(!!) (Good Value Single) 12AX7=ECC83 Telefunken Germany <> bottom ribbed plates used/very good 1960 era (Gm=1300/1400 and 1.1/1.1ma)

1 low noise tube) 12AX7=ECC83 Telefunken Germany <> bottom ribbed plates used/very good 1960 era in white box – no printing

Gm=1300 (1.1ma)

Gm=1400 (1.1ma)

Good used Gm range 1300-1500