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shock!

Started by Mike_Sims, March 14, 2011, 08:21:26 AM

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Mike_Sims

Alright, I'm well aware of grounding/polarity/etc. when it comes to getting/preventing electrical shock. Our vocalist MIGHT be parting ways with the band due to personal issues, and I really don't want to find another vocalist, So I figured our bass player and I could give it a shot. Anyways, I've never sang + played guitar at the same time, the other night we had a show and the sound guy was checking our levels, I went to test the mic for our vocalist, while I had one hand on the plugged in guitar strings and touched my other hand to the mic I got shocked. My amps are both grounded, and I'm assuming (or at least I would hope) the venue is grounded as well... Had I been doing vocals as well, would it have been blister lips?

Hemisaurus

Why would you assume the venue was grounded? In my experience venues have some of the worst power around.

Also unless there is a common ground, which is rare outside recording studios, differences can exist in the ground levels between different phases of the circuit, ie. the PA isn't plugged into the same circuit (breaker) as your amps, so even though both are grounded there exists a voltage difference between them.

It's probably just crappy wiring though, expect to have this happen to you frequently :-X

LogicalFrank

Yeah, it's a bitch. Old venues (and old houses, rehearsal spots, &c.) can have some pretty funny wiring in there, esp. if it wasn't originally a venue like a lot of bars. Some dude throws in an outlet on the same circuit as the bathroom lights and the next thing you know it's running a PA and three enormous tube amps. I try to plug everything into the same power strip if I can to avoid polarity issues (well, now I have a cheap power conditioner which is basically a power strip in a rack) but there's not much you can do if the outlet isn't grounded.
"I have today made a discovery which will ensure the supremacy of German music for the next hundred years."

VOLVO)))

Polarity switch. Reverses the phase of your amps so you don't become the ground.
"I like a dolphin who gets down on a first date."  - Don G


CHUB CUB 4 LYFE.

Hemisaurus

#4
Plugging everything into the same outlet strip does actually make things better, because whether the outlets are grounded or not, they will have a common ground through the strip. Of course this only works if everything you own can run from the capacity of one strip. So that would mean your amps AND the PA.

Polarity reversal can be an issue, if either your equipment or the PA is wired oppositely, or if the outlets are wired backwards (lots of people don't know there is a right way and a wrong way to wire an outlet) but in some venues you may have multiple phases being used, so polarity reversal would only get you so far.

You can carry one of those little yellow test plugs around, I do, never have used it, don't know if I'd refuse to play a gig if the power was bad or not. I always worry about the gas mask going live and frying me, so I ungrounded my bass bridge, I have plastic pickup covers and it doesn't buzz, so I'm OK.

There are mod's out there on how to reground your guitar bridge, so that you won't get a shock, maybe just a tickle, I'm trying to remember is like a 1M or a 10M resistor and a bleeder cap I'll try and find where I got that. OK this chaps says 220K and a cap, adjust to suit, but obviously don't drop the resistance too low or it won't have any function.

http://www.singlecoil.com/docs/shock.pdf

hayseed

Getting the shock to the hand isn't so bad, its accidentally touching the mic with your lips that REALLY fuckin' hurts! I did that in my first band (almost 20yrs ago!) and it actually left a mark on my upper lip that lasted about a week or so. Its happened a few times since but i have learned not to eat mics since then and for that reason...as well a sanitary  issues at live events(good way to get herpes).s

Polarity switches are a god send! I was always told to unplug my amp and switch it to the lower or higher plug(depending where it plugged into) if i was getting juiced...that is obviously not going to work everytime.
"We just want to make the walls cave in and the ceiling collapse. Music is meant to be played as loudly as possible, really raw and punchy, and I'll punch out anyone who doesn't like it the way I do." - BON SCOTT, AC/DC

Hemisaurus

There's always mic protection, works good as long as you don't get it wet and spitty.


hayseed

Those are left over Muppet parts...by the looks of it they may have belonged to Bert & Ernie!
"We just want to make the walls cave in and the ceiling collapse. Music is meant to be played as loudly as possible, really raw and punchy, and I'll punch out anyone who doesn't like it the way I do." - BON SCOTT, AC/DC

Hemisaurus

#8
Anyone whose done some underwater recordings knows how to roll a condom onto an SM-58 :-X


Mike_Sims

That's funny... I was thinking about the mic cover idea... and sadly, the condom idea haha. Hmmm someone told me before if the amps are grounded or have the 3 prong plug that the polarity switch on the amp (sunn model T) doesn't make a difference? I kinda took that with a grain of salt though, being that I don't think they'd be on there for no reason.

I did notice Dixie Dave had a sock (?) wrapped all over his mic, haha.. Then again, Will from Zoroaster wasn't using any "shielding". Maybe that epic beard deflects energy

eyeprod

#10
When using my old gibson amp (two prong cord) with any other piece of equipment that has a 3 prong cord, I get shocked if I'm touching metal and then touch another metal object. It happened recently when I was using the amp for vocals. I was holding the mic that was going into the amp, then went to turn my guitar amp to standby. It's just more than enough to make you jump back. I want to get that old amp converted to a grounded plug. I've read that that's a problem when using old, ungrounded electronics in conjunction with grounded stuff. It's fine if you use it by itself, but add grounded gear to the mix and it causes problems.

Not sure if that might have anything to do with what happened to you. I figured I'd throw it out there.
CV - Slender Fungus

Hemisaurus

Yeah it's similar, that amp will be grounded in itself but whenever a true ground appears, like thru you, the microphone, and the PA to ground, it will take it, no matter how much it hurts you. That's actually the most dangerous path thru one arm across the heart to the other, that's the killer. :o


LogicalFrank

What you need to keep in mind w/ ungrounded amps is they are safe if they are a good design, in good working order and everything in the place is wired up correctly. If you use it places you're not sure on any of these, well, probably you should get a grounded chord installed.
"I have today made a discovery which will ensure the supremacy of German music for the next hundred years."

peyotepeddler

Quote from: Hemisaurus on March 14, 2011, 09:08:06 PM
Yeah it's similar, that amp will be grounded in itself but whenever a true ground appears, like thru you, the microphone, and the PA to ground, it will take it, no matter how much it hurts you. That's actually the most dangerous path thru one arm across the heart to the other, that's the killer. :o



well, if eyeprod disappears from the boards for to long we should send out a search and rescue, man down man down

Hemisaurus

Quote from: LogicalFrank on March 14, 2011, 09:30:07 PM
What you need to keep in mind w/ ungrounded amps is they are safe if they are a good design, in good working order and everything in the place is wired up correctly. If you use it places you're not sure on any of these, well, probably you should get a grounded chord installed.
Err, any amp is safe as long as it's a good design etc. etc. actually even the suicide amps are safe until...

It's when it goes wrong you have a problem, so get a grounded cord installed anyway ;)

VOLVO)))

FUCK GROUNDING, BE A CHAMP, ROCK IN WATER
"I like a dolphin who gets down on a first date."  - Don G


CHUB CUB 4 LYFE.

Hemisaurus

Quote from: SunnO))) on March 14, 2011, 11:49:31 PM
FUCK GROUNDING, BE A CHAMP, ROCK IN WATER
You americans are pussy with your 110V anyways, real men (and amps) use 240V ;D

VOLVO)))

YOU LIVE IN AMERICA, TOO, HEMI.
"I like a dolphin who gets down on a first date."  - Don G


CHUB CUB 4 LYFE.

Hemisaurus

Quote from: SunnO))) on March 14, 2011, 11:52:56 PM
YOU LIVE IN AMERICA, TOO, HEMI.
What makes you think that, eh ???

VOLVO)))

"I like a dolphin who gets down on a first date."  - Don G


CHUB CUB 4 LYFE.

Mike_Sims

LOL @ this whole thread now... My god damned amps are grounded!!! makes sense though, I get what you dudes are saying. Yeah I did actually have my pedals plugged into another power string other than the one my amps were plugged into. Oh well, fuck it, I'll rock in the water as Sunn O))) suggested. The odd thing is I've actually played guitar and *cough* tried *cough* to sing in my jam room at home (which is UN-grounded) and didn't get shocked at all... I guess completing the circuit through your hands is probably the easiest way to get zapped.

Hemisaurus

Like I said, the easiest things to do, are to unground your guitar (see earlier link to PDF) and to put a sock on the microphone.

These, while not an ideal solution, will save your ass (the ideal solution being that the nations venue owners get their electrical shit together, and people stop snipping ground pins of their gear).

inductorguitars

Before you play during sound check, touch yours strings to the mic, if it sparks it's unsafe.

db3jed

We were playing a joint one time that had the PA wired on a separate leg of the breaker box from the stage.
Our guitarist caught 220 VAC when he got on the mic during sound check (checked it with a volt meter).
I happened to be looking at him when it happened and saw the arc.
Wound up having to run dedicated extension cords out to front of house.

We played another place that had screwy voltage readings from every outlet on stage.
When we got into the area behind the stage we found every plug had been jumpered with barbed wire.
There's some crazy shit out there!

Yeah we've had to use socks before.
They're cooler looking than a wind screen too!
Never tried the condom thang though.

LogicalFrank

I am really just hoping hemi was serious that you could do that to record underwater...
"I have today made a discovery which will ensure the supremacy of German music for the next hundred years."