For sale is a rare GE 12DM7 tube which is a low noise and microphonic 12AX7 variant.

Calibrated TV-7 A/U tester (Dan Nelson)

Minimum value: 32/32

Tube tested: 38/38

Note: the tube tests lower then average but higher then 65% which is the the minimum value for my tester at 32/32. I would say the tube has about 70% of its life left. I used 12AX7 Mullard tubes in my Scott LK-72 that tested 28/28 (below the minimum) for about 5 years and they tested the same as when I first stated using them so this tube is still good and will last in a properly biased circuit.