(!) (MULLARD CLONE) 12AX7=ECC83 Matsushita Japan NOS 1960's (Gm=1600/1500 and 1.2/1.0ma) (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)
(!!!) (Best Value) 7025 Silvertone Hitachi Japan ribbed gray plates low hours/tests like new 1960's (Gm=1700/1800 and 1.2/1.4mA) (V1 guitar amp)
(!!!) 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)
(!!!) 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) 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)
(!!!) (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)
(!!!!) (Best Value Single) 12AX7 Telefunken Germany <> bottom smooth plates branded GAP/R Computor tube like new 1964 (Gm=1700/2000 and 1.1/1.5ma)
(!!!!) (Best Value Pair #1) 12AX7A RCA gray ribbed plates NOS 1967-1973 (best tone) (0.9/0.9ma and 0.9/1.1ma) (Fender)
(!!!) (Recommended Single) ECC83=12AX7 Mullard Webcor ribbed plates used/good 1962 (161 series) in white box (1.0/0.7ma and Gm=1600/1400)
(!!) (Best Value Pair) ECC83=12AX7 EI Yugo Telefunken NOS smooth plates clone rebranded Amperex and National (1.2/1.2ma and 1.2/1.3ma)
(!!!) (Good Value Single) 12AX7A RCA Magnavox ribbed plates used/good 1961 (Gm=1500/1900 and 0.8/1.3ma)
(!!!!) (Best Single 1958) 12AX7 GE tall gray ribbed plates "U" getter 1958 like new (Gm=1800/1800 and 1.3/1.3ma) 1% section balance
(!!!) (Good Single) 12AX7 Amperex Bugle Boy Holland "Long Plates" with "D" getter used/tests like new 1957 (Gm=1600/1700 and 1.0/1.2ma)
