(!!!!) (Recommended Pair) ECC83=12AX7 Tungsram Hungary branded IEC Mullard NOS 1982 (1.5/1.6ma and 1.4/1.7ma)
(!!!!!) (Best Siemens Pair 1968) CV492=ECC83=12AX7 Siemens Halske Germany NOS 1968 1-2% matched (1.2/1.3ma and 1.2/1.3ma) (best in phono stages and high end preamps)
(!!!!!) (3rd Best Siemens Pair 1968) CV492=ECC83=12AX7 Siemens Halske Germany NOS 1968 1% matched (1.1/1.1ma and 1.1/1.1ma) (best in phono stages and high end preamps)
(!!!!!) (3rd Best Siemens Pair 1968) CV492=ECC83=12AX7 Siemens Halske Germany NOS 1968 1-2% matched (1.1/1.1ma and 1.1/1.2ma) (best in phono stages and high end preamps)
(!!!!) (Best Siemens Single) CV492=ECC83=12AX7 Siemens Halske NOS 1968 1% section balance (1.4/1.4ma) (Gm=1800/1600) (phono, mic, preamp)
(!!!!!) (Best Siemens Pair 1972) E83CC=12AX7 Siemens Halske Germany NOS triple mica 1972 printed in 1976 (1.0/1.3ma and 1.1/1.3ma) (best in phono stages and high end preamps)
(!!!!) (Best Siemens Single 1972) E83CC=12AX7 Siemens Halske NOS triple mica made 1972 printed 1976 (1.2/1.2ma) (Gm=1700/1700) 1% section balance
(!!!!!) (Recommended Pair) 12AX7=ECC83 Mullard UK ribbed plates NOS 1970-1974 (1.2/1.3ma and 1.2/1.1ma) (same Gm)
(!!!!) (Best Overall Single) CV4004=12AX7 Mullard box plates NOS 1971-1972 (Gm=1600/1700) (1.3/1.5ma)
(!!!!) (Recommended Single) CV4004=12AX7 Mullard box plates NOS 1971-1972 (Gm=1500/1500) (1.0/1.1ma)
(!!) (Best Value Single) 12AX7 EI Yugoslavia Smooth Plate TELEFUNKEN copy NOS 1979 (1.0/1.2ma and Gm=1800/1900)
(!!!!) (Recommended Pair) 12AX7=ECC83 Philips and Pope Holland NOS 1965-1967 (2.1/1.8ma and 1.6/2.1ma) (Highest mA and Gm)
(!!!!!) (Best Single 1963) CV492=12AX7 Mullard UK NOS 1963 (161 series) (1.3/1.3ma) 1% section balance
(!!!!) (Recommended Single 1955) 12AX7 BRIMAR England like new gray ribbed plates "D" getter 1955 (1.1/0.9ma) (Gm=1700/1500)
(!!!!) (Recommended Single 1959) 12AX7 BRIMAR BVA England like new gray ribbed plates large "O" getter 1959 (1.1/1.0ma) (Gm=1500/1600)
(!!!) 12AX7 BRIMAR England BVA ribbed plates used/good 1960's (0.9/1.1ma and Gm=1350/1500)
(!!!!) (Recommended Single 1957) 12AX7 BRIMAR England NOS gray ribbed plates "O" getter 1957 (1.3/1.2ma) (Gm=1700/1900)
(!!!!) (Good Value 1962) M8137=12AX7S Philips SQ France ribbed plates NOS 1962 (0.8/0.9ma and Gm=1350/1350) (Special Quality 12AX7)
(!!!!) (Good Value 1962) M8137=12AX7S Philips SQ France ribbed plates NOS 1962 (1.1/1.1ma and Gm=1550/1450) (Special Quality 12AX7)
(!!!!!) (Best Holland Pair 1967-1968) 12AX7=ECC83 Philips and Philips Miniwatt Holland ribbed plates "O" getter halo NOS 1967-1968 (1.3/1.5ma and 1.4/1.6ma) (close Gm)