(!) 6SN7GTB RCA low hours/like new "D" getter halo 1960's (9.2/9.6ma)
(!) 6SN7GTB Westinghouse USA gray plates "O" getter halo NOS 1961 (8.2/9.6ma)
(!) JAN-CLRV-6SN7WGTA GE Canada brown base NOS 1970 (7/10ma)
(!!!) 6SN7GTB Westinghouse black plates copper grid posts "D" getter 1950's (7.2/8.4ma)
(slightly microphonic) 6SN7GT Hytron NOS 1948 (7/8ma)
(slightly microphonic) 6SN7GTA GE NOS 1952 copper grid posts (7.4/10ma)
(!!!!) (Best Single) JAN-CHS-6SN7W Sylvania "SHORT BOTTLE" NOS 1945 in Admiral box (8.2/8.0ma) (1-3% section balance)
(slightly microphonic) JAN-CHS-6SN7W Sylvania "SHORT BOTTLE" used/good 1945 (7.0/7.6ma)
(!) 6SN7GT Westinghouse USA black plates NOS 1950 era (7.0/11.0ma)
(!!!!!) (Best Value Pair) 6SN7GTB GE NOS 1955-1964 same build (6.1/6.5ma and 6.0/6.3ma)
(!!!!) (Best Value Pair) 6SN7GTB GE NOS 1970 era (7.1/6.8ma and 7.2/7.2ma) (Schiit Freya)
(!) 6SN7GTB Westinghouse Canada black plates "O" getter halo NOS 1969 (8.2/8.6ma) (similar to RCA)
(Read Review) 6SN7GTB GE NOS 1968-1974 (Schiit)
(!!!!!) (Best Sylvania pair) JAN-CHS-6SN7WGT Sylvania chrome top NOS 1952 (7.6/7.8ma and 7.2/8.6ma) (low noise, detailed, good extension) (High Gm)
(!!!!) (Good Value Pair) 6SN7GTB GE NOS and like new 1960-1964 (7.0/7.8ma and 7.0/6.8ma)
(!!!) (Best Value Pair) 6SN7GTB GE low hours/like new 1955-1958 (8.2/9.0ma and 7.6/8.2ma) (Schiit, Ayon, Rogue) (close Gm)
6SN7GTA CBS NOS Black Ribbed Plates similar to RCA early 1950's (8.3/8.6ma)
6SN7GTB CBS black base black plates side-getter, the same shape as Sylvania 6SN7GTB used/good 1961 (7.5/8.0ma)
6SN7GTB RCA used good 1960's (6.4/8.2ma)
(!!!) (Best Single 1949) 6SN7GT RCA black plates coated glass NOS 1949 (9.4/9.8ma)