What does it sound like if cathode follower/PI Tubes have died?

Discussion in 'The Workbench' started by Sandwell, Oct 18, 2019.

  1. Sandwell

    Sandwell New Member

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    The other day my Marshall DSL 50 started sounding weird, it basically sounds shrunken and a bit collapsed. I put in my spare set of output tubes but it sounded the same. The amount of gain hasn't changed so I'm thinking V1 and 2 are fine. Could the cathode follower or phase inverter have died? is this what it would sound like? I have EHX 12AX7s in all positions and I've just read that russian tubes arn't the best for the cathode tube...
    Cheers
     
  2. anitoli

    anitoli Well-Known Member

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    When in doubt, swap em' out. Tube exchange is one of the first and easiest trouble shooting tricks you do to isolate the problem.
     
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  3. RobS

    RobS Active Member

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    had a similar thing years back with my 2203. basically the 2nd pre amp tube had failed in my case (tung sol)
    sound was there but weak or collapsed as you describe

    changed the 2nd tube and all good again
     
  4. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    It could be a bad circuit board, look me up if you want to test the board....
     
  5. johan.b

    johan.b Well-Known Member

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    I'm with anitoli..
    .. there is a reason tubes, the most vulnerable parts of your amp, sits in sockets on the outside of the chassis and not soldered in, on the inside.
    J
     
  6. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    The circuit board plugs in, just like the tubes do...
    I would check that first considering.
     
  7. Sandwell

    Sandwell New Member

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    V2 in a 2203 is the cathode follower so I will swap that one out, thanks
     
  8. MarshallDog

    MarshallDog Well-Known Member Premium Member

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    The PI is the hardest working tube in the amp, it should be changed with the power tubes!
     
  9. Sandwell

    Sandwell New Member

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    I did not know this, thanks
     
  10. Sandwell

    Sandwell New Member

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    It was the cathode follower tube
     
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