[nichifanlema]

I was wondering....like on ebay, you can find lots of NOS and used tubes.

Is it okay to buy the used tubes with good testing? Or is it a good idea to strictly stick with the NOS tubes?

And is used but good testing (say, 90%?) tube worth of purchasing?

 

[Carl]

Sure it is. Sometimes you can find great deals on mildly used tubes, too. The only thing to factor in is that the tube will have a shorter life expectancy.

 

[nichifanlema]

Quote:

Originally Posted by Carl Sure it is. Sometimes you can find great deals on mildly used tubes, too. The only thing to factor in is that the tube will have a shorter life expectancy.

Hmm. what's the overall life expectancy of the tube? and if I buy used (at 90% testing rate) how would that be converted into real time? I mean like for example 10000 hours less than NOS tube?


Oh, and will the fact that the tube was used have any effect on the sound itself?

 

[003]

NEW audio tubes generally only last 2000-5000 hours. But you can run into oddballs that will last longer or shorter.

 

[nichifanlema]

Quote:

Originally Posted by 003 NEW audio tubes generally only last 2000-5000 hours. But you can run into oddballs that will last longer or shorter.

Do you mean NEW audio tubes by NOS tubes or Newly produced tubes?

 

[3x331m]

When I had my first tube amp, I had the same question about the life expectancy of tubes. I spent hours reading on tubes, searching for answers, but I ended up with the same question.

I had to settle myself with a theory that tube are just like light bulbs, and I might not find them last as long as the marketing numbers. I just keep a set of spare ready, just like how I stock up spare light bulbs.

 

[nichifanlema]

Quote:

Originally Posted by 3x331m When I had my first tube amp, I had the same question about the life expectancy of tubes. I spent hours reading on tubes, searching for answers, but I ended up with the same question. I had to settle myself with a theory that tube are just like light bulbs, and I might not find them last as long as the marketing numbers. I just keep a set of spare ready, just like how I stock up spare light bulbs.

so...when do you know it's time to replace the tube?

 

[003]

Quote:

Originally Posted by nichifanlema Do you mean NEW audio tubes by NOS tubes or Newly produced tubes?

NOS might last a little longer due to better quality vacuum, but not by much, and in some cases not at all.

 

[3x331m]

Quote:

Originally Posted by nichifanlema so...when do you know it's time to replace the tube?

I have multiple amp(s) and use only new/NOS or tubes tested as new or better. Personally, I did not have chance to see the condition of a dead/blown tube. However, I had one of the tube which has become more microphonic over time. I guess this particular tube is degrading/dying on me.

I've seen other posts in which other Head-fiers have described the dying tube condition very well (ie. glowing, extreme noise...etc). You might want to do some search on this topic.

 

[GotNoRice]

Quote:

Originally Posted by 003 NEW audio tubes generally only last 2000-5000 hours. But you can run into oddballs that will last longer or shorter.

That's only 3-6months of constant usage, which is somewhat common as people leave it on all the time rather than have to wait for the warm-up. Are you sure those are typical figures?

 

[sacd lover]

Quote:

Originally Posted by GotNoRice That's only 3-6months of constant usage, which is somewhat common as people leave it on all the time rather than have to wait for the warm-up. Are you sure those are typical figures?

Many Nos small signal tubes have 10,000 hour life expectancies. New production tubes dont last nearly as long. Buying "tests new" used tubes is a risky proposition. There is a reason the tubes were pulled from use .... noise, microphonics, channel imbalance etc... these tubes can test fine on a tester and be junk in actual use.

Unless you have a tube tester to verify the tube is as stated you will get burnt with junk tubes at some point. Besides the issue of good testing tubes that have other performance issues .... you will eventually get tubes that just dont test as advertised. The best bet is to buy tubes from a reputable dealer that actually does test them and that guarentees their performance with a warranty to replace or refund if the tube is bad.

 

[drarthurwells]

I would only add to SACD lover's comments that NOS tubes may not be truly new.

I have purchased some NOS from reputable dealers that tested slightly below some of my used tube purchases of the same tube.

Not saying for sure the NOS tube was not new as it is possible for a used tube to test stronger than the same tube that is new.

 

[tkam]

Quote:

Originally Posted by GotNoRice That's only 3-6months of constant usage, which is somewhat common as people leave it on all the time rather than have to wait for the warm-up. Are you sure those are typical figures?

Tube amps should never be left on all the time. I'd say for small signal tubes (6sn7, 6dj8, 12ax7) 4000-10000 hours is pretty accurate. Depends a lot on how hard the tubes are pushed though. Power tubes like el34, kt88, etc have much shorter lifespans 2000-3000 hours usually.