(!!!) (Recommended Pair) 6BK7B Tungsol black plates NOS "O" getter 1960's (7.5/8.6ma and 8.2/9.4ma)
(!!!) (Recommended Pair) 6BK7B Tungsol gray plates NOS "O" getter 1960's (10/11ma and 10.6/13.2ma)
(!!!) (Recommended Pair) 6BQ7A RCA black plates NOS 1962-1972 same build (9.5/11.5ma and 9.2/11ma)
(!!!) (Recommended Single) 6BK7A Tungsol black plates NOS "U" getter 1956 (8.6/9.6ma) (great sub for 6N1P)
(!!!) (Recommended Single) 6BK7B Tungsol gray plates NOS 1960's (8.0/9.8ma) (great sub for 6N1P)
(!!!) 6BQ7A RCA black plates NOS 1970 era (14.0/15.2ma)
(!!!) 6BZ7 RCA black plates "U" getter NOS 1954 (9.6/12.2ma)
(!!!) 6BZ7 RCA black plates large "D" getter NOS 1957 (10.4/11.0ma)
(!!!) 6BZ7 RCA black plates large "D" getter NOS 1957 (11.6/12.4ma)
(!!!) 6EM7 IEC Servicemaster by Hitachi Japan NOS 1968 (1.1ma and 47.5ma)
(!!) (#1 5687 Tungsol used 1950's) 5687 Tungsol rebranded IBM bronze plates "U" getter used/very good late 1950's (32.5/39ma)
(!!) (#1 5687 Tungsol used 1961) 5687WA Tungsol bronze plates "O" getter halo used/very good 1961 (33.4/34.8ma)
(!!) (2nd Best Single) E182CC=7119 Dumont Holland NOS "O" getter halo 1966 (34ma/44ma)
(!!) (Best Single) 13EM7 RCA coin-base black plates NOS 1970's (2.7/47.2ma)
(!!) (Best Single) 6EM7 RCA black plates NOS 1969 (2.9ma and 53ma)
(!!) 13EM7 RCA black base black plates NOS 1968 (2.0ma/28ma)
(!!) 6EA7 Sylvania NOS 1960 era (2.1/43ma)
(!!) 6EA7=6EM7 Sylvania Zenith coin-base NOS 1970's (1.8/65ma)
(!!) 6EM7 Sylvania NOS 1960 era (1.5/55ma)
(!!) JTL-5687WA Tungsol bronze plates "O" getter used/good 1958 (30/30.5ma)