(Manufacturer Mullard. Mullard Code I63 B5A4 / B5B4. Number 12AX7 ECC83. Pulled from a Hammond tube organ. T he Tube tested at 85% (2.03125 x 42.0 = 85.3 %). 3 2 = 65% of the value of a new tube. Tested Plate 1) 42.0 / 44.0 Plate 2) 42.0 / 44.0.
(Manufacturer Mullard. Mullard Code I63 B5A4 / B5B4. Number 12AX7 ECC83. Pulled from a Hammond tube organ. T he Tube tested at 85% (2.03125 x 42.0 = 85.3 %). 3 2 = 65% of the value of a new tube. Tested Plate 1) 42.0 / 44.0 Plate 2) 42.0 / 44.0.