(!!!) (Good Value) 12AX7 RCA "long gray plates" with "D" getter used/good 1960 good printing (0.6/0.7mA and Gm=1400/1500)
(!!!) (Recommended Single) 12AX7 RCA "tall gray plates" and "D" getter halo branded Raytheon used/good 1950's (Gm=1900/2100) (1.3/1.7ma)
(!!!!) (Holland single 1958) ECC83=12AX7 Triotron Holland "long plates" with "D" getter halo like new 1957 (1.1/1.2ma and Gm=1700/1700)
(!!!!!) (2nd Best Single 1958) 12AX7=ECC83 Mullard UK "long plates" NOS 1958 (1.3/1.4ma) (f91 series)
(!!!!) (Good Value Single) ECC83=12AX7 Amperex Bugle Boy Holland "long plates" and "D" getter used/good 1958 (1.1/1.1ma and Gm=1350/1350) 1% section balance
ECC83=12AX7 Mullard UK BVA long plates "O" getter like new 1958 (f91 series) (1.2/1.2ma)
(!!!) 12AX7=ECC83 Mullard UK "long plates" with "D" getter used/50-60% (0.6/0.7ma Gm=900/1000 - low Gm) (mC1 series)
