Marshall Origin 50h Static Noise

Discussion in 'Marshall Amps' started by cgtrman, Nov 7, 2019 at 10:22 PM.

  1. cgtrman

    cgtrman Member

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    This amp might be my fave amp of all time, but I have a recurring issue. When I first power it up, there is 20-30 seconds of static and white noise regardless of anything connected to the input. It will die out and not return until my next power-up.

    A friend suspects a plate resistor might be to blame. Im hoping a preamp tube is the culprit. Any recommendations?
     
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  2. South Park

    South Park Well-Known Member

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    It’s things just powering up . Avery amp is a little different. It is what tubes do
     
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  3. cgtrman

    cgtrman Member

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    Changing power tubes wont fix it?
     
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  4. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    This is not normal, and it is not " what tubes should do."
    Replace the preamp tubes one at a time with a new 12AX7 and re-test the amp every time you swap one out w/ the new tube.
    If there is a bad tube you will find it.
    Most common cause of crackle in guitar amps is the preamp tubes. (it's usually one tube that does it)

    2. If the sockets contacts get oxidized it can also cause this to happen.
    A small amount of Deoxit G100 in the socket contacts will cure that problem.

    3. There is no reason to imagine that this is caused by a resistor.
    You need to find evidence before you reach that conclusion.
    Repairing guitar amps by guessing / random parts replacement generally gets you nowhere.
    It is "possible," but more commonly it's a preamp tube that's causing it.
    And I say this based on long term experience not guessing.

    4. Plug a guitar cable between send and return of the effects loop. Then re-test the amp.
     
  5. MarshallDog

    MarshallDog Well-Known Member Premium Member

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    Try preamp tubes first. I had this happen before to more than one amp and it was a preamp tube. Good luck!
     
  6. Phony iommi

    Phony iommi Well-Known Member

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    Not to divert the op here, but what diagnostics does plugging a cable into the send and return of the fx loop provide? What should happen when you do it?
     
  7. Mitchell Pearrow

    Mitchell Pearrow Well-Known Member

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    What was said before me, and check that your volume is on 0, when you power up!
    Cheers Mitch
     
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  8. cgtrman

    cgtrman Member

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    Thanks for all the great feedback and recommendations. I will start w swapping preamp tubes one at a time.
     
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  9. Mitchell Pearrow

    Mitchell Pearrow Well-Known Member

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    On my lead 100 mosfet it does away with volume swells.
     
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  10. cgtrman

    cgtrman Member

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    Would a preamp tube exhibit statis and white noise as it warms up, then go away?
     
  11. Mitchell Pearrow

    Mitchell Pearrow Well-Known Member

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    Good question, and I cannot answer it !!
     
  12. Arc Anjil

    Arc Anjil Active Member

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    My O50h does that hissing noise on power up/warm-up, too. Only on the 50 watt setting, though, not the 10 watt. I've rolled the pre-amp tubes and nothing has changed.

    Once warmed up it's all good.
     
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  13. cgtrman

    cgtrman Member

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    Interesting. Mine occurs on all three pwr settings.
     
  14. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    Now you are on the path to enlightenment.
     
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  15. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    Did you bypass the effects loop w/ a patch cable?
     
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  16. cgtrman

    cgtrman Member

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    I will be able to do that tonight along with preamp swaps. W fx loop test, do I need to plugin footsw cause I never use the fx loop?
     
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  17. cgtrman

    cgtrman Member

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    I never use the fx loop. I place a jumper in fx loop and the noise and static are the same. What is the purpose of that test?
     
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  18. cgtrman

    cgtrman Member

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    I replaced each preamp tube one at a time, no change. I will replace power tubes tomorrow.

    One more clue: it makes static and intermittent white noise w master vol at zero.
     
    Last edited: Nov 8, 2019 at 10:59 PM
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  19. Mitchell Pearrow

    Mitchell Pearrow Well-Known Member

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    I am sorry for your troubles with your amp brother, I am no tech, but my 2 Origin 50H’s have had no problems whatsoever.
    I do hope you’re able to get this corrected.
    Mitch
     
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  20. Arc Anjil

    Arc Anjil Active Member

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    No. It happens with or without using the loop and footpedal connected.
     
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