12at7 ecc81 tube nos Mullard preamp tubes pair valve s same code square getter
2 tubes type ecc81 = 12at7 Mullard tube nos with box
tested with tube tester TV7 = 68/74 & 64/68 (reference good at 50/50)
tested also on Funke W19S = 11mA for each system for each tube ( reference good at 7mA)
same code I 1552 H4 for each tube
same inner structure
square getter welded
copper rods
wrinkled glass
coin base
old production
grey plates
with old carton boxes
original vintage vacuum tubes pre amplifier British made preamp valves old production