6CS7 Tungsol NOS black plates 1960's (21/10ma) (internals like Sylvania)

6CS7 Tungsol NOS black plates 1960's

21ma Gm=4400

10ma Gm=2200

Tested on Amplitrex

Good Ma triode #1 = 20-25ma Good Gm = 4000-4500

Good Ma triode #2 = 10-11ma, Good Gm = 2000-2200

for:

Leben CS 600 integrated amp

Leben CS 660P power amp