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My Build - Switch On Looms!

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  • #31
    Took the tubes back and guy swapped with no questions. The resistor now sits happily at 25V without catching fire. I also sussed the mismatch in plate voltages on the 12AX7. I read the plate 1 resistor as R20K, should have been 220K same as the other. So they are closer now but not identical.
    Amp is still very quiet though. Tried swapping the EF86 and 12AX7 out but with no change. Took some more measurements. (Man those 6V6's get HOT!) Still a bit of positive voltage on the pin 5's of the power tubes. But don't think that's the cause of it being so quiet.
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    • #32
      Wondering if I should be looking to see if the O/P tran is ok? Can't seem to find anything wrong in the wiring

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      • #33
        Bit of an update in case any one has any ideas.
        Removed the bypass caps. Made no difference except on the EF86 where it got quieter. Then removed the bass pot from the loop as it didn't seem to have any effect unlike the treble pot. This resulted in a rise in volume. But not much.

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        • #34
          Could anybody tell me how to test the OP Tran? I have a signal generator and access to a scope. Not quite sure how I should correctly wire the sig gen to the input and what sort of increase in signal I should expect.

          Thanks.

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