(!!!!!) (Recommended Single) ECC83=12AX7 Telefunken Germany smooth plates NOS 1963 (1.0/1.3ma and Gm=1500/1700)
(!!!!) (Best Value Single) 12AX7 Telefunken Germany smooth plates branded DYNACO like new 1964 (Gm=1600/1800 and 0.9/1.4ma)
(!!!!) (Recommended Single) 7199 RCA black plates NOS 1960's (12ma pentode / 6.6ma triode)
(!!!!) (Recommended Single) 7199 RCA black plates NOS 1960's (19.5ma pentode / 8ma triode)
(!!!) (Best RCA Single) 7199 RCA Black Plates NOS 1966 (14/7.2ma)
(!!!) (Single) 7199 RCA Black Plates NOS 1964 (10.2ma pentode, 12ma triode)
(!!!) (Single) 7199 RCA Black Plates NOS 1970 era (10.6/8.6ma)
(!!) (2nd Best Pair) 7199 Sylvania NOS 1960's and 1985 same build (12.5ma/9.6ma and 12.3/10.2ma) 1-3% matched
(!!) (Single) 7199 Sylvania NOS 1960's (11.8ma pentode, 7.8ma triode)
(!!) 7199 RCA Black Plates NOS around 1960 era (9/7.8ma)
12X4 GE GM Delco gray plates "D" getter NOS 1960 era (49/40 and 50/40)
12X4 GE gray plates "D" getter NOS 1960 (50/40 and 50/40)
12X4 RCA black plates "D" getter NOS 1950's faded printing (49/40 and 50/40)
12X4 RCA black plates "D" getter NOS 1956 (49/40 and 50/40)
12X4 Tungsol branded Raytheon black plates "D" getter NOS 1960 era (44/40 and 44/40)
12X4 Tungsol branded Raytheon black plates "D" getter NOS 1960 era (50/40 and 50/40)
7199 RCA Black Plates NOS 1963 (10.4/7.6ma)