(!!!!!) (Best Pair 1963) 12AX7=ECC83 Mullard UK made for Knight like new ribbed plates 1963 (161 series) (1.0/1.0ma and 0.9/1.0ma) (1-3% matched)
(!!!!!) (Best Single 1958) 12AX7=ECC83 Mullard UK "long plates" NOS 1958 (1.3/1.4ma)
(!!!!!) (Best Single 1963) CV492=12AX7 Mullard UK NOS 1963 (161 series) (1.3/1.3ma) 1% section balance
(!!!!!) (Best Single 1965) 12AX7 Mullard Bell & Howell UK NOS 1965 (1.3/1.2ma and Gm=1700/1600)
(!!!!!) (Best Value Single) 12AX7=ECC83 Mullard UK like new 1973 (1.8/1.1mA and Gm=2000/1600)
(!!!!!) (Recommended Pair) 12AX7=ECC83 Mullard UK ribbed plates NOS 1970-1974 (1.2/1.3ma and 1.2/1.1ma) (same Gm)
(!!!!) (Best Single 1961) 12AX7=ECC83 Mullard UK ribbed plates NOS 1961 (161 Series) (1.1/1.1ma and Gm=1600/1700)
(!!!) (Best Single) 12AX7A RCA gray ribbed plates NOS 1966 (1.0/1.0ma and Gm=1500/1500) 1% section balance
(!!!) (Good Value Single) 12AX7=ECC83 Mullard GE UK ribbed plates used/good 1966 (.8/.9ma and Gm=1450/1600)
(!!!) (Good Value) 12AX7A RCA gray ribbed plates "O" getter halo NOS 1973 (1.0/0.9mA and Gm=1400/1550)
(!!!) (Good Value) 12AX7A RCA gray ribbed plates "O" getter halo NOS 1974 (0.8/1.0mA and Gm=1350/1550) (Fender, McIntosh)
(!!!) (Recommended Single) 12AX7A Sylvania NOS 1970's (Gm=2500/2800 and 2.2/2.7ma)
(!!!) 12AX7 Sylvania 1960-1965 used/tests like new small mica flake inside tube (Gm=2400/2800)
(!!!) 12AX7=ECC83 Mullard UK "long plates" with "D" getter used/50-60% (0.6/0.7ma Gm=900/1000 - low Gm) (mC1 series)
(!!) (Best Value Single) 12AX7 EI Yugoslavia Smooth Plate TELEFUNKEN copy NOS 1979 (1.0/1.2ma and Gm=1800/1900)
(!!) (Best Value Single) 12AX7 EI Yugoslavia Smooth Plate TELEFUNKEN copy NOS 1979 (1.9/1.2ma and Gm=2400/1800)
(!!) (Best Value Single) 12AX7=ECC83 Mullard UK copper grid posts used/good 1965 (Gm=1400/1400)
(!!) (Nice Single) 12AX7 GE NOS pinched plates 1970 (1.0/1.3ma and Gm=1600/1800)
(!!) (Nice Single) 12AX7 GE NOS pinched plates 1970 (1.2/1.1ma and Gm=1800/1700)
(!!) 12AX7A Westinghouse pinched plates "square="D" getter" used/good 1950's (Gm=1400/1650)