There are two numbers because there are two tubes (triodes) per 6SN7. As to an earlier question of yours, the filiment usually does not burn out like a light bulb. What happens is the cathode coating slowly gets "poisoned" due to impurities at the time of manufacture. By the 1960s, they had figured out how to make tubes that would last for 100,000 hours. Think undersea cable amplifiers. But by then the transistor had taken over. Too bad for us tubeheads.
Tube Test Results
I've read descriptions of tubes for sale here claiming that claim the tubes for sale "Good" or "Excellent" on their teting machines. What does this mean?
If a tube is not "Excellent" does that mean that their is not as much life left but, sound quality is not affected or, tube life is deteriorating and sound is too.
I guess my ultimate question is, do tubes burn out like a light bulb - running strong until the filament burns up or, do they die like a battery - less and less energy over time?
Talking about specifically 6SN7GTs as an example - if that matters.
thanx
If a tube is not "Excellent" does that mean that their is not as much life left but, sound quality is not affected or, tube life is deteriorating and sound is too.
I guess my ultimate question is, do tubes burn out like a light bulb - running strong until the filament burns up or, do they die like a battery - less and less energy over time?
Talking about specifically 6SN7GTs as an example - if that matters.
thanx