Members arcadesonfire Posted February 27, 2011 Members Share Posted February 27, 2011 I'm wondering if my band should get a power conditioner for our rehearsal space. We pay a monthly fee and share a room in a many-studio rehearsal building in Brooklyn. Our keyboardist is now play bass guitar on half our songs, and he sings lead. Since he started playing bass, we've been running the bass through a PA, but he got an amp this week. But when we had it plugged in and he had his hands on the bass strings and tried to sing, he got terrible shocks from the mic. When we held the bass strings up to the mic, we could see blue sparks (even when we turned the bass amp off!). Not only that, but there's a lot of hum/noise from both the bass and in my guitar amps. (i reduced a lot of noise when i got the voodoo lab power supply for my pedals, but still, there's some extraneous noise from my amps.) So i'm assuming that there's some faulty grounding in this room. I haven't even found the main outlets. We just use the power strips that are out in the middle of the floor. If we got a power conditioner and then plugged all the power strips into that one source, would this problem be solved? Link to comment Share on other sites More sharing options...
Members Redbassman86 Posted February 27, 2011 Members Share Posted February 27, 2011 A power conditioner will not help this shocking issue. Since the building is rented, I suggest you contact your landlord about having a Licensed Electrician inspect the wiring in your building. It could be the equipment (say a non-polarized two prong plug on the amplifier), but I'm willing to bet unsafe wiring. DO NOT use one of those three prong to two prong power plug adapters, in fact if you own one, throw it in the trash. This is NOT generally a problem solved by easy methods, and is most likely a lack of grounding wire connection somewhere in the current path, which is better left to the professionals. Sorry for being so passionate, but I happen to be an Electrical Contractor, as well as a Pro Sound Contractor, and I have seen every possible unsafe work-around to this problem by amateurs who say "oh no, this is ok". I have also been railed pretty hard off of a microphone at a club because the house engineer thought it was "ok" to fix the outlet himself. The Neutral and the Ground are NOT the same thing, and it is NOT ok to tie them together anywhere but in a Main Panel, and NO ONE UNQUALIFIED should be in there. Have it checked by a pro, it could save your life RANT OVER Link to comment Share on other sites More sharing options...
Members jeff grocki Posted February 27, 2011 Members Share Posted February 27, 2011 Agree with RedBass shocks are in no way good!!! Don't fool with it. Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 27, 2011 Members Share Posted February 27, 2011 conditioner will not solve your problem. Link to comment Share on other sites More sharing options...
Members TimmyP Posted February 27, 2011 Members Share Posted February 27, 2011 Plug the bass rig into the same outlet that's powering the mixer. Link to comment Share on other sites More sharing options...
Members W. M. Hellinger Posted February 27, 2011 Members Share Posted February 27, 2011 Plug the bass rig into the same outlet that's powering the mixer. of-course: after checking that outlet... assuming of-course the outlet checks out Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 27, 2011 Members Share Posted February 27, 2011 Plug the bass rig into the same outlet that's powering the mixer. That won't fix a shocking problem. This is due to something in the signal chain leaking voltage to what should be at ground potential but is not. Electrician needs to verify proper grounding, and then the offending piece of equipment needs to be identified and repaired. Link to comment Share on other sites More sharing options...
Members arcadesonfire Posted February 28, 2011 Author Members Share Posted February 28, 2011 Thanks everybody, and big thanks to Redbass. The PA is not top-quality. They're running a mixer into two old peavey mixer/poweramps. I tried finding the outlet they're plugged into tonight, but there's so much {censored} in that corner of the room, the power cables were running under piles of stuff and i couldn't even find the source. I'm thinking it's very likely those PAs aren't properly grounded (that someone may have removed a ground prong for convenience sake years ago). We told the guy we sublet the room from, and he told us to write out our complaint and he'd take it to the building owners, so we ought to get this taken care of. In the meantime, we won't use microphones. Thanks again. Link to comment Share on other sites More sharing options...
Members The Chinese Posted February 28, 2011 Members Share Posted February 28, 2011 There's a really good chance that it has nothign to do with the building power, but rather a faulty piece of gear...Is the bass amp a tube amp by chance? does anyone else get shocked with their amps/mic (especially you?)? If all that's changed is that a Bass amp has been added, then there's a likely culprit. Note that I am NOT saying that it isn't a room issue; we don't know. But it stinks like a bad piece of gear rather than a building issue. Fairly easy to test with a simple Test Plug- these will tell you if you have a reversed Hot & Neutral, Reversed Ground & Hot etc et al. They cost about $10, and take no experience to use & are completely safe. I would get one and always have it with you, and always test any outlet you are plugging into. Todd A. Link to comment Share on other sites More sharing options...
Members Redbassman86 Posted February 28, 2011 Members Share Posted February 28, 2011 There's a really good chance that it has nothign to do with the building power, but rather a faulty piece of gear...Is the bass amp a tube amp by chance? does anyone else get shocked with their amps/mic (especially you?)? If all that's changed is that a Bass amp has been added, then there's a likely culprit. Note that I am NOT saying that it isn't a room issue; we don't know. But it stinks like a bad piece of gear rather than a building issue. Fairly easy to test with a simple Test Plug- these will tell you if you have a reversed Hot & Neutral, Reversed Ground & Hot etc et al. They cost about $10, and take no experience to use & are completely safe. I would get one and always have it with you, and always test any outlet you are plugging into. Todd A. Also good advice. Plenty of things go wrong with instrument amps that cause this problem, #1 in my book being the older unpolarized plugs being inserted backwards causing the chassis to be lit with 120v. +1 on the outlet tester. Todd, based on the description of the problems he listed, I'm thinking of a few things that might be wrong, and if he were the homeowner, I would suggest a few things for him to check out. Since he is a renter, it shouldn't cost him a thing to have the building owner confirm that the grounding in his building is safe, and people shouldn't screw around with things on rental property, it causes people like me to make a living A lot to be said for piece of mind. Link to comment Share on other sites More sharing options...
Members The Chinese Posted February 28, 2011 Members Share Posted February 28, 2011 Yup. truth there. Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 28, 2011 Members Share Posted February 28, 2011 Back many years ago, when many power systems were ungrounded, the only way to reference a chassis to anything resembling a ground or at least a low impedance to the power supply was to connect the chassis to one side or the other of the power system through a small high voltage capacitor which provided "isolation" at low frequencies but looked like a direct connection at high frequencies (like RF). This provided better noise performance but the leakage current to the chassis was on the order of a mA or so and under the right conditions like the plug reversed or the ground tie switch set to the wrong position caused either more hum or a slight shock. Probably not dangerous BUT, over time these caps degrade and the leakage current can get very high which is where the big shock comes from. Today, nearly all power systems are grounded, and anything ungrounded is generally polarized (notice that one blade is wider then the other) so the problem is nowhere near as common. Link to comment Share on other sites More sharing options...
Members Redbassman86 Posted February 28, 2011 Members Share Posted February 28, 2011 Now that I didn't know. Pretty damn interesting Link to comment Share on other sites More sharing options...
Members Hegmatronicon Posted March 1, 2011 Members Share Posted March 1, 2011 We had the same issue recently in our space. Turned out to be an extension cable we were using causing the issue. As soon as our singer/guitarist changed the cable (it was running his tube amp) the problem was solved. Link to comment Share on other sites More sharing options...
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