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Need help - getting small shocks from my mic

#23
As an aside:
I had a hot rodded Fender guitar amp once that was tweaked by a local tube amp guru
Sounded great until I walked onto bare concrete from carpet while barefooted
Measure over 400 Volts DC from the strings to the concrete floor; we had a chat after that incident
 
#27
guylewis said:
Does the PA mixer have a facility to supply Phantom Power for powered mics? If it does . . . switch it off!

If its not that; get it checked out by an electrician pronto.
Click to expand...

Phantom power isn't the problem. All that does is raise the twin cores of the mic cable to around 48V. it never reaches the shell of the mic and if it did it would probably burn the mic element out. I've used condenser mics exclusively since the seventies.

The problem IS bad grounding somewhere. The OP should get all the equipment checked.

Paul
 
#29
Quick electrical lesson.

Today we have 3 wires. Hot, Neutral, Ground.
Hot should be the smaller of the two flat blades, Neutral should be the wider, and ground the round or 'U' shaped one.

If you measure between hot and neutral or hot and ground, you should get 120v. If you measure between neutral and ground, you should get 0 volts.

If you have two power amps and one has the neutral and ground switched you CAN get voltage [that should be] going back out the neutral flowing to ground. i.e. your mic or your strings. will feel like a 9 volt on your tongue or a hum.

If you have a power amp with hot and neutral switched, you may get some voltage to ground. But, usually just a hum.

Now, if you have two power amps with a hot and ground switched, you WILL get 120volts flowing through you to ground. Mic to strings or vis-versa.

Now to scare you.... If you have two power amps with the hot on the ground and they are plugged into two differently phased circuits. YOUR DEAD! 240 volts with probably 40 amps.

You just took two hot wires = 240+ volts and stuck them on your body.

ASK ME HOW I KNOW..... I got lucky.

Get a tester, and check all the plugs that the band may be using. If you find one out of sync with the others, don't use it.

You've not doubt seen musicians walk up to the mic and tap (open palm) on the mic while holding their strings?

That's why.
 
#30
Oh, yes you can have something messed up on the DC voltage side of the transformer too. If you take a volt/ohm meter and measure the metal case of your amp or sleeve (outside part) on your cord to ground (literally to the ground on the 120v AC power supply), and you find voltage... You probably have a internal circuit board problem. This is best checked out by an amp repair shop.

Paul
 
#32
Heres how I have solved this problem. Works every time. PLUG EVERYTHING INTO THE SAME WALL PLUG. Grounds, hots, neutrals are now all the same in every amp.

Better yet do what Rick said: Get a outlet tester (6 to 8 bucks at Home Depot) and test every outlet before set up. Use only outlets that are wired right. Tell or show the manager why you will not use the other outlets.
 
#34
bassandbeyond said:
A quick, cheap solution for these situations is to use a non-conductive windscreen on your mic....always practice safe singing! ;)

But the REAL solution is to get all your gear fixed and properly grounded.
Click to expand...

Getting stung on the lips hurts like heck. A foam windscreen can help tremendously, but as noted, use this only as a temporary workaround... it's best to solve the grounding problem.
 
#35
James Judson said:
Heres how I have solved this problem. Works every time. PLUG EVERYTHING INTO THE SAME WALL PLUG. Grounds, hots, neutrals are now all the same in every amp.

Better yet do what Rick said: Get a outlet tester (6 to 8 bucks at Home Depot) and test every outlet before set up. Use only outlets that are wired right. Tell or show the manager why you will not use the other outlets.
Click to expand...

These are good things to do, don't get me wrong, but they won't help if an amp has a hot chassis.
 
#38
Rick Auricchio said:
True, but you're just as dead with 120v as with 240v.
Click to expand...

Yea, I know... It just takes a little longer.

It's always been a standing rule when checking higher voltage things, to use a clip for ground and only probe with one hand inside/around the power. (Hard sometimes if your probing for burned out components).

This way it greatly reduces the chance of passing volt/amps through your chest. If you get electrocuted from say elbow to fingers, it's one thing but, to make a circuit with your heart in the middle is another.
 
#39
shocks are great arguments in favor of wirelesses. and active bass preamps, since they don't need a ground wired to the strings. but i'm not big on them. i like wirelesses a lot better.
 
#40
This is great info guys - I am pretty sure the problem lies within the PA or my amp. I will get them looked at. Could it possibly be just the power lead itself and not within the amp (it's a typical what I would call a kettle cord!). I have some spares. Or even the 4x10 cab that I use? Up until the last few gigs I have used a 1x15 but just decided lately to use the 4x10 that hasn't been used for about 8 months. Other than that I will take the amp to a repairer to check out.
 

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