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Ampeg SVT-4 Pro 'always-on'-Humm in the preamp-section (NOT DI)

Discussion in 'Amps and Cabs [BG]' started by PA-Trick, Apr 12, 2017.


  1. PA-Trick

    PA-Trick

    Jan 14, 2017
    Hi all,
    welcome to my first thread :D

    My Ampeg SVT-4 Pro (about 10 years old) humms continuously, no matter the pre/master-volume or if there's a bass plugged in.
    It stops if I go directly into the Poweramp!
    (If only 1 cab is connected the right power amp has to be plugged-into to stop the humm of course)



    I have only found one old thread, possibly about this:
    Constant Ampeg SVT-4 Pro Hum. Any Ideas?
    where @Basslan had a similar problem, but the thread stops, before he tested circumventing the poweramp.

    I probably won't fix it myself, but I'd like to narrow down the problem as much as I can, before getting the amp to a local tech here in Austria.

    Thanks for your help
     
  2. BasturdBlaster

    BasturdBlaster

    Feb 19, 2012
    Crandon WI
    Maybe run some DeOxit in the effects loops and the pre/power loops? Maybe a preamp tube going bad? Sorry, that's all I got:)
     
    PA-Trick likes this.
  3. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    I'd say a preamp tube would be the first place to look.
     
    PA-Trick likes this.
  4. PA-Trick

    PA-Trick

    Jan 14, 2017
    Thank you, that's probably the easiest to start.
    I somehow dismissed the idea, because the pre-volume doesn't change the humm at all.
     
  5. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    Mar 2, 2021

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