(slightly microphonic) 6201=12AT7 RCA black plates NOS 1976 (11/12.4ma)
12AT7=E81CC=6201 Siemens triple mica NOS 1971 (12/15.8ma)
12AT7WA=6201 GE NOS gray plates 1965 (7.8ma/10.6ma)
6201=12AT7 GE "5 STAR" used/good triple mica "U" getter halo, copper grid posts, gray plates, 1957 (6.2/7.8ma)
6201=12AT7WA RCA Black Plates "o" getter halo used/like new 1961 (8.6/7.8ma)
