# Can Someone Explain The "ground Lift" Feature Found On Some Amps?



## Vinsanitizer

I thought that was a thing of the past, but my new Peavey Mini 20 Head has this 'ground lift' switch. What's it for? I was always under the impression that it could be deadly. I thought they eventually concluded that it was the improper way to eliminate noise or something. I remember flipping the metal switch on an old Fender amp and getting a big shock. I haven't seen these since amps from the 70's.

Thanks.


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## flyinguitars

When two pieces of equip are connected and grounded via separate paths a ground loop can occur. A lift will remove one path and usually help remove the hum.

I have a parker guitar with acoustic piezo style pickup that I use live. The guitar takes a trs (stereo) tip cord that splits into 2 separate 1/4" mono guitar jacks. I plug one (magnetic pickup/regular electric guitar pickup) into my amps and plug the other into a direct box which goes directly into the PA for the acousin signal. My amps are quiet until I plug into the direct box......then they buzz loudly. I have to switch the direct box switch to "ground lift" to get rid of the noise.


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## Vinsanitizer

flyinguitars said:


> When two pieces of equip are connected and grounded via separate paths a ground loop can occur. A lift will remove one path and usually help remove the hum.
> 
> I have a parker guitar with acoustic piezo style pickup that I use live. The guitar takes a trs (stereo) tip cord that splits into 2 separate 1/4" mono guitar jacks. I plug one (magnetic pickup/regular electric guitar pickup) into my amps and plug the other into a direct box which goes directly into the PA for the acousin signal. My amps are quiet until I plug into the direct box......then they buzz loudly. I have to switch the direct box switch to "ground lift" to get rid of the noise.



Yeah, I remember having to do that with DI boxes. Whirlwin I think I was using.


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## The Ozzk

I just don't get why we have to flip a switch. Why not be "lifted" all the time?


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## Vinsanitizer

Well are we still talking about amplifier ground lifts or DI boxes? With DI boxes, depending on your connections, you may need to choose ground/left ground to eliminate noise (if I recall correctly). Back to guitar amps, I don't understand how it's *ever* a good idea to lift (remove) the ground from a circuit, as it's my understanding that doing so could case serious electrical shock when touching both the guitar and other equipment such as microphones.


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## mickeydg5

There is a difference between old ground switches and a ground lift.


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## flyinguitars

Vinsanitizer said:


> Well are we still talking about amplifier ground lifts or DI boxes? With DI boxes, depending on your connections, you may need to choose ground/left ground to eliminate noise (if I recall correctly). Back to guitar amps, I don't understand how it's *ever* a good idea to lift (remove) the ground from a circuit, as it's my understanding that doing so could case serious electrical shock when touching both the guitar and other equipment such as microphones.



Kind-of the same thing. When two devices are connected, lifting the ground removes the additional path to groud. Amp to amp, amp to DI, amp to effects, etc. Having the lift on the amp is a nice option so you don't have to use a 3 to 2 prong power plug adaptor.


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## Vinsanitizer

flyinguitars said:


> Kind-of the same thing. When two devices are connected, lifting the ground removes the additional path to ground. Amp to amp, amp to DI, amp to effects, etc. Having the lift on the amp is a nice option so you don't have to use a 3 to 2 prong power plug adaptor.


Ok, I get that - it's like going from 3 prong to 2 prong. So then the last question is, does it pose any danger of electrical shock to lift the ground?


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## RobLaQuinta

In the USA, the ground and the neutral attach to the same point. They both attach to the grounding bar in the electrical panel. Using a ground lift is not inherently unsafe.


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## mickeydg5

There is more than one type of ground lift design. A ground lift is not an amplifier GROUND SWITCH circuit.


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## flyinguitars

mickeydg5 said:


> There is more than one type of ground lift design. A ground lift is not an amplifier GROUND SWITCH circuit.



Please explain. Is the intention to ultimately interrupt a ground loop?


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## Rich_S

The ground lift switch breaks the ground loop by disconnecting the shield of the direct output from the amp. It leaves the AC safety ground connected from the chassis to the wall outlet. This is the opposite of using a 3-to-2-prong AC adapter, which leaves the shield connected and opens the safety ground to the wall.


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## SonVolt

Electricity makes me feel dumb.


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## Vinsanitizer

I asked the question because my Peavey C20 Mini Head has a "ground lift" feature, which I assumed to be dangerous like the old amps sometimes could be. I just downloaded the manual and this is what it says:

GROUND LIFT Switch:
_Engage this switch if the mix engineer is hearing a hum in the MSDI™ output. This should eliminate the hum by removing the ground loop. Otherwise, leave in the ‘out’ setting, ‘GRND’._

So since this is referring to Peavey's "MSDI™ output" feature (just an XLR direct output to for the house/recording board), I'm gonna assume it's the same as what flyinguitars said about DI boxes. Meaning, at least on this amp, it has nothing to do with any potentially harmful grounding of the amp. It's only for eliminating electrical ground loop noise exactly the same as the lift switch on a DI box. (Basically, Peavey built a DI box into the amp).


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## Frodebro

Vinsanitizer said:


> I asked the question because my Peavey C20 Mini Head has a "ground lift" feature, which I assumed to be dangerous like the old amps sometimes could be. I just downloaded the manual and this is what it says:
> 
> GROUND LIFT Switch:
> _Engage this switch if the mix engineer is hearing a hum in the MSDI™ output. This should eliminate the hum by removing the ground loop. Otherwise, leave in the ‘out’ setting, ‘GRND’._
> 
> So since this is referring to Peavey's "MSDI™ output" feature (just an XLR direct output to for the house/recording board), I'm gonna assume it's the same as what flyinguitars said about DI boxes. Meaning, at least on this amp, it has nothing to do with any potentially harmful grounding of the amp. It's only for eliminating electrical ground loop noise exactly the same as the lift switch on a DI box. (Basically, Peavey built a DI box into the amp).



Correct-that particular ground lift is specifically for the XLR output and has nothing to do with the mains ground. The Kemper has a bunch of inputs and outputs on the rear panel, and almost all of them have their own ground lift switches.


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## Jethro Rocker

My Peavey 6505 MH has one as well, as does my Zoom G3 at the XLR out. To remove ground hum at that point, not AC ground.
How do you like the little 20??


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## Vinsanitizer

Frodebro said:


> Correct-that particular ground lift is specifically for the XLR output and has nothing to do with the mains ground. The Kemper has a bunch of inputs and outputs on the rear panel, and almost all of them have their own ground lift switches.



Right. I didn't have a copy of the manual and didn't even consider referencing it because it didn't occur to me that the switch was associated with the XLR out. I've never seen an XLR out on an amp with a ground lift. Smart idea though. I assumed it was the same type of ground switch that, as far as I knew, became obsolete probably not too long after the advent of grounded AC plugs. I think the NEC started requiring 3-pronged AC home wiring in the late 60's? Electrical appliance manufacturers probably weren't required to change from the 2-prong plug design until a while later, because appliances with grounded plugs wouldn't be compatible in buildings that didn't have upgraded outlets wouldn't be compatible. And even after, whenever it was necessary, I recall people pulling the ground prong off the plugs in order to use newer appliances. Anyway, some amps like Fenders and a few old Gibsons I remember had a metal toggle switch for lifting the grounding on the amps? Maybe some were also reverse polarity? THAT was an electrical hazard that I still don't understand, but I remember getting shocked by those things. I also remember getting my lips toasted by a microphone a couple times.


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## Vinsanitizer

Jethro Rocker said:


> My Peavey 6505 MH has one as well, as does my Zoom G3 at the XLR out. To remove ground hum at that point, not AC ground.
> How do you like the little 20??



I like a lot about the 20, especially running it into an Orange 1x12 with a V30:

It's a good Marshally sound
It has reverb
It has 2 channels
I really like the footswitchable volume boost function, because it allows me to boost solos. This means I can use my guitar's volume control to control the amount of gain, and then wind it up while simultaneously hitting the boost for solos.
It's small, light, portable and cheap
It's loud enough to gig with (and even if it ever isn't, I'll stick a flat preamp in the FX loop to get a litle more volume).
It looks cool on the Orange cab
It just has a ton of useful features like tube fail LED's, XLR out, speaker mute, headphone out, 20/5/1 watt selectable power. I mean what's not to like?

How do you like your 6505MH? I'm considering getting one of those too, I like the sound and features of them as well. I mean just the amount of control from the front panel is amazing: rhythm volume & gain, lead volume & gain, footswitchable boost, reverb, resonance, presence - HUGE bang for the buck.


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## mickeydg5

flyinguitars said:


> Please explain. Is the intention to ultimately interrupt a ground loop?


Anything that raises a components reference from chassis ground as a reference is a ground lift. It creates more than one reference plane.
I wish I could find a simple or decent schematic to show something to look at here. But nothing with ground lifts really has readily available schematics. Anyway a ground lift can be a plain separation from chassis ground or it can be a slight raise in reference from ground. The switch would toggle between lets say the chassis ground and the lifted reference. The lifted reference could be ten, twenty or forty something ohms or maybe even just a capacitor or a combination of both. You can look at some amplifiers and see a separation of references using such components. All that is needed to make them switchable is a toggle with option of ground lift circuit or direct ground.

This schematic has a 100nF capacitor/10 ohm resistor ground lift circuit.


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## Vinsanitizer




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## mickeydg5

You made it white. Tehank you.


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## Vinsanitizer

mickeydg5 said:


> You made it white. Tehank you.


Tehank _you_.


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## Jethro Rocker

I really like the 6505. Similar functions to the Classic, 3 channels if you count the Crunch boost feature on Ch1. Tons o gain, I found it needs lots of Pres setting to bring it alive. The "clean" sounds very raunchy with gain pinned and left in Clean mode. So many footswitchable functions!! Nice little amp through a Mesa V30 1x12. My 6101 has a ground lift on the XLR as well.


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## The Ozzk

BTW Vin, how's your band coming along?  Inc.


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## Vinsanitizer

The Ozzk said:


> BTW Vin, how's your band coming along?  Inc.



We were doing pretty good until about 4-5 weeks ago - too many summer events, vacations and company meetings/traveling for each of us. Summer's always been a tough time to be in a band, at least for me. We're picking back up next week though, and at this point we've got about 32 or 33 songs in the bag. I think we're trying to hit 45 and then rehearse the piss out of them, so we expect to start gigging regularly by late this year. Last song we added is "The Boys Are Back In Town" off Lizzy's Live and Dangerous. Man, what a fun song to play all those dual solos with 2 guitar players. That's my forté right there.  The band isn't very much _my_ band per se, I've been happy letting one of the other guys take the lead because I've got too much other stuff going on to be much of a leader. So it's ended up being a lot more toward the lighter side of classic rock where I prefer the harder side. But, it's an easy gig and I don't have to operate at too demanding a performance level.


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## Coronado

SonVolt said:


> Electricity makes me feel dumb.



I heard that man. My eyes glaze over as I try my best to follow along with those schematics. I nod and smile like I totally get it - much like this other dummy...


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## mickeydg5

The funny thing is if it were not for electricity you would feel nothing at all.


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## Vinsanitizer

mickeydg5 said:


> The funny thing is if it were not for electricity you would feel nothing at all.


Yeah wow - what's with electricaltricity, man? I know I'm electrical because when I touch people in the winter times we both get a shock.


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## flyinguitars

mickeydg5 said:


> Anything that raises a components reference from chassis ground as a reference is a ground lift. It creates more than one reference plane.
> I wish I could find a simple or decent schematic to show something to look at here. But nothing with ground lifts really has readily available schematics. Anyway a ground lift can be a plain separation from chassis ground or it can be a slight raise in reference from ground. The switch would toggle between lets say the chassis ground and the lifted reference. The lifted reference could be ten, twenty or forty something ohms or maybe even just a capacitor or a combination of both. You can look at some amplifiers and see a separation of references using such components. All that is needed to make them switchable is a toggle with option of ground lift circuit or direct ground.
> 
> This schematic has a 100nF capacitor/10 ohm resistor ground lift circuit.



Thanks!
Since I use a multi amp setup, trs cable from 1 of my guitars to both amps and pa, an ac wireless for the other guitars and sometimes an AC powered pedal, I always have a ground hum until I start lifting...lol. Sometimes I have to lift at the amp plug....sometimes both amps...lol we try to keep a supply of 3-2 prong adaptors in our gear cases, but in a pinch, I've snapped the amp ground post of of the plug. I never really thought about the difference of a amp chassis ground. But as a habit always lifted the amp at the outlet as a last option.


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## DaDoc

Can't really explain it, but I do know it has to do with eliminating hum..I had a tech install a grounded plug in my '73 JMP, and while he was at it he took out the "death cap" and made the polarity switch a ground lift..I never use it though.

I like my amps to be earthed, it's one of the few quibbles I have with vintage amps..


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## Vinsanitizer

Grounded = US
Earthed = UK


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## mickeydg5

We earth here in the US too.


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## Vinsanitizer

mickeydg5 said:


> We earth here in the US too.


Yes, but we also ground. Have you never been grounded before?


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## mickeydg5

We called it _punished_.


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## Vinsanitizer

mickeydg5 said:


> We called it _punished_.


Ok, I can understand maybe some families said that. But mine always told me to go to my room because I was _grounded_, not punished.
Man, cultural (and electrical) diversity's so hard to keep track of these days, I'm tellin' ya.


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## mickeydg5

Yes cultural diversity. That is what it is.
If my parents would have told me I was grounded then I would have thrown away my pilots license and sold my plane.


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## DaDoc

I just like the way "earthed" sounds..Kinda organic. The Brits do have some cool expressions!

And "grounded" does sound a bit like punishment.


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## mickeydg5

I kind of think ground and earth are the same. Is it not?

That is unless you live on the Moon, Mars or some other celestial body.

But then you would still say ground and maybe mars instead. "Say you Brit (being from Britian on Earth), do you have that thing marsed correctly?" That just sounds ridiculous.


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## Vinsanitizer

mickeydg5 said:


> I kind of think ground and earth are the same. Is it not?
> 
> That is unless you live on the Moon, Mars or some other celestial body.
> 
> But then you would still say ground and maybe mars instead. "Say you Brit (being from Britian on Earth), do you have that thing marsed correctly?" That just sounds ridiculous.


Yeah - they're the same thing. We're just having fun with the terminology. I've always heard "grounded", unless I was reading a Marshall brochure or instruction manual where they say "earthed". I think I'm kinda preferring _earthed_. It sounds a wee bit more sophisticalcated.


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## The Ozzk

When I hear the word "earthed" , like, I kinda crave granola  Inc.


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## mickeydg5

I am just having fun too, earthed to the ground, grounded to earth or not.


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## Vinsanitizer

Grourthed?

Anyone? Bueller? ...Bueller?


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