(!!!) (Recommended Single) 12AX7A RCA gray ribbed plates NOS 1971 (Gm=1600/1800 and 1.2/1.4ma)
(!!!) (Recommended Single) 12AX7A Sylvania NOS 1970's (Gm=2500/2800 and 2.2/2.7ma)
(!!!) (Recommended Single) 12AX7A Sylvania NOS 1970's (Gm=2600/3000)
(!!!) 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=ECC83 Mullard UK copper grid posts used/good 1965 (Gm=1400/1400)
(!!) (Good Value Single) 12AX7A GE NOS 1976 (0.9/1.3mA and Gm=1400/1800)
(!!) (Good Value) 12AX7A/7025 Sylvania used/good 1970's (Gm=2300/1900)
(!!) 12AX7A/7025 Sylvania branded RCA NOS 1970's (Gm=2100/2000)
