6sn7 b65 tube Marconi Made in Italy preamp tubes valve matched pair 6sn7gt vintage 1950's 

two tubes = 2 pieces = two valves = pair of tubes 

Marconi made in Italy , tested strong tubes tv7 tube tester 

test results 90/94 ; 94/102 (reference good at 50/50) 
reference of 100% = 80/80 

black base 
square getter 
black plate ribbed
oldest production 1950's 

rare vintage tubes for pre amplifier stage audio 

Double triode
Socket Octal K8A
Filament Heater Vf 6.3 Volt / If 0.6 Ampere / Indirect / Parallel, ~ = (AC/DC)

The 6SN7 was used as an audio amplifier in the 1940-1955 period, usually in the driver stages of power amps.
The designer of the famous Williamson amplifier, one of the first true high-fidelity designs, suggested use of the 6SN7 (or B65) in his 1949 revision since it is similar to the original circuit's L63 (= 6J5 ) British single triodes, four of which were used in each channel of his 1947 circuit. VERY RARE TUBES VALVES FOR PRE AMPLIFIER PREAM DRIVER

how do they sound ?

6sn7 Marconi are super charming and seductive.. super nice woody cellos and violins, elegant tubes 

box 155