip cable. If you need to reverse the wiring (for the ubiquitous reverse wired receptacle or whatever) you just plug it in reversed. No need for a ground reverse switch. I have 4 of them in my kit. I'm always having to float something to get rid of a ground loop hum (usually a DI situation) which sometimes happens when all your chassis grounds are connected together even if everything is to code. There is no perfect situation. I think Juan is in Argentina or thereabouts. He can probably advise you on local specifics.

[Silvio55]

Now I get it olddawg!
Maybe I expressed myself wrong, I'm talking about the switch that connects a cap between the chassis and either of the mains line, like the old Fender tweeds, not the polarity switch that inverses the mains lines. I have 3 to 2 lugs adaptors, I have used them for reversing the polarity and sometimes they have helped a bit, most of the time didn't.