Page 1 of 5 1 2 3 ... LastLast
Results 1 to 10 of 47

Thread: Shocks to the lips from the mic

  1. #1
    Join Date
    Sep 2019
    Location
    Manchester England
    Posts
    6
    Thanks
    2
    Thanked 0 Times in 0 Posts
    Rep Power
    0

    Shocks to the lips from the mic

    Sign in to disable this ad
    Hi, I'm Boskins and I am a noob!

    I am setting up my first home studio and am getting mild electric shocks from my dynamic mic when I touch my guitar strings. The shocks are tingling like if you put a pp3 battery on your lips, not sharp shocks like static.

    I have checked, replaced, removed, re-ordered and reintroduced practically every part of the signal chain.

    With guitars attached to their amps and the mic attached alone to the mixer and speakers there is never a shock. Once I introduce a piece of equipment running on AC power to the mixer, the tingle returns. This happens when I attach a keyboard on AC or introduce an effects loop where the effects are running on AC.

    With the keyboard and the effects running on battery power there is no tingle so my assumption is that AC power is leaking through my signal chain

    I have checked the guitar amps, the mixer and the power strip are all correctly grounded, everything is running from the same strip and I have checked that my mains ring is correctly wired to ground. I have tried two separate mixers, switched out or updated many cables and tried introducing an external ground connection from the mixer and from the speaker casing.

    I haven't tried ground loop isolators yet but since these are designed to remove hum and I don't have any hum, I didn't want to buy more stuff I don't need. I realise that a foam shield on the mic could help but I don't want to just mask the problem. I want to get to the bottom of it.

    I am running out of things to try and would appreciate any suggestions as I am very keen to not electrocute my children or their friends.

    Many thanks, Boskins

  2. #2
    Join Date
    Apr 2005
    Location
    Lowell Street Studio, New England
    Posts
    12,175
    Thanks
    19
    Thanked 573 Times in 545 Posts
    Rep Power
    18632360
    No, some piece of your equipment is NOT grounded correctly. I would suspect the guitar amp as it happens no matter what other AC-connected device you add to the system.. Is it a 3-prong plug on it? The ground and negative may be tied together. This is a dangerous set up and I would advise you to not keep 'experimenting'.

    What 'mixer' are you using (it sounds like it may not be powered, or is USB or battery powered?) What amps, please provide all models/names of all your gewar.
    Mike B My new album on CD Baby: Fact and Fiction
    My Bandcamp site: http://mikebirchmusic.bandcamp.com

  3. #3
    Join Date
    Aug 2017
    Location
    Texas USA
    Posts
    2,118
    Thanks
    184
    Thanked 396 Times in 360 Posts
    Rep Power
    2298480
    As @mjbphotos suggests, the amp would be the first thing to look at. If it's not got a 3-prong plug it should be converted, but it should also have a ground switch that can be toggled, so try that. I'd also try a different guitar, mic and cords for both just to chase the problem from the mic/guitar ends back to the next piece of gear. Switch in a different amp, etc.

    And, buy an inexpensive AC line tester tool that can confirm your outlets are wired properly. Don't mess around with this stuff. If you find something wrong, get an electrician.
    "... I know in the mornin' that it's gonna be good
    when I stick out my elbows and they don't bump wood." - Bill Kirchen

  4. #4
    Join Date
    Sep 2019
    Location
    Manchester England
    Posts
    6
    Thanks
    2
    Thanked 0 Times in 0 Posts
    Rep Power
    0
    Thanks MJB and thanks for the safety warning. The two guitar amps have three pronged plugs, we call these kettle leads in the UK. They are a Fender Mustang 2 and an Orange crush 35b. The speakers attached to the mixer are powered nearfield studio monitors Roland MA15 which has a three pronged plug from the power outlet and a two terminal polarised power cord at the powered speaker end. The mixer is a behringer 1202FX which is powered through a type G three pin plug, the mic is a behringer MX8500, the keyboard is a Casio CTX700 and the external effects unit is a Boss RV6 reverb pedal.

    When you say the ground and the negative may be tied together, do you mean the power cord or inside the amp? The shocks persist whether I use both amps, one of them or the other so I thought it unlikely (although not impossible) that they were at fault.

  5. #5
    Join Date
    Aug 2005
    Location
    U.K.
    Age
    34
    Posts
    19,458
    Thanks
    1,205
    Thanked 1,026 Times in 906 Posts
    Rep Power
    1000000
    Quote Originally Posted by Boskins View Post
    Thanks MJB and thanks for the safety warning. The two guitar amps have three pronged plugs, we call these kettle leads in the UK. They are a Fender Mustang 2 and an Orange crush 35b. The speakers attached to the mixer are powered nearfield studio monitors Roland MA15 which has a three pronged plug from the power outlet and a two terminal polarised power cord at the powered speaker end. The mixer is a behringer 1202FX which is powered through a type G three pin plug, the mic is a behringer MX8500, the keyboard is a Casio CTX700 and the external effects unit is a Boss RV6 reverb pedal.

    When you say the ground and the negative may be tied together, do you mean the power cord or inside the amp? The shocks persist whether I use both amps, one of them or the other so I thought it unlikely (although not impossible) that they were at fault.
    Hi Boskins.
    Do you own a multimeter?
    If you do, with all equipment safely unplugged, I'd ensure continuity between the mains earth pin at the plug, and the chassis of the amp, of your guitar amplifiers.
    Any exposed nut/bolt/metal on the amp faceplate should be fine as a test point.

    It's reasonably common for 'smart' people to disconnect the mains pin, often just cutting the wire inside the plug, and it's not a good idea.

    It might not be the solution to your problem, but it's something I always check after seeing a few horror-story amps.
    ---------- Steenaudio Website ----------

  6. #6
    Join Date
    Sep 2019
    Location
    Manchester England
    Posts
    6
    Thanks
    2
    Thanked 0 Times in 0 Posts
    Rep Power
    0
    Thanks Steenamaroo. I will borrow a multimeter and check the continuity

  7. #7
    Join Date
    Sep 2019
    Location
    Manchester England
    Posts
    6
    Thanks
    2
    Thanked 0 Times in 0 Posts
    Rep Power
    0
    Quote Originally Posted by Steenamaroo View Post
    Hi Boskins.
    Do you own a multimeter?
    If you do, with all equipment safely unplugged, I'd ensure continuity between the mains earth pin at the plug, and the chassis of the amp, of your guitar amplifiers.
    Any exposed nut/bolt/metal on the amp faceplate should be fine as a test point.
    Hi Steenamaroo, I have now tested between the mains earth pin and the chassis' of the two guitar amps and both are showing continuity. I have also discounted the powered nearfield monitors attached to the mixer by replacing them with headphones and the issue is still there.

  8. #8
    Join Date
    Aug 2005
    Location
    U.K.
    Age
    34
    Posts
    19,458
    Thanks
    1,205
    Thanked 1,026 Times in 906 Posts
    Rep Power
    1000000
    Well, that's something. Safety first.
    I'm not an electrician or trained in the field, just to be clear,
    but I'm thinking maybe the Behringer power supply isolates from mains earth so its chassis is floating?
    It's nothing more than a guess but I've seen a lot of laptop power supplies do this, and your mic (and grill) would be getting their path to ground via the mixer.

    If I'm right I'm not sure what the proper, safe, remedy is. Thinking out loud more than anything.
    ---------- Steenaudio Website ----------

  9. The Following User Says Thank You to Steenamaroo For This Useful Post:


  10. #9
    Join Date
    Jan 2006
    Location
    Fremantle, Australia
    Age
    62
    Posts
    5,930
    Thanks
    0
    Thanked 220 Times in 202 Posts
    Rep Power
    11804435
    Try this as an earth check.

    If you have a guitar lead handy with a jack one end and bare wires on the other plug the jack into any unused socket on the mixer. Connect the shield end of the bare cable to any chassis screw on the guitar amp. Do you still get a shock?

    Alan.

  11. The Following User Says Thank You to witzendoz For This Useful Post:


  12. #10
    Join Date
    Dec 2013
    Location
    essex
    Posts
    2,866
    Thanks
    13
    Thanked 413 Times in 378 Posts
    Rep Power
    4008612
    These things can be a real devil to trace. Grounds /earths serve of course, two functions. The most important is to provide the absolute best path for a fault current to travel down when something goes wrong - the function that saves your life. The other function is the one the sound and music people like - it helps remove hum and noise. The real issue for the tingly shock syndrome is that earths/grounds are not all equal.

    I won't bore you with the electrical theory, but in most UK homes, the ground is derived locally, and the odd thing (for non-electrical bods) is that all that happens is that the neutral connection is physically joined to the earth in the place it comes into the building. By the time it gets to your studio space, or worse, your outside studio space, the Neutral and earth have drifted apart. In larger buildings - theatres and cinema type places, there can be a few volts difference between N and E. The upshot is this few volt difference can be where the hum gets into your sound system, or worse, where your guitar earth is not quite the same as the PA earth. Transformers in guitar amps can add to the problem, and in tube amps, the higher voltages can also leak. Amps (as in electrical Amps) kill. In fact, milliamps can kill, but you can feel very low levels of current on your lips, cheek, ears, back of your hand - places where skin is thin and nerves a plenty. Sometimes you can even generate sparks - tiny ones if you have a steady hand.

    I have a Strat that is very sensitive to me not touching the strings. When I take hands off, on one of my amps, it buzzes. My body mass is enough to sink the tiny current flowing.

    The snag of course is determining how much current actually flows through you, rather than down the earth cable. A normal meter cannot measure it - connecting it provides the path to get rid of it. If a normal meter does indicate current flow, I'd be very wary of touching the thing that is 'live'.

    A useful tip for tracking these things down is a short piece of cable with a couple of crocodile clips - you can dab it around your equipment touching cases to other cases, or guitars etc - and when the culprit is found you might hear or see a tiny spark. It's rare to find a spark that sustains, because that would be a serious fault worth a real electrician looking at for safety reasons - but if the tiny spark is a single one that doesn't come back for a second discharge after say a second - but does after a minute, the clue is there - Capacitors. Somewhere, and often again in the guitar amp are some capacitors that are charging from tiny current from the electronics - maybe leakage from a transformer, or other daft sources - even iffy phantom power supplies. touching your lips gives a good path to escape - and the familiar tingle.

    Do NOT expect a typical electrician to be able to find any of this stuff - not remotely what they trained to do. Electronics folk are the ones to find it, if you can't.

    I kept getting a shock on stage - I was too close to an FX light being used to project ripples onto a background and every time my right bare forearm touched it, it made me jump. A shock - a sharp tingle. It had a transformer and there was capacitor to ground - quite common in switch mode power supplies - often called a Y capacitor. Intended to reduce RF interference. just a rubbish design, not a real fault. swapping to a different power supply cured it.

    Proper systematic swapping and the little bit of cable with croc clips can point to the dodgy device - but if you're not completely happy with how this works, common sense says don't do it. Hum problems and shock problems are often similar ends of a different issue.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Digital interference/whine when mixer is connected to PC - also shocks
    By Robby Suavé in forum Digital Recording & Computers
    Replies: 6
    Last Post: 08-25-2016, 15:31
  2. Extreme Metal = Electro-Shocks
    By CarcPazu in forum MP3 Mixing Clinic
    Replies: 10
    Last Post: 04-11-2006, 15:12
  3. Studio Projects C4 pair w/shocks and box, $305 shipped
    By tubedude in forum Free Ads for Music/Recording Equipment
    Replies: 5
    Last Post: 03-23-2004, 03:28

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •