(!!!!) (Best Overall Single) GZ37 Mullard UK NOS 1966 (52/40 and 52/40) 1% section balance
(!!!!) (Best Pair 1966) CV378=GZ37 Mullard NOS 1966 (51-51/40 x 2 tubes) 1% matched
(!!!!) (Best Pair) CV378=GZ37 Mullard NOS 1966 (50-51/40 x 2 tubes) 1% matched
(!!!!) (Best Single) CV378=GZ37 Mullard UK NOS 1966 (53/40 and 54/40)
(!!!!) (Best Single) CV378=GZ37 Mullard UK NOS 1967 (50/40 and 50/40) 1% section balance
(!!!!) (Best Value 1955) CV378=GZ37 Mullard UK "D" getter NOS 1955 (56/40 and 56/40)
(!!!!) (Recommended Single) CV378=GZ37 Mullard UK NOS 1967 (52/40 and 54/40) 1-3% section balance
(!!!!) (Recommended Single) GZ37 Mullard UK NOS 1967 (50/40 and 50/40)
(!!!!) (Single 1950's) 12BH7A RCA branded Westinghouse narrow black plates NOS "U" getter mid-1950's (10.6/7.4ma) (1st series made)
(!!!!) (Single 1955 era) 12BH7A RCA narrow black plates used/very good "U" getter halo 1955 era (8.6/10ma) (1st series made) (rare)
(!!!!) (Single) 12BH7A GE gray oval plates NOS mid-1960's (11.5/16ma)
(!!!!) (Single) 12BH7A Sylvania NOS gray oval plates NOS 1965 era (8.2/8.4ma) 1-3% section balance
(!!!) (Recommended Single) 12BH7A Westinghouse black ribbed plates "U" getter halo 1961 (8.5/10ma)
(!!!) 12BH7 GE Silvertone gray oval plates NOS "U" getter 1953 (8.2/8.0ma)
(!!!) 12BH7A RCA branded Zenith NOS 1970 era (10/13.2ma)
(!!) (Best Value Single) 12BH7A Hitachi Japan 1970's branded Westinghouse NOS 1984 (11.8/12.9ma) (McIntosh, Quicksilver, Art Audio, Wells)
(!!) (Good Value Pair) 12BH7A RCA gray plates used/good 1960's (10.4/82.ma and 9.4/9.5ma) (close Gm)
(!!) (Good Value Single) 12BH7A GE Daystrom gray oval plates low hours like new 1960's (9.2/9.0ma) (Same Gm)
(!!) (SINGLE 1953) 12BH7 GE NOS gray oval plates "U" getter 1953 NOS (9/12ma)
(!!) (Single) 12BH7 GE Delco gray oval plates "U" getter NOS 1950's (7ma/8ma) (Quicksilver, Wells, Doshi, McIntosh)
