Well, yeah, again, electric shocks from mics !!

[Mike Stranks]

Whoa!

Isn't Social Media fun... sometimes?

When I looked back at the start of the thread, I saw three names (at least) from days gone by, whose opinions I valued...

They're not around any more... that's all... no criticism, moaning, soul-searching, 'Is something wrong here that's made them do that?' on my part... just a bit of reflective nostalgia...

... and relax...

[bedazzled_k]

Hi

So, I've looked through this thread but I'm still not sure what's causing my situation. I'm getting small shocks when my lips touch the mic (I'm a guitar player). This is happening at home but I can test it at the rehearsal space we use next week.

I've got a Labgear socket tester and all of the sockets I'm using are showing as 'CORRECT'.

My setup is as follows:

Schmidt Array pedalboard with TRS patchpanel.
Microphone into TRS socket on patch panel into Boss VE-500. Outputs into patch panel. Output #1 to Gear4Music WPM-200 radio transmitter.
I'm also using the patch panel for guitar in, and guitar out to amp.
The effects (including VE-500) are powered with a Voodoo Lab Pedal Power3 and Pedal Power X 8.
I'm also using a GigRig G3 and its Generator power supply.
The Schmidt Array pedalboard has IEC sockets and the PP3 and Generator are using these. The two power cables are going into an extension lead which is also used by the Gear4Music radio transmitter PSU.

I'm getting the shocks with both an AC-30 and Fender Twin Reverb; both of these amps were recently serviced as well. These are not using the same extension lead as the pedalboard/mic transmitter but are in the same room.

If I use my Audio Technica System-10 wireless guitar rig then I don't get any shocks.

Any thoughts as to what may be causing this issue? As I said, they're not big shocks but I'd obviously rather not have any!

Thanks,

Kevin

[Hugh Robjohns]

I'd lay money on the boss ve500 not being grounded.

[bedazzled_k]

I'd lay money on the boss ve500 not being grounded.

Thanks Rob. It's powered with 9V DC from the Pedal Power 3. Is there a way of ensuring it's grounded?

[Hugh Robjohns]

Yeah... ground it!

Find something that's already grounded, like a guitar amp, and link a wire from there to the mic cable screen.

Just to test the hypothesis, you could ask a friend to hold the plug tip of a guitar lead against the metal barrel of your guitar lead at the patch bay, with the other end touching the metal barrel of the mic lead at the patch bay. That will ground the mic to the guitar amp and will hopefully cure the problem.

As a general rule, 'small shocks' are caused by one of two possibilities.

1. Static from your clothes discharging to a grounded mic

2. Metal parts of ungrounded equipment floating up to half mains voltage and discharging through a grounded person.

The first will happen once and then not on repeated contacts (unless you charge yourself up again by moving s lot or shuffling on the carpet). The second tends to happen on every contact.

[bedazzled_k]

Thanks, that makes sense! I’m not with my gear at the moment but presumably a wire attached to the metal chassis of the Boss and the guitar amp will suffice?

[ef37a]

I suspect the shocks are 'tingles' from unearthed equipment as well.

One solution is a foam gag on the mic but you must, must, MUST get the actual safety of all the kit checked out first before such palliative step.

You will also need to keep the gag dry.

Dave.

[pk.roberts]

The Labgear socket testers are a very simple devices and will NOT necessarily indicate the presence of a good earth connection. To do that you need something like the Martindale EZ165 or a Socket & See SOK34.
In the dim and distant past, I witnessed someone getting a full-on mains shock from a 'live mic' and it's not a sight I'll ever forget, so please get your gear checked by a competent person as soon as possible.
I'm sure that Dave wasn't suggesting that you use a foam pop shield on the mic as some kind of stop-gap, temporary solution.

[ef37a]

The Labgear socket testers are a very simple devices and will NOT necessarily indicate the presence of a good earth connection. To do that you need something like the Martindale EZ165 or a Socket & See SOK34.
In the dim and distant past, I witnessed someone getting a full-on mains shock from a 'live mic' and it's not a sight I'll ever forget, so please get your gear checked by a competent person as soon as possible.
I'm sure that Dave wasn't suggesting that you use a foam pop shield on the mic as some kind of stop-gap, temporary solution.

No indeed and I don't know how much more strongly I could have worded my reply to say get the gear checked professionally?

A spit gag is a good idea anyway.

Dave.

[bedazzled_k]

Thanks for everyone's thoughts and advice; I will look at getting a better tester for starters.

If the issue is indeed the Boss VE-500 (I haven't had chance to test Hugh's suggestion yet) then would it be rectified by using a separate PSU, rather than the one I'm also using for my guitar effects? I note that the Boss PSU is ungrounded.

Thanks

Kevin

[Philbo King]

I had a similar problem at an outdoors venue where the PA console was around 200 feet from the stage and operating off a different circuit (likely with a faulty ground somewhere). I left the high E string 6" long at the headstock, and when it brushed across the mic it threw sparks.

My somewhat unsafe, but usable, solution was to put a thick dry cotton stocking (a sock) over the mic to insulate it from my lips. And tell the mix engineer to boost my vocal treble to compensate for the loss of highs due to the sock. Ever since that day I always keep a pair of those socks in my guitar case.

*Use this at your own risk! There are fault scenarios where this could cause fatal shock*

[Lostgallifreyan]

Thanks for everyone's thoughts and advice; I will look at getting a better tester for starters.

Sometimes a cheap digital DMM, the kind that can be had for as little as £2.50, can be useful. The continuity tester is useful to test grounds because if there is anything other than a clean strong connection, especially one with any erratic voltage across it, the meter's sounder will make a crude sound instead of a steady pitch, and the reading will likely get crazy and not diagnostically useful.

Because these cheap meters get weirded out so easily in continuity testing, they won't reliably tell you what is wrong, but they will tell you that is IS wrong. If they read clean and low resistance, and beep with steady pitch, the continuity is likely to be very good. Try waggling connectors while doing this, it's a great way to find loose ones.

Even a rotten tool can be useful if the results are consistent, and if it speaks true when conditions are good. Just got to be careful how to interpret it sometimes... In emergencies, it might keep you alive, and let the show go on.

-----

When approaching unknown metalwork in some mains-powered rig, I usually make the first touch gently with the backs of my fingers. If there's a strong AC charge you'll feel it, and even if it's DC your fingers will involuntarily curl inwards, away from the point of contact. If that is safe, then a very gentle rub with the backs of the same fingers can tell you if ungrounded mains equipment is 'floating' and putting some AC voltage on the ground line. Current is probably low if the touch test gets this far, but it could still cause unrest if touched by damp skin. Even 12V can be truly dangerous to an open wound. It can drive a lethal current, hence the advice on order of connecting jump leads in cars because the scale of the situation can result in 12V being driven through the heart when people handle uninsulated crocodile clips while leaning against the metalwork..

Gentle touch testing with the back of a finger can save your life (as compared to trusting and grabbing), and electricians sometimes keep one hand in a pocket if they don't need it when they can't isolate the equipment.

[ajay_m]

Double insulated PSUs vary widely in the amount of leakage current they permit via capacitive coupling via transformer windings. It is not uncommon to feel a vibrating sensation when touching ungrounded metalwork in that scenario though the actual current is pretty small. I should think that particularly sensitive body parts like lips would obviously detect this more as well.

[ef37a]

Double insulated PSUs vary widely in the amount of leakage current they permit via capacitive coupling via transformer windings. It is not uncommon to feel a vibrating sensation when touching ungrounded metalwork in that scenario though the actual current is pretty small. I should think that particularly sensitive body parts like lips would obviously detect this more as well.

Agreed, the problem can be avoided by using a 3 core mains connection and earthing the (negative?) DC output via a IM resistor but of course that cost more than a 'fig 8' bi pin socket and a 2 core cable.

Dave.