Please don't listen to Bobbe on this one (just this one!)

[Jim Simon]

Bobbe was struck by lightning playing at the grand opening of a golf course. Outdoor job in the rain. This has obviously had an effect on his judgement regarding electricity.

He will deny this account as the lightning strike had other determental effects on him which is why he takes massive doses of Levitra.

[Paul Arntson]

What Lynn Oliver said!!!
I taught accredited electrical classes from 1981-1988, and one of my mantras was:
"If you can feel it, it can kill you."

The ability of your body to resist voltage can change literally in a heartbeat. It is called "galvanic skin response". Your skin resistance (the R in E/R=I) can drop from "barely able to feel" the current (1mA) to "unable to let go/ventricular fibrillation" (100mA) if you only break a little sweat or get a little nervous. If you happen to hit a cut on your hand forget it.

Best to use an approved method of signal ground lift and let the power ground stay safe.

[Brad Sarno]

[Paul Arntson]

Good call, Brad!!

A quote from the users manual for the rackmount version on that web page:
"GUITARS - Many guitar players use rack and pedal effects. They can get buzz from ground loops
that these devices create. Use a Hum Eliminator™ to eliminate that buzz. When using two or more
guitar amplifiers, ground loops can form between the amplifiers. Because of the tremendous amounts
of gain in guitar amps, the buzz can get so bad that the amplifiers will actually squeal (especially
with tube amplifiers). Simply run the feed to each amp through one channel of a Hum Eliminator™."

[Mike Schwartzman]

Good Info...I like the HumX idea!

A ground loop is just that- a circle. I think of it as a river that flows back into itself. The path is just "double grounded". The Amp #1 has it's own ground from the wall outlet on the 3rd prong of the power cord. The ground of Amp #1 (on the chassis) goes to the Amp #2 (chassis also) via the connecting instrument cable... then back to the wall supply where Amp #2 has it's own ground on the 3rd prong on it's power cord...double grounded (looped)= Hum (as Brad said like a big antenna). Safe but noisey.

Of course if the house power is not wired correctly all bets are off, and I could easily change my nickname from Slim to "Sparky". Those little outlet testers are less than 10 bucks at most hardware stores. And I always carry one, and I will check out that Hum X, thanks much.

[John Bechtel]

I live in a Mobil~Home. Could it be simply a Low-Voltage Hum? I can't really say that I noticed any Hum out on the job, but; that's been a long time ago also! Usually it was too noisy to tell on the job anyway!

Can someone give me an opinion here?
Here, here!

[Mike Schwartzman]

Well John, Hum can come from many possible sources...some inside and some outside your amps. I guess once you check to see if your home outlet power is wired properly...I guess the 1st question I would ask is...Do all of the various amps hum?...2nd...Do you use single coil pickups on your guitar(s)? 3rd...Are your instrument cables/ power cables in good shape?
Those are just a few things that are easy to check yourself to start eliminating possibilities.

[John Bechtel]

I use a good-quality 6-outlet Power-Strip on a short 3’ cord. All my guitar cords are 10’ standard Peavey Cords. My P/U's on my Derby PSG are Geo.L. 10–1. My Remington P/U's are E–66 and only my Rickenbacker are Sgl. Coil Horseshoe. But, it's not really necessary to have an instrument connected beyond my 1-IN, 2-OUT Vol. Pedal! I'm sure the hum is not caused by the instrument! I do intend to purchase a HUM~X tomorrow and I would like to know if I should plug it into the wall-socket ahead of the Power~Strip or just into the strip, ahead of 1-Amp. (?) I'm also sure I can get the answer to that question from the Dealer! Corner Music, Nashville, TN.

[John Bechtel]

Well, I went to the Dealer and bought a HUM~X, brought it home and tried it on one of my 2-N~112's. Expensive little boogers, but; it did nothing for me that improved on the hum any more than by lifting the ground on one Amp. so; especially because of the expense, I returned it immediately! I guess the slight hum is something I can live with!!

[Dave Mudgett]

Is there really a solution to my Hum-problem? BTW: I live in a Mobil~Home. Could it be simply a Low-Voltage Hum? I can't really say that I noticed any Hum out on the job, but; that's been a long time ago also! Usually it was too noisy to tell on the job anyway!

Sorry I didn't see this earlier - I went away from this thread after my last post.

This is all hypothetical - but if you're living in a mobile home, I suppose it's possible you don't have a true earth ground with a proper grounding rod. It depends on what electrical codes are set up and really enforced for mobile homes - I don't know any specifics about that.

If that's true, it would mean your ground is floating, and there might possibly be some small voltage fluctuations that aren't being shunted to ground. If your ground voltage varies, then any stable voltage measured with respect to ground also varies by that amount, which can add a hum to your sound.

{about HumX) Expensive little boogers, but; it did nothing for me that improved on the hum any more than by lifting the ground on one Amp.

If my hypothesis above is correct, this totally makes sense. The HumX should have the same sonic effect as lifting your ground.

So - if you get the same hum with

1. Amp not lifted, no HumX
2. Amp not lifted, HumX.
3. Amp lifted, no HumX
4. Amp lifted, HumX

Then you may as well go with Door # 1 - Amp not lifted, no HumX. But you might also want to investigate whether or not you have a true earth ground. If you don't, you might want to consider getting one.

[John Bechtel]

Thanks a bunch, Dave! I almost understand everything you said, even though I don't know a whole lot about electricity and it's inherent dangers!

[Alan Harrison]

Like John Bechtel, I bought a HumX a few years ago when I was using two Nashville 112's and it never helped the hum problem anymore than the two pronged adapter. Sure was an expensive little dude, as compared to a two dollar adapter.
I still carry it in my gig bag, I don't know why, since I seldom use two amps anymore.

[Bo Legg]

I hate going to a gig worrying that my life depends on one little wire.
The odds of getting killed because you took out that third wire is about the same as drowning in a kiddie pool. Your biggest risk is traveling to the gig.
So your best bet is to just stay grounded at home.
If Bobbe got struck by lightning, having that third wire hooked up was the least of his worries. It would be like yelling at someone while their drowning in a 1,000 gallons of water. "If you'd a had that dang bucket hangin here like you was supposeto I could save you."

[Mark van Allen]

Respectfully, Bo, tell that to someone who did die in a grounding fault accident.
No one wants to be the statistic that proves the slim chance.
I am curious, do you use the same logic with car seatbelts?
Many years ago I stepped up to play telly and sing on an outdoor festival gig, where the stage was two flatbed trailers side by side. I was plugged into a promoter-provided amp. When I walked up to the mic, all I saw was a blue flash and the next thing I knew I was on my back on the ground behind the 2nd trailer, having flown over the amp backline.
There was an electrician there and he measured 100+ volts between the mic and my guitar cord... there was a ground fault in the main PA system, and the gound plug had been cut off the amp I was plugged into. He told me if the metal trailer had actually been grounded instead of on tires I'd have a lot more than a lip burn.
One chance in a million is just not worth gambling your life.

[ajm]

You don't have to be at a gig to have a problem "just because you took that one little wire out". It could happen at home, too.