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Ampeg PF-20T 60Hz grounding hum

Discussion in 'Amps and Cabs [BG]' started by focusbob, Mar 6, 2019.

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  1. Mar 6, 2019 #1
    focusbob

    focusbob

    Jan 28, 2019
    I just received my new Ampeg PF-20T and it has a loud 60Hz type hum that goes away when I touch my strings or other instrument metal pieces. I've tried various instruments to no avail. Is this a known issue? Is mine particularly defective? Thanks!
     
  2. Mar 6, 2019 #2
    agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    Try a different bass, this is a classic symptom of a bridge that's no longer bonded to the signal ground within the bass.

    You are operating your amp on a grounded power circuit?
     
  3. Mar 6, 2019 #3
    focusbob

    focusbob

    Jan 28, 2019
    I am (grounded power circuit). I have tried 5 basses and 2 guitars... (also, these instruments do not exhibit 60Hz hum with other amps).