(!!!) (Best Value Single) ECC83=12AX7 Siemens Halske Germany used/good 1960's faded date code (1.3/0.9ma and Gm=1700/1500)
(!!!!!) (Best Pair) 12AX7=ECC83 Philips Holland NOS 1966 and 1971 (1.8/1.7ma and 1.6/1.8ma) (Highest mA and Gm)
(!!!!) (Good Value Single) JRP-12AX7 Raytheon Black Plates NOS 1962 (Gm=1500/1700) (0.9/1.2ma)
(!!!!) (Good Value Single) JRP-12AX7 Raytheon Black Plates NOS 1962 (Gm=1300/1500) (0.7/1.0ma)
(!!!!) (Best Value Single) ECC83=12AX7 Tungsram Hungary NOS 1980 (Gm=1500/1800) (0.9/1.2ma)
(!!!!!) (Best Tungsram Single) ECC83=12AX7A Tungsram Hungary branded RCA NOS 1970's (Gm=2000/2300) (1.7/1.8ma) (Highest mA and Gm)
(!!!!!) (Recommended Single) ECC83=12AX7A Tungsram Hungary branded RCA NOS 1970's (Gm=1700/1900) (1.0/1.4ma)
(!!!!) (Best Pair #2 - best value) 12AX7 Telefunken Germany <> bottom ribbed plates used/very good 1960 era (0.9/1.0ma and 1.0/1.1ma) 1-5% matched (close Gm)
(!!!!!) (Best Value Pair) 12AX7=ECC83 Philips Holland like new 1968 same date codes (1.5/1.7ma and 1.7/1.8ma) (Highest mA and Gm) 1-3% matched
(!!!!) (Recommended Single) CV4004=12AX7 Mullard box plates NOS 1981 (Gm=1500/1600) (0.9/1.1ma)
(!!!!) (Recommended Single) CV4004=12AX7 Mullard box plates NOS 1981 (Gm=1500/1600) (0.9/1.2ma)
(!!!!!) (Best Pair) 12AX7=ECC83 Pope and Philips Holland NOS 1971-1972 (1.1/1.6ma and 1.2/1.7ma) (Same Gm)
(!!!) (Good Value) 12AX7A RCA gray ribbed plates "O" getter halo NOS 1973 (1.0/0.9mA and Gm=1400/1550)
(!!!!) (Best Pair) ECC83=12AX7 Tungsram Hungary branded IEC Mullard NOS 1982 (1.5/1.4ma and 1.5/1.4ma) 1% matched
(!!!!) (Slightly microphonic Single) CV4004=12AX7 Mullard box plates NOS 1981 (Gm=1400/1500) (0.8/1.1ma)
(!!!!) (Best Single) CV4004=12AX7 Mullard box plates NOS 1981 (Gm=1500/1600) (1.1/1.4ma)
(!!!) 7025 RCA ribbed gray plates used/good 1960's (Gm=1350/1600 and 0.6./1.1mA) (V1 guitar amp)
(!!!!) (Best Pair) ECC83=12AX7 Tungsram Hungary branded IEC Mullard NOS 1982 (1.3/1.6ma and 1.4/1.6ma) 1-3% matched (high Gm)
(!!!!) (Best Pair) ECC83=12AX7 Tungsram Hungary branded IEC Mullard NOS 1982 (1.4/1.4ma and 1.4/1.4ma) 1-2% matched
(!!!!) (Recommended Pair) ECC83=12AX7 Tungsram Hungary branded IEC Mullard NOS 1982 (1.5/1.6ma and 1.4/1.7ma)
