Ground screw on amp chassis?

Discussion in 'Archived Threads 2001-2004' started by Sal Conigliaro, Mar 8, 2002.

  1. Sal Conigliaro

    Dec 11, 2001
    Likes Received:
    Is the ground screw on an amp's chassis for anything other than connecting to a turntable?

    I read that you can solve a ground loop problem by connecting

    a grounding wire from the amp's ground screw to either the metal box in the electrical outlet or the screw that holds the electrical outlet in the box (top & bottom screws)

    Is that true?

  2. brucek

    brucek Second Unit

    Dec 29, 1998
    Likes Received:

    The ground screw on the amp's chassis is already connected to the items you mention.

    In a three prong plug and wall receptacle, the center round conductor is the safety ground. The safety ground is for your protection if a fault inside a piece of your equipment causes the hot 120 volt line to contact the metal case. The safety ground will cause a breaker to trip, otherwise you'd get a shock if you touched the case.

    Inside the amp this safety ground is usually connected to an external screw for your convenience.

    It can be used as you've said for a turntable or any device you would like to bring to the same ground potential as your amp. Sometimes if you've got equipment plugged into different outlets, there can be a small potential difference between the grounds and this can cause a ground loop hum. Bonding these two grounds with an external wire from this screw can sometimes help, but usually just makes things worse.


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