(!!) (BEST PAIR) 6CS7 GE Canada black plates NOS 1964-1970 (20/11ma and 20.6/10ma)

1 pair) 6CS7 GE Canada black plates NOS 1964-1970 - same build as Sylvania

1 tube) 20ma Gm=4800 and 11ma Gm=2300 (HC) 1970 branded GE

1 tube) 20.6ma Gm=4800 and 10ma Gm=2200 branded Philco 1964

Good Ma triode #1 = 20-25ma, Good Gm = 4000-5000

Good Ma triode #2 = 10-12ma Good Gm = 2000-2400 

for:

Leben CS 600 integrated amp
Leben CS 660P power amp