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Gear / Technical Help => Microphones & Setup => Topic started by: stlawrence on May 21, 2007, 01:52:44 PM
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This is really a performance question, but hoping some TS gurus can help me out. I run a Shure 58 and a Shure Beta 58 for solo gigs, and am getting a low buzz out of them through the PA. It goes away when I touch the microphone, assumedly because I'm grounding the circuit. It's enough electricity that I get shocked when my lips touch the mic. Also, it happens regardless of whether Phantom Power is on on the mixer. Any ideas on how to ground that to eliminate the buzz?
Thanks in advance
Stratton
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you don't need phantom power for those mics first. If you are getting shocked you need to look at the power supply for the PA. Is this your PA you are bringing with you or does it belong to the club. does this happen in all clubs or just one.
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It's my PA, a mackie dfx-6. I am plugging it into an extension cord directly from the wall, and have not noticed the problem at home, just at the bar, which is the one other place I regularly play. Maybe a surge protector would fix it? Any suggestions?
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do you get shocked all the time, or just when you are holding your electric guitar?
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do you get shocked all the time, or just when you are holding your electric guitar?
That was my next question. are the guitar amp and the board plugged into the same outlet?
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Obviously you are NOT grounding the PA/mic system. A surge protector does nothing for this.
Make sure you are plugging into a fully grounded 3-pin AC socket at the club, and your extension cords are all 3-wire with ground types. Sometimes a three pin wall socket is NOT properly wired to ground, so try a few others until the hum and shock value goes away.
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I play an acoustic with an active internal pickup that I plug directly into its own channel on the mixer. The "shock" isn't terrible, but annoying enough that it effects me when I'm singing and get zapped. When I was setting up on Friday, I had the problem before picking up the guitar
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Thanks guys. Sounds like its power supply. At the bar their outlets are two prong, so I have a little adaptor for my power strip. That must be it.
Interestingly though, my jam room also has two prongs, and I do the same thing without issue.
I'm going to get a long extension cord and just run around the wall to find a three prong at the bar.
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I work at a couple of bars that have questionable wiring. I cary a simple $10 polarity checker just for this purpose. If the outlet you are using is not grounded (there isn't much you can do to convince the bar to do anything about it) use one of those 3 prong to 2 prong plug adapters BUT YOU HAVE TO USE IT RIGHT! unscrew the screw that holds the cover on the outlet and atach the tab at the bottom of the adapter to it. This will add a ground to the building. no guarantee but it should help.
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Thanks guys. Sounds like its power supply. At the bar their outlets are two prong, so I have a little adaptor for my power strip. That must be it.
Interestingly though, my jam room also has two prongs, and I do the same thing without issue.
I'm going to get a long extension cord and just run around the wall to find a three prong at the bar.
or use the ground lift adapter correctly and tie the tab to the screw on the wall plate.
and tell the bar to get their electrical up to code.
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^^ great minds think alike... +T
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lol....within 7 seconds of each other. funny!
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I'm on it. Thanks again!
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Since you had everything working at home ON A CIRCUIT WITHOUT 3-wire socket, there is another possible cause for loss of ground that's potentially dangerous to be sometimes lethal if running high voltage tube type guitar amp ungrounded with other AC powered gear.
First thing is to assume you are always PLUGGING EVERYTHING INTO THE SAME POWER STRIP AS YOU SHOULD, and then connecting to a source of AC power sometimes using extension cords. While the advice given so far is appropriate, sometimes the loss of ground is BETWEEN one or more gear plugs grounds even though they are all using 3 wire plugs into the same power strip. This sometimes happens if the ground wire breaks inside the power plug going to something, or the power strip itself has gotten worn to maybe sometimes not be making a good connection to the ground pins of some plugs.
So you need to inspect all your equipment's power plugs and see if they are all making good ground connection with the equipment that's being powered, replacing the plug on the cord if showing broken or severely worn condition. Also look to see if it's time to replace your power strip you use on gigs to one that's well made and makes tight connections to the ground pins on power plugs.
If ALL YOUR GEAR your gear is well grounded to EACH OTHER, then you will NOT get a shock by touching a mic connected to an amp connected to the same power strip with any other grounded gear being powered by the same power strip.
However, while all the power-strip connected gear may be quite safe to handle (if all making good ground connections) without fear of shock, IF THE POWER STRIP IS NOT CONNECTED TO A 3 PIN GROUNDED SOURCE OF AC POWER, you may still get a dangerous shock if touching SOMETHING ELSE THAT'S ACTUALLY GROUNDED not associated with your own gear.
And that's why it's a hazard to work off 2 wire ungrounded AC with AC powered audio gear.
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Agree with all above advice - As a last resort - carry a windscreen with you - at least that way you can minimize the annoying shocks(you'll still have the noise)...handy - especially when you are not the soundperson... ;)
If all else fails, carry a 6ft copper spike with you...drive it into the ground, and run a wire back to your 3 wire adapter... >:D
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This is really a performance question, but hoping some TS gurus can help me out. I run a Shure 58 and a Shure Beta 58 for solo gigs, and am getting a low buzz out of them through the PA. It goes away when I touch the microphone, assumedly because I'm grounding the circuit. It's enough electricity that I get shocked when my lips touch the mic. Also, it happens regardless of whether Phantom Power is on on the mixer. Any ideas on how to ground that to eliminate the buzz?
Thanks in advance
Stratton
If your using a acoustic guitar with a DI I assume your mic and your guitar are both plugged into the same mixer?
If your guitar and mic are in the same mixer. Then it can be one of two things your mixer is not grounded.. You could have plunged your mixer in "backwards" into the wall outlet reversing the Neutral and Hot.. This means with respect to ground your mixer is now hot.. So if your sitting on a concrete floor with a bar stool... You are making the connection between the mixer and ground. The voltage from your mixer is "leaking" thru you.. To test this connect a volt meter between a ground source and your mixer you should see 0 volts if you dont then you can assume that the improper grounding of your mixer is to blame. As has been suggested here I would invest in a cheap outlet tester and Never EVER bypass ground on your gear If there is not an outlet with a ground you need to look until you find one. But I would recommend using a outlet tester to make sure its really grounded.
EDIT: Actually I misunderstood what RP was saying.. He was saying if you are going to use a ground lift adaptor please make sure that the ground tab is secured to the outlet screw. I say dont use an outlet where you have to use a ground cheater. The ground "cheater" The screw is not guaranteed on an outlet to be at ground potential and therefore is not recommended as a means of ground. Here in Canada they dont sell them anymore because people were using them and attaching them to the outlet faceplate screw and assuming it was grounded. They were still getting shocked in some cases because on old outlets there is no ground going to the outlet box therefor the screw is not grounded.
Here is what a basic outlet tester looks like.
http://www.globaltestsupply.com/test_equipment/AEMC_OT-1_Outlet_Tester_.cfm
I once worked with a band and the guitar player got electrocuted on stage.. When I was doing sound.. It was not a pretty sight, and it was because the house sound system's power was not wired correctly. From that day on I have always carried an outlet tester and before any band I work with plugs anything in all outlets get tested. This is $7.95 cents that can save your life.. The guitar player was ok he was resuscitated on the scene there was a doctor in the crowd and he was rushed to the hospital he suffers from memory loss and nerve damage to this day.
Chris
please go out to a hardware store and buy one of these things and always use it and never play with out a proper ground for your mixer its there for a reason.
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The ground "cheater" that was suggested by Rockpunk I would not recommend, Because if the outlet does not have a ground pin on it. the screw is not going to ground your gear since outlet boxes that do not contain a up to date Edison plug with the ground tab are generally not grounded. So relying on a ground cheater with a screw tab to the face plate is not a guarantee of grounding.
I wasn't advocating the use of a ground lift adapter....I was merely suggesting that if one is used, it needs to be used correctly.
I wouldn't even consider using an ungrounded outlet for my PA gear. I tie my power distro right to the breaker panel, bypassing the need to use the bar/club/venues outlets at all.
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The ground "cheater" that was suggested by Rockpunk I would not recommend, Because if the outlet does not have a ground pin on it. the screw is not going to ground your gear since outlet boxes that do not contain a up to date Edison plug with the ground tab are generally not grounded. So relying on a ground cheater with a screw tab to the face plate is not a guarantee of grounding.
I wasn't advocating the use of a ground lift adapter....I was merely suggesting that if one is used, it needs to be used correctly.
I wouldn't even consider using an ungrounded outlet for my PA gear. I tie my power distro right to the breaker panel, bypassing the need to use the bar/club/venues outlets at all.
Sorry for the misunderstanding.. :) I will edit my post.... I should have read it more clearly
Chris
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that was my point as well. IF you are using a ground lift PLEASE use it correctly!