Buzz goes away when I touch my amp

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by guiltless, Feb 16, 2012.

  1. guiltless

    guiltless Member

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    So I have my recent build out of the chassis right now an I discovered something as I was about to turn it off. When I touched the power switch, a slight buzz went away. This made me curious so I touched the outside of the chassis (not the inside) and the buzz went away again. It's similar to when you touch the strings on your guitar and the buzz disappears (which I have been too busy to cure in my guitar)

    This makes me nervous. I can deal with the guitar problem, but I don't want to mess with amp voltages not being grounded thoroughly when they are in excess of 460v!

    Any suggestions?
     
  2. timsmcm

    timsmcm Member

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    Are you shure that you have earth grounds in you house? In lots of older homes they had two prong outlets that have been changed out for 3 prong outlets, but no real ground. I live in a house now that has this problem.
     
  3. mcdes

    mcdes Member of no importance

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    Grounding issue of some sort for sure.
     
  4. EFK

    EFK Supporting Member

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    It's doing this because it is out of the cabinet. If you are standing there over your upturned chassis, it has no shielding. When you touch it, YOU are becoming the shielding so hum from RF interference lessens.

    On the other hand now, if it does this when you've installed it back in the cabinet with (I assume) some aluminum shielding in place, or *something* shielding the inputs (even a little soldered plate, like all the old Valco amps...), then you have a problem.
     
  5. Prairie Dawg

    Prairie Dawg Member

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    If you use aluminum tape to shield make sure you connect the sections so there's continuity, and run a ground wire from the chassis to the shielding. Aluminum tape is OK but aluminum screen is just as good. I did buy a 50 foot roll of aluminum flashing but I haven't tried it yet.
     
  6. guitarcapo

    guitarcapo Senior Member

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    First thing I would ask is how old is your house?
     
  7. guiltless

    guiltless Member

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    The apartment building was completely renovated from the studs out 5 years ago. But I am not certain that the wiring was completely upgraded so that could definitely be an issue.

    I do actually have a roll of Al Tape but the inside of the head cabinet is already shielded so at this point I will wait and see what happens when I put it back in the cab.
     

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