Annoying Shocks, Ground Loops and Monitors..etc

Discussion in 'Monitoring' started by edaub1, Jan 23, 2015.

  1. edaub1

    edaub1 Active Member

    Jun 10, 2009
    Ok here we go.. I've had this issue for awhile now and I'm finally getting super annoyed with it.

    I have a desk with a built in rack. The only pieces I use are my Furman power conditioner, presonus fire studio project and an Alesis RA-150 Amplifier for my monitors. Almost anytime i want to plug in my headphones I have to touch the connector to something metal first (i can hear an audible shock) before i plug it in to the headphone jack of the Presonus. If I don't do this.. the Presonus will get a shock or something and the LED clip lights will all go off. I then have to turn off the unit and restart it.

    How can I avoid this. Is having a rug causing this?

    There is also a slight hum if i crank the gain knobs of the headphones or monitor output of the Presonus.

    Do I have a ground loop somewhere?
  2. Boswell

    Boswell Moderator Well-Known Member

    Apr 19, 2006
    Home Page:
    It's you that's getting charged up and not the equipment. My guess is that your chair seat cover is made of a material that when you rub over it wearing trousers, you generate a static potential. This potential causes a discharge whenever something metallic you are in contact with (the headphones in this case) touches earthed metal. The solution is to take your trousers off before mixing.

    Unfortunately, I don't have an equally simple solution for the hum problem. Do you get hum if you detatch all the input connections to the Presonus box (except mains) and just have the headphones plugged into it? If so, it indicates a problem inside the box. If not, then a ground loop is more likely.
  3. edaub1

    edaub1 Active Member

    Jun 10, 2009
    Thanks for your response. I guess ill do my mixing naked..I'm alright with that. Yes, when I bring the unit into other rooms by itself i still get a slight hum. Luckily I bought pro-coverage, so Im going to send it out. Maybe get a brand new one for free ;) (according to the guy at GC).
  4. Kurt Foster

    Kurt Foster Well-Known Member

    Jul 2, 2002
    77 Sunset Lane.
    try taking the power amp out of the rack ......:whistle:
  5. dvdhawk

    dvdhawk Well-Known Member

    Dec 18, 2008
    Western Pennsylvania, USA
    I don't know your location, but we're in the middle of winter here which means very dry, forced-air heat at my house. Running a humidifier helps keep static electricity to a minimum for me.
  6. paulears

    paulears Well-Known Member

    Feb 7, 2014
    Lowestoft - UK
    Home Page:
    I have a habit of sitting in the office chair and wheeling myself around, and the static pop when I touch ground is very annoying - in my case it's my chair is insulated from ground, but my feet on the carpet charge me up - often to many thousands of volts!

    The low level hum could be a ground loop, or it could simply be poor screening somewhere and maybe you have some poor shielding somewhere.

    Curing ground loops is a case of disconnecting everything and re-connecting in sequence. So connect the power amp to the speakers, and hopefully all is quiet, then connect the mixer, then all the other bits, and at some stage the hum will start - that's where you then need to investigate.
  7. John Alexander

    John Alexander Active Member

    Mar 8, 2015

    For the shocks, use an antistatic wristband. Follow the directions exactly. If you have to move across a room a lot, it can be a pain, but it cuts down on the swearing from getting a nasty static shock. Also, wearing 100% cotton helps as well. Ground loops, as the last poster pointed out, require you to be a detective. Good luck on both.

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