EL84 conversion to EL34

Discussion in 'The Workbench' started by Marcomel79, Oct 6, 2021.

  1. Marcomel79

    Marcomel79 Well-Known Member

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    hi fellow marshall maniacs, i was thinking about the possibility to change my amp from el84 to el34 (hence the title). is it an easy fix or do i have to revolutionize my whole amp? ill attach a schematic of the amp. btw its an 18W plexi-ish clone.

    Untitled.png D9D4F09F-DF0B-4944-ABBD-26520E562B1E.jpg
     
  2. Pete Farrington

    Pete Farrington Well-Known Member

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    It seems unlikely that a PT intended for an EL84 amp will cope with the heater current that EL34 will pull?
     
  3. Matthews Guitars

    Matthews Guitars Well-Known Member

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    Starting with changing both transformers and doing chassis surgery to remove the 9 pin tube sockets and install larger 8 pin octal sockets...after that it's fairly easy.
     
  4. Marcomel79

    Marcomel79 Well-Known Member

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  5. Matthews Guitars

    Matthews Guitars Well-Known Member

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    Leave well enough alone. Buy another amp if you want EL34s. That is my advice.
     
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  6. Marcomel79

    Marcomel79 Well-Known Member

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    Yeah. The chase for the ultimate tone never ends, and i love my amp. Dont fix it if it aint broke..
     
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  7. Pete Farrington

    Pete Farrington Well-Known Member

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    Between the 2 heater windings, it’s doable.
    What were you planning to do about the OT? I suppose it’s got an 8k primary? Same as a JTM45 Drake 784-103 :idea:
     
    Last edited: Oct 6, 2021
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  8. william vogel

    william vogel Well-Known Member Gold Supporting Member

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    You could always put 5881’s, 6v6’s. The power transformer being 100mA rated would not work very well with a typical 3.5k el34 output transformer but with 8k it’ll work with any of the octal tubes. It’s capable of the heater current utilizing both windings. You’ll have to use an artificial center tap for the one 6.3 volt. I’d skip the cathode bias and build a bias supply to allow easy swap for different octal tubes.
     
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  9. Marcomel79

    Marcomel79 Well-Known Member

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    i was planning to hear how much work it was before doing anything. I mean i love the amp the way it is, but it seems everybody agrees the EL34 are a bit warmer sounding than EL84... gonna have to think about it for a sec..
     
  10. mickeydg5

    mickeydg5 Well-Known Member

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    Many like EL84 for certain qualities as others like EL34 for certain qualities.

    It is a preference.

    I myself would actually like to try 6V6.
     
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  11. Marcomel79

    Marcomel79 Well-Known Member

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    Actually its nice with the early breakup of the el84's and they have a good bite. That means i need to build one with EL34's to try both..
     

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