Paul Supersonix Studios wrote:yeah well as hundreds of professional touring chart topping artists play there every year you would have thought that it would be properly earthed? maybe not,
The first rule of not dying is to not make assumptions like that. Faults happen. Things can change. When we rigged for some SOS seminars at the old Wembley Arena site, I found four faulty sockets in the same conference room -- a room that was used everyday by all and sundry. One socket had no earth, two were live-neutral reversed, and one just had no power. It happens! Often, the screws clamping the cables inside work lose or tarniosh and oxidise. Sometimes they weren't done up tight in the firtst place, and as the cable oxidises the connection goes high-resistance. That's all that's needed to make the safety earth next to useless! Sometimes someone else has had a major fault and the cable or the socket has been damaged but not reported to be fixed. Hence my advice to check them before using them.
the reason i said it wasn't the guitar amp was because i was getting shocks(and i play bass and sing) and so was our guitarist(who also sings) and its never happened before?
Were both your amps plugged into the same mains extension plug board by any chance? Or the same wall socket? If so, you've probably just identified where the missing earth was.
Clearly, there was a serious and potentially fatal fault somewhere. It could have been the earths protecting the sound desk, or it could have been the earths protecting the guitar and bass amps.
In my experience, shocks when touching a microphone are almost always because the mic body is properly earthed but the guitar amp's earth is disconnected, so that the 'earthed' metalwork on the amp (and guitar string earthing) floats up to half mains voltage (115V).
You won't feel that while playing as long as you don't touch anything else earthed, but the moment you do, you'll get the shock.
Now the missing earth might not be because the safety earths in the amps have been deliberately disconnected -- it could just as easily be because a mains cable or extension board has been damaged, or the wall socket could be faulty, as I've explaiend.
It's a less common scenario, but certainly still one worth investigating, that it could equally have been the other way around -- the guitar amps were properly earthed and it as the mixing console earth that was at fault. In that case, the mic's body would have floated to 115V, but you would have got the same tingle effect through the grounded strings.
Sadly, without all the same equipment set up in the same room in the same way, we'll only ever be guessing what the actual problem was. But it would be foolish to dismiss it and not check everything you can carefully.
As I said, the location of that discontinuous earth (or earths -- there could be more than one fault here) could be at any of a variety of places. The wall sockets, the extension cables, the mains plugs, the mains cables, the pluig-boards, or inside the equipment itself. The only way to be sure is to check every single mains cable you used, every extension cable, and every piece of equipment.
In fact, this really is something you should do regularly anyway. Cables get snagged and cut, or tripped over pulling the wires from the plugs, and screw connections inside plugs can work loose and wires corrode and oxidise.
If they all check out okay, then it was probably the mains sockets in the venue -- it really isn't that uncommon! Buy a tester, and make a point of using it next time. it only take a few seconds. Also, to be almost completely safe, make sure you run all your own equipment through an RCD, and persaude all the others in the band (and FOH) to use RCDs too.
Hugh
