Tubes question

[Jnorth1178]

What is the approx life of a power tube? And, how can one tell if a tube is failing? Do they gradually lose their sharpness and sensitivity or do they go out like a light bulb -- or both? JNorth

[Hdale85]

The sound changes quite a bit as a tube gets older. It's not quite like a light bulb. You would probably notice it and change it before the tube ever actually fails completely. As for life span I think its sort of random..... I think its a good while though. Depending on use I would say you could go on a set of tubes for maybe a year? Preamps its a lot better you don't have to change those very often at all.

[Kevin P]

Tubes have different "modes" of failure. They can wear out gradually and lose sound quality/clarity. They could start getting scratchy/staticky sounding. Or (rarely), a filament can burn out and the the tube goes dead like a light bulb.

How long they last depends on how hard they're driven. Preamp tubes tend to last longer than power tubes.

[Coconutout]

i have a tube preamp and i was not aware that tube sq degrades over time. that might explain why the telefunken i bought a while ago weren't that immediately impressive when i first installed them. it was only marginally better than sylvanias that it replaced.

[twitch54]

As the others have said...input and driver tubes last upwards of 10,000hrs. Whereas Output/power tubes usually a Quarter to a Third of that, alot depends how "Hot" they are being run (level of bias).

[Hdale85]

Yeah and tubes do have a breakin time as well so when you first buy them they don't sound as good as after you put a few hours on them.

[Boombox]

What is the approx life of a power tube?

+/-1.5 - 2years if you listen about 5hours/week.....loud!!

And, how can one tell if a tube is failing?

When one of my power tubes went or started fading I noticed that the one side (left e.g) was softer than the other.....swapping the tubes made the other side softer (e.g right) and also, I noticed it first with my imaging, then it sounded as if my tweeters were damaged....or blown...hope that helps