NOS tubes fall within the Gm characteristic range of an average tube, as published in the RCA RECEIVING TUBE MANUAL, which states “Individual tubes, like any manufactured product, may have characteristics that range above or below the values given.
(2) Amperex Bugle Boy 12AX7 ECC83 Treble Clef Matched Codes 1959 Tests NOS
(2) Amperex Bugle Boy 12AX7 ECC83 Treble Clef Vacuum Tubes | 1959 Production | Matched Codes I6I Δ9L/J. Tube 1 tests at 54/50 and tube 2 at 48/52 with 32 being the minimum score for a good tube (with 65% life remaining).