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Earth/Ground Lift

Fábio Duarte

Fábio Duarte

Guest
Apr 17, 2014
100
6
33
Portugal
#1
Few Questions

- What difference does it make to the amp, and me obviously, using or not the 'Earth Lift'?

- Should I keep it ON always, or does it will damage my amp?

- For instance. My house don't have an 'Earth' wire. Can I use my amp? With or withou the 'Earth Lift' ON?

Thanks!!
 
#2
The ground lift should only apply to the DI out on your amplifier when it is connected to a mixer, usually in a live situation. The setting depends on which provides a cleaner signal.
All amplifiers should have a 3 prong plug for safety. Never remove the ground prong!
Even older houses have to have a ground reference somewhere. I would recommend that you talk with an electrician to find the best, safest solution for your home.
 
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#3
The switch selects the reference ground for the DI : your amp or whatever is plugged at the other end of the XLR.
Use the position that produces the less hum.

It is not related in any way with the ground protection of your amp.
Properly grounded buildings save lives daily. It should be a top priority in the improvement of your house.
Actually you shouldn't even use a washing machine or refrigerator without grounding, they are potentially fatal hazards.
 
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#8
Thanks for the answers, but you did not answered my questions.. So, what difference does it make to my amp being with or without the 'Earth Lift' ON?
And to me?

And at my house, I have not ground wired jacks to plug in my amp. Should I use or not the earth lift switch ON?
 
#10
Jazz Ad said:
Answers were provided several times to each questions.
Click to expand...
Sorry, my bad.. Bad sunday morning... So, let me see if I actually learned something today.

The "Earth/Ground Lift" only should be used, or only makes difference, when I have a DI (or something 'XLR else') on the other end of my "Balanced DI Output". So, anywhere I use my amp and I don't use the DI Ouptut of my amp I don't have to worry about the 'Earth Lift' switch. Right or wrong?
 
#11
Actually, while in modern amps with a DI, the ground lift refers to the DI Output, there were many older amps, like the Ampeg B15 that have a switch to remove the chassis ground.
Having the chassis grounded, especially on a tube amp, is always a good idea to prevent the possibility of a shock hazard. If you are plugging into an ungrounded outlet, it's not going to make any difference, the hazard will exist regardless.
But because you (the OP) didn't mention what amp it was, there is no way to determine what the switch in question, is for the DI or chassis ground.
 
#12
Agree with @popgadget in that older amps that didn't have grounded wall plugs usually had a ground switch to ensure you don't zap yourself whenever you touch metal while playing. I don't know if that is referenced as a "ground lift" on the older amps but will tell you it's not pleasant if you had it off while stepping up to sing and your lips touch the microphone.
 
#13
Let's see if we can help a little more.

Can you tell us the exact brand and model of amp you have?

Can you take a picture of the plug on your amp and the outlet you will plug it into and post those pictures here?

Everything we tell you will be just a guess until we can get more specific. Thank you.
 
#14
popgadget said:
Actually, while in modern amps with a DI, the ground lift refers to the DI Output, there were many older amps, like the Ampeg B15 that have a switch to remove the chassis ground.
Having the chassis grounded, especially on a tube amp, is always a good idea to prevent the possibility of a shock hazard. If you are plugging into an ungrounded outlet, it's not going to make any difference, the hazard will exist regardless.
But because you (the OP) didn't mention what amp it was, there is no way to determine what the switch in question, is for the DI or chassis ground.
Click to expand...

The ground switch on old amps doesn't remove the chassis ground it changes the polarity of the line filter connection from hot to neutral. The reason you can get shocked on old amps with the "death cap" intact is that if the cap fails you're potentially putting live voltage on the chassis which would pass through any chassis ground connection (like the ground reference of the input jacks which are connected to your instrument cable and bass). There's a good write up in the portaflex wiki pages.
 
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#15
popgadget said:
Actually, while in modern amps with a DI, the ground lift refers to the DI Output, there were many older amps, like the Ampeg B15 that have a switch to remove the chassis ground.
Having the chassis grounded, especially on a tube amp, is always a good idea to prevent the possibility of a shock hazard. If you are plugging into an ungrounded outlet, it's not going to make any difference, the hazard will exist regardless.
But because you (the OP) didn't mention what amp it was, there is no way to determine what the switch in question, is for the DI or chassis ground.
Click to expand...

Trace Elliot GP7SM 200 watts combo. In my signature
 

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#16
Fábio Duarte said:
Trace Elliot GP7SM 200 watts combo. In my signature
Click to expand...

Strangely enough, of all the audio gear I've owned, my TE preamp was the only component which required ground (earth) lift to "play nicely" with the other rackmount gear. If ignored, there was a nasty hum which was probably caused by a ground loop / conflict. Pic below. The second rocker switch from the left is the earth lift. I pushed it to the right to select the "/" configuration.

TEBackTop_zpsb47d548b.jpg


Here's the blurb / description from the manual as to how it works:

"Ground lift A GROUND LIFT switch is provided to lift the mains ground from the signal circuits and prevent a ground loop being formed between the pre amp and the power amp."

Riis
 
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#17
Not having three conductor power line at home could make the amp noisier but it is not unsafe for the amp to use it this way. The third conductor is there for your safety, it blows the fuse or turns off the circuit breaker in the event that something shorts and puts the line voltage onto the chassis.

If you touch another piece of equipment, such as the recording gear, while touching your strings or the amp, you could get a shock. The solution is to reverse one of the plugs.
 

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