(!!!!) (Best Value Pair) 12AX7=ECC83 Telefunken Germany <> bottom smooth plates used/good 1960's (0.8/0.8ma and 0.8/1.0ma)
(!!!!) (Single) E83CC=12AX7 Siemens Halske Germany NOS 1976 (0.7/0.9ma and Gm=1400/1600)
(!) (MULLARD CLONE) 12AX7=ECC83 Matsushita Japan NOS 1960's (Gm=1600/1500 and 1.2/1.0ma) (similar to Mullard)
(!) (MULLARD CLONE) 12AX7=ECC83 Matsushita Japan ribbed plates used/good 1960's (Gm=1450/1400 and 1.0/0.9ma) (similar to Mullard)
(!!!) 7025 RCA ribbed gray plates used/tests like new 1960's faded printing (Gm=1500/1500 and 1.1/0.9mA) (V1 guitar amp)
(!!!) 7025 RCA Beckman ribbed gray plates used/60% 1960's (Gm=1100/1300 and 0.5/0.7mA)
(!!!) 7025 RCA ribbed gray plates used/good 1960's faded printing (Gm=1400/1600 and 0.9/1.1mA) (V1 guitar amp)
(!!!) 7025 RCA ribbed gray plates used/good 1972 (Gm=1450/1400 and 0.9/0.8mA) (V1 guitar amp)
(!!!) (Best Value) 6681=12AX7 Hitachi Japan branded Amperex NOS 1970's (Gm=1400/1400 and 0.8/0.7ma)
(!!!) (BEST SYLVANIA PAIR) JAN-12AX7WA Sylvania NOS 1973 (1.7/1.6ma and 1.8/2.0ma)
(!!!) 12AX7=ECC83 Mullard UK "long plates" with "D" getter used/50-60% (0.6/0.7ma Gm=900/1000 - low Gm) (mC1 series)
(!!!!) (Best Single 1961) 12AX7=ECC83 Mullard UK ribbed plates NOS 1961 (161 Series) (1.1/1.1ma and Gm=1600/1700)
(!!) (Best Single 1966) ECC83=12AX7 Siemens Halske Germany NOS 1966 (162 Series) (Gm=1500/1600 and 1.0/1.1ma)
(!!!!) (Best Value 1965) 12AX7 Philips Miniwatt Holland like new 1965 (Gm=1900/1700 and 1.5/1.2ma)
(!!) 12AX7A/7025 Sylvania branded RCA NOS 1970's (Gm=2100/2000)
(!!!) (Good Value) 12AX7A/7025 GE NOS pinched plates 1976 (0.9/1.7ma and Gm=1500/2000)
(!!!!!) (Best Overall Single 1958) 12AX7=ECC83 Mullard UK "long plates" NOS 1958 (1.2/1.2ma) 1% section balance
(!!!!) (Good Value Pair 1960's) 12AX7A RCA gray ribbed plates NOS 1967 (best tone) (1.0/0.8ma and 1.0/0.8ma) (1-2% matched)
(!!!) (Good Value Single) 12AX7A RCA ribbed plates NOS 1974 (Gm=1600/1400, 1.1/0.8ma)
(!!!!) (Best Value Pair #1) 12AX7=ECC83 Telefunken Germany <> bottom branded GAP/R Computor tube <> bottom smooth plates used/good 1964 era (0.9/0.8ma and 1.0/0.8ma)
