(!) (slightly microphonic) JAN-CRC-6SL7GT RCA NOS black plates 1951 tilted glass (2.0/2.2ma)
(!) 6SL7GT RCA burgundy base NOS 1951 (1.7/1.8ma)
5691 RCA Red Base Black Plates used 1948 (2.2/2.4ma) (Gm=62% and 75%)
6SL7GT Brimar NOS black base black plates 1950's (2.2/2.4ma) (slightly microphonic)
