Tube Swap Question

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by GuitarGuy3, Sep 10, 2019.

  1. GuitarGuy3

    GuitarGuy3 Member

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    Can you swap out 12AX7B tubes for 12AX7A tubes without biasing the amp? I know nothing about the tech side of amps.
     
  2. Dan40

    Dan40 Supporting Member

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    No biasing required when swapping preamp tubes.
     
    gunslinger likes this.
  3. GuitarGuy3

    GuitarGuy3 Member

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    Thanks! I have a newer Bogner Shiva 20th that is dropping in volume when it gets bumped. When I hit it again with my hand the volume comes back. My first thought is preamp tube issue but I really have no idea?
     
  4. HotBluePlates

    HotBluePlates Member

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    Something has a poor connection, and is working/not-working when bumped.

    It could literally be any connection in the amp. A thorough visual inspection inside & out, and maybe poking with an insulated tool will probably turn up where the bum connection is.
     
    Last edited: Sep 11, 2019 at 12:44 AM
    Glitch Magnet, pdf64 and oneblackened like this.

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