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Tube life considerations. tt verses oxide

Posted by amnesiac (A) on August 7, 2017 at 05:17:49

Hi guys I love my amps and my tubes. I am planing my next main amp and tube life is on my mind. How many hours can I expect to get from tubes. Its important that I dont select a tube that is too costly because costs add up. Now I dont want to listen to crappy Chinese tubes while they are improving.

I read c3m tubes last 10000 hours thats 1.5 years at 18hours a day which is what my tv amp runs for. over 20 years thats 13 pairs of output tubes alone.

what output tubes last the longest?

I suspect my 10y in service currently have lasted at least that long.
I have worn out a pair of Chinese 300b but I have not worn out 10y yet.
I burnt pairs of used pt15 very quickly.
I was reading stc 1946 manual and it said thorated not to be confused with pure tungsten do not last any longer with reduced filament voltage and MUST NOT be run any less then 5% rated voltage.

I can imagine for oxide along with reduced bias filament voltage reduced a little would increase tube life.

has anyone got any ideas on what sort of tube life can be expected from the nos tubes below?

vintage dht radio tubes both nos and strong testing used(often all thats affordable)
o1a
26
71a oxide
45
2a3

tt radio
o1a
71a(early globe) new and good used

transmitting
10y 801a
811/809 in a2 operation? reduced life?
momentary or fast turn on radio tubes hy65/69 2c24 826
211 a2/ and at class A reduced 750volt and 1100 a1
845 at low voltage and 1100a1
the big eimac's at reduced voltage
4e27 4/125a 75 tl these would have to last well provide the plates where cherry red. I think I can answer this? in care and feeding your eimacs? I will try find that paper.
814 and 4e27 are on my short list(tubes bought)

audio pentodes triode wired
kt 44 66 88
6v6 6l6 el34 el84

finaly chinese and russian

2a3 300b
211/854
45/px4 eml kr etc

any opinions/suspicions on tube life appreciated

Edits: 08/07/17 08/07/17

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