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  • Pentode Triode Switch

    I want to tinker with triode/pentode on a Fenderish amp I have. Do I just lift the suppressor grid from the plate line and ground it?

    Click image for larger version

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    In this forum everyone is entitled to my opinion.

  • #2
    Technically, the 6L6 does not have a 'supressor' grid.
    The beam forming plates act as a suppressor.
    It's really a Tetrode.

    You want to switch the Screen grid to the Plate.

    Click image for larger version

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    • #3
      Originally posted by Jazz P Bass View Post
      Technically, the 6L6 does not have a 'supressor' grid.
      The beam forming plates act as a suppressor.
      It's really a Tetrode.

      You want to switch the Screen grid to the Plate.

      [ATTACH=CONFIG]53574[/ATTACH]
      Careful of robrob's site, excellent graphics but often technically some 'room for improvement' (kudos to him for all his work with it, it's easy to criticise). It's generally recommended that the screen grid always be fed via a current limiting resistor; so the triode mode should include it, rather than switching it out.
      See https://el34world.com/charts/Schemat..._100w_2555.pdf
      My band:- http://www.youtube.com/user/RedwingBand

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      • #4
        Rob is a member here. He was around when he started it all, and was happy to change stuff that was wrong. I don't know if he still gets feedback; I do know he is making an effort to keep it all straight & accurate as he can. Si yeah, definite kudos for leaving the wealth up, even uf not perfect! If you play nice you might get an audience...

        I see him over on FarkBloop once in a while.

        Justin
        "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
        "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
        "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

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        • #5
          Thank you all for all info!
          In this forum everyone is entitled to my opinion.

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          • #6
            I had an EL84 amp that had a Triode/Pentode switch. (modded 1970 Traynor Guitar Mate III)

            It worked ok...

            As I recall, in triode mode it had a substantial drop in volume, as to be expected.

            Could get some nice crunch sounds in that mode.
            If it ain't broke I'll fix it until it is...
            I have just enough knowledge to be dangerous...

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