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Adequate PT for 2x7591, 2x12AX7

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  • Adequate PT for 2x7591, 2x12AX7

    Im currently working on a custom build, sort of a trem-less 6G3 with 7591 outputs. Tube lineup is 2x12AX7, and 2x7591 running at about 90%.

    I have a PT I purchased from Weber with a 100mA rating. Will this be sufficient? 90% of 7591 at 350V gives me about 98mA between the two, and about 1-2mA per 12AX7. I could be sitting right at the rating, or a touch over. Any concerns?

  • #2
    WRT the PT I prefere to be AT LEAST 50% over rated. Some older guitar amp PT's were rated right at their usage current BUT had enough safety margin (wind gauge, insulation, etc) to take being run flat out all the time. I can't say that about the Weber. The end result is another variant of the sag effect. It's good for some types of circuits and specific tones but not for others. So with this in mind it also depends on the sort of tone your after. If it were my project I would hold off until I could get a bigger PT.
    "Take two placebos, works twice as well." Enzo

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "If you're not interested in opinions and the experience of others, why even start a thread?
    You can't just expect consent." Helmholtz

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    • #3
      Or use 6V6 output tubes as per the original 6G3 (providing you have suitable output tranny). Still not quite at Chucks recommended 50% over but enough over that your power tranny will cope fine.
      There is a reason that folk have been using Push Pull 6V6 for guitar amps almost fore-ever. That reason being that they sound damn fine.
      Cheers,
      Ian

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