(!!!) (Best Pair) 6BQ7A GE black plates "U" getter NOS 1957 (12.8/12.2ma and 11.0/11.6ma) (Highest mA and Gm)
(!) (SINGLE) 6BZ7=6BQ7A GE GM Delco "U" getter NOS 1950's (11.6/10ma)
(!!!) (Best Single) 6BQ7A GE gray plates U getter NOS 1962 (6.8/6.8ma) (1-2% section balance)
(!) 5BQ7A RCA black plates NOS 1964 (11.6/14.4ma)
5BQ7A GE Dumont gray plates "O" getter 1973 (12.8/8.2ma)
(!) (PAIR) 5BQ7A GE gray plates NOS large "U" getter halo 1961 -1964
6BK7B Philco by Sylvania NOS 1960 (13.2ma/15.2ma)
(!!!!!) (INFORMATION) 6N1 or 6N1P (Best Sounding Substitutes = 6BK7B, 6BQ7A, 6BZ7)
(!!!!!) (Best Value Pair) 6BQ7A RCA black plates NOS "D" getter 1958-1959 (7.6/9ma and 7/9.6ma)
(!!!) (Recommended Pair) 6BK7B Tungsol black plates NOS "O" getter 1960's (7.5/8.6ma and 8.2/9.4ma)
(!!!) (Recommended Pair) 6BK7B Tungsol black plates NOS "O" getter 1960 era (9.5/12ma and 9.8/10.5ma)
(!!!) (Recommended Pair) 6BK7B Tungsol gray plates NOS "O" getter 1960's (10/11ma and 10.6/13.2ma)
(!!!) (Recommended Single) 6BK7B Tungsol gray plates NOS 1960's (8.0/9.8ma) (great sub for 6N1P)
(!!!!) (Single) 6BK7B Tungsol branded RCA "U" getter 1957 (10/14ma)
(!!!!) (Best GE Single) 6BK7B GE gray plates NOS "U" getter 1974 (8.0/8.8ma)
(!!!!) (Best GE Single 1957) 6BK7A GE gray plates NOS "U" getter 1957 (9.8/10.8ma)
(!!!!) (Single) 6BK7B GE gray plates NOS "U" getter 1963 (6.2/5.4ma)
(!!!) 6BZ7 RCA black plates "U" getter NOS 1954 (9.6/12.2ma)
(!!!) (Best Single) 6BZ7 RCA black plates large "D" getter NOS 1957 (11.6/12.4ma)
(!!!!) (Best Value Pair) 6BQ7A RCA black plates NOS "D" and "U" getter 1957 (9/16ma and 9/14.5ma)
