Microphone shocking

[Marvin]

Our singer is saying that she's getting an electrical sensation when holding the microphone. 

 

Someone suggested that the phantom power might be on on the mixer. However,  I can't remember seeing the phantom power light on on the mixer and the guitarist said he checked it was off.

 

The sensation is all the time. She's tried a different mic, changed the cable,  stood a a rubber floor mat, not stood on the mat. Still the same.

 

The phantom power seemed the obvious culprit but apparently not (unless there's a fault in the desk).

 

Any ideas?

 

Ta.

 

Edited Friday at 18:10 by Marvin

[Chienmortbb]

This is odd. There is no reason that the singer should get a shock from a mic unless there is a fault on the mixer and that would be unusual. You need to measure the voltage between the mic grille and earth. It should be very small, millivolts ideally.  

[Bill Fitzmaurice]

This was common in the days before 3 wire mains cables were used, which insure that all devices are properly grounded. But it usually presented a problem only if one was holding a guitar and touching the mic. Just holding a mic should never present a problem. Even if the mic body is receiving current she would have to be a path to ground to feel anything. Have you had someone else hold the mic to see if they feel it? 

[Stub Mandrel]

I've had this a couple of times.

 

Not mains shock, but a lip tingle - being moist and crammed with receptor cells the lips are very sensitive to static and fairly low potentials.

 

These days a cause can be double-insulated gear 'floating' above ground, one cause can be both ends of a signal chain with a ground lift perhaps made worse by leakage across ans SMPSU.

 

Double insulated chargers can do this.

 

So perhaps start by checking the mic's ground is continuous with earth.

[Newfoundfreedom]

Get a wireless mic adapter. Solved the problem for me. No chance of current running through cables to the mic.

We have a 2 wire negative earth system here in Bulgaria and I wouldn't trust putting my body parts anywhere near it. Fully wireless for the bass and mic. 

[JapanAxe]

9 hours ago, Stub Mandrel said:

I've had this a couple of times.

 

Not mains shock, but a lip tingle - being moist and crammed with receptor cells the lips are very sensitive to static and fairly low potentials.

 

These days a cause can be double-insulated gear 'floating' above ground, one cause can be both ends of a signal chain with a ground lift perhaps made worse by leakage across ans SMPSU.

 

Double insulated chargers can do this.

 

So perhaps start by checking the mic's ground is continuous with earth.

This.

 

I’ve measured (and felt!) 70-80V between the output of a 9V switched mode wall wart and ground. Earthing the connected device made the problem go away.

[Marvin]

On 22/08/2025 at 20:12, Bill Fitzmaurice said:

This was common in the days before 3 wire mains cables were used, which insure that all devices are properly grounded. But it usually presented a problem only if one was holding a guitar and touching the mic. Just holding a mic should never present a problem. Even if the mic body is receiving current she would have to be a path to ground to feel anything. Have you had someone else hold the mic to see if they feel it? 

 

No, we haven't tried someone else holding the mic.  It'll be the next step, as the desk is new, the mic is new as was the cable at the last practice.