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Gain shaping with 300T (12AX7/AT7/AU7/AY7)

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  • Gain shaping with 300T (12AX7/AT7/AU7/AY7)

    My friend got 300T and want to experiment a bit with tubes to get different gain structure on CH2 that he wants to blend with CH1
    I am pretty new to 300T, never played one... I looked at schematic (attached) and quite confused with that. Assuming 12AT7s are driver tubes, would it be the classic way:

    V1 12AX7 = CH1?
    V2 12AX7 = CH2?

    If yes, is it possible to experiment with 12AY7 or AT7 (lower gain tubes) in V2 and see how overdrive would shape then? No risk problems with signal to driver tubes then?
    Attached Files

  • #2
    Thatīs the power amp, not the place to experiment with gain or tube rolling, leave as is.
    Juan Manuel Fahey

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    • #3
      I think you posted the wrong schematic. You mention V1 and V2 but they are not shown there.
      Originally posted by Enzo
      I have a sign in my shop that says, "Never think up reasons not to check something."


      Comment


      • #4
        Agree with both of the above. I'll add: Generally speaking, you can swap a 12AX7 with a 12AT7 or 12AY7 without issue.
        "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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        • #5
          I would however suggest you do not swap out the 12AT7 used as a driver.
          Education is what you're left with after you have forgotten what you have learned.

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          • #6
            Sorry, I posted wrong file! This was of course, power amp with 2x AX7 and 2x AT7 and 6x6550s
            This is the preamp (pictured here)

            So, V2A (labeled here) would be GAIN tube? So changing it to another type will leave clean channel 1 alone?Click image for larger version

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            • #7
              V2A and V2B offer a fair bit of gain for the dirt channel. Changing V2 should not affect Ch.1
              Originally posted by Enzo
              I have a sign in my shop that says, "Never think up reasons not to check something."


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              • #8
                Originally posted by g1 View Post
                V2A and V2B offer a fair bit of gain for the dirt channel. Changing V2 should not affect Ch.1
                Thanks!

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