If your tubes are in an amp not made in usa as in china, or other foreign country, you need to be aware that the power transformer maybe operating on 110vac instead of 120vac. In which case all the voltages in the amp will be almost 10% higher than the circuit was designed for. With 10% higher plate and filament voltages the tubes will be burning up at a rapid rate. Actually it is mandatory to check the filament and plate voltages of any tube amp to make sure they fall within the design specs.
Err--I dont think O/P meant a fully complete Amp from China--Just the Tubes from China....
A Chinese so-called, 'CV181' (which it isnt, a CV181 is a Ruggedised Military ECC32 from WWII times having amplification factor of 32 as opposed this Chinese 6SN7 clone having 17-20 )
-- will no where near last as well as an RCA 'Special-Red' 5692 (6SN7) expected life of 10,000 hours, or an original genuine British MOV/Mullard CV181 valve....
I seriously doubt any modern new produced Chinese tube could get even to half that....
Seriously, If you want a quality product, then NOS is the way forward, as IMHO, New Chinese are just OK,--no more than that-- Just OK......
--- They are Definitely NOT worth the stupid extra cost of them over and above a std. NOS example, they'll prolly manage 500-1000 hours or so, before showing age related issues....
Like everything, Depends how hard you run 'em as to how well they'll last, but one thing is certain, a Proper genuine NOS tube will last much better, and in some cases perform much better too, this has been my personal experience.
A Chinese so-called, 'CV181' (which it isnt, a CV181 is a Ruggedised Military ECC32 from WWII times having amplification factor of 32 as opposed this Chinese 6SN7 clone having 17-20 )
-- will no where near last as well as an RCA 'Special-Red' 5692 (6SN7) expected life of 10,000 hours, or an original genuine British MOV/Mullard CV181 valve....
I seriously doubt any modern new produced Chinese tube could get even to half that....
Seriously, If you want a quality product, then NOS is the way forward, as IMHO, New Chinese are just OK,--no more than that-- Just OK......
--- They are Definitely NOT worth the stupid extra cost of them over and above a std. NOS example, they'll prolly manage 500-1000 hours or so, before showing age related issues....
Like everything, Depends how hard you run 'em as to how well they'll last, but one thing is certain, a Proper genuine NOS tube will last much better, and in some cases perform much better too, this has been my personal experience.
A tube life span depends on if the amp are using soft start and separate switches for filaments and HV supplies.
5000 hours for small tubes is hard to find even in Russian military tubes(made to war, cost no object) let alone Chinese commercial tubes(made to profit);
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some say that the small signal tubes would last close to 10000 hours.
Tube Issues ? PrimaLuna USA
Technical Help :: Tube Basics and Frequently Asked Questions
How long is the life span of tube amp?
Secret to tube longevity--Don't Ever Turn Them Off, and use conservatively within their ratings, a NOS signal tube will last many years!
There's a tale of an AC/HL Triode used in the BBC. A single medium Mu tube.
It was discovered 80 Years After it had been installed, in some grubby basement quietly passing the World-Service feeds for all that time. It was in a rack long forgotten--until someone turned the rack off that is, to do some modernisation/alterations to the basement.
This tube was tested and still found to be 80% of its new ratings, after 80 years of continuous service...
Trouble with new Chinese produced tubes, the Materials used ain't as good/pure as those produced in the day, nor is the vacuum integrity as good, so no matter what you do, it will not last as well as a NOS tube. the QC isnt as strict, nor the testing as extensive, no matter What they claim--They just haven't the Knowledge.
For instance, the Nickel metal the cathode is made from Must be Absolutely Pure, free from silicon particularly and other impurities or the cathode emissive oxide coating becomes poisoned--from within--over time--NOT a damned thing you can do about that, this is a separate poisoning to that claimed by ion bombardment due to gas/excess voltage etc...
--I am lead to believe at Mullard in Blackburn, they specially refined the Nickel metal used for cathode sleeves themselves on site, as well as the various other metals and carbonates, even the glass they used for production was specially refined, tested, continual testing of each component metal etc.--in the day it really was a Massive place, almost a self contained town, even with its own power-station and gas plants--Thousands worked there, including a lot of very clever people, scientists and engineers...
--Youtube, Mullard Factory--There's a few (now rather scratchy) films about the place,--After watching, would you Really go buy a valve from China??
I can guarantee that No Chinese Co currently has the facilities and knowledge that the old masters such as Mullard had. Most of that knowledge has been totally lost as the guys themselves have died, many things were never written down, and that info which was documented is all propriety information anyway and gawd-knows where that is now--as we are talking 50-70 years ago these tubes were made--Lost forever, only the bottles remain.
Call me cynical--But Grant Fidelity are wanting to sell you the tubes--They'll Say they'll last to 5K, but say they only manage 1K, and get to 50% performance, at this time, long past their warranty.
At the end of the day--You'll buy Chinese, because some pundit (audiophool) in some magazine says they are cool, not because they Are actually any good--or not.....
There's a tale of an AC/HL Triode used in the BBC. A single medium Mu tube.
It was discovered 80 Years After it had been installed, in some grubby basement quietly passing the World-Service feeds for all that time. It was in a rack long forgotten--until someone turned the rack off that is, to do some modernisation/alterations to the basement.
This tube was tested and still found to be 80% of its new ratings, after 80 years of continuous service...
Trouble with new Chinese produced tubes, the Materials used ain't as good/pure as those produced in the day, nor is the vacuum integrity as good, so no matter what you do, it will not last as well as a NOS tube. the QC isnt as strict, nor the testing as extensive, no matter What they claim--They just haven't the Knowledge.
For instance, the Nickel metal the cathode is made from Must be Absolutely Pure, free from silicon particularly and other impurities or the cathode emissive oxide coating becomes poisoned--from within--over time--NOT a damned thing you can do about that, this is a separate poisoning to that claimed by ion bombardment due to gas/excess voltage etc...
--I am lead to believe at Mullard in Blackburn, they specially refined the Nickel metal used for cathode sleeves themselves on site, as well as the various other metals and carbonates, even the glass they used for production was specially refined, tested, continual testing of each component metal etc.--in the day it really was a Massive place, almost a self contained town, even with its own power-station and gas plants--Thousands worked there, including a lot of very clever people, scientists and engineers...
--Youtube, Mullard Factory--There's a few (now rather scratchy) films about the place,--After watching, would you Really go buy a valve from China??
I can guarantee that No Chinese Co currently has the facilities and knowledge that the old masters such as Mullard had. Most of that knowledge has been totally lost as the guys themselves have died, many things were never written down, and that info which was documented is all propriety information anyway and gawd-knows where that is now--as we are talking 50-70 years ago these tubes were made--Lost forever, only the bottles remain.
Call me cynical--But Grant Fidelity are wanting to sell you the tubes--They'll Say they'll last to 5K, but say they only manage 1K, and get to 50% performance, at this time, long past their warranty.
At the end of the day--You'll buy Chinese, because some pundit (audiophool) in some magazine says they are cool, not because they Are actually any good--or not.....
Practical observations?
Under what conditions.
What operating point?
What bias?
All amps are different!
This is the theory.
I develop and use old DHT (01a, 10, 26, 801, 841 etc.) based /pre/amps according to this theory...but my daily (2-3 hour/day) used 300B SE (CCS loaded D3a, source follower, EH300B) working for about 7-8 years ago contrary to this theory.
So, are you asking because you are thinking of buying some or because you have a problem with them not lasting?
I run eight of the Psvane CV181 TII tubes in my pimped Audio Innovations Second Audios. Ok, not the Shuguang Treasures but they are Chinese. Anyway I listen to them for about 8 hours per day for 5 days a week. They have been in the amps for about 3 months now and today I tested all 8 valves and they gave identical readings to the day they were installed. That's not many hours in the great scheme of things but it's all I can say so far.
So, come back and ask me the same question in a year or two . . . . . .
Oh, and they sound great.
For long lifespan the the big Radio transmission tubes, always have the filament with a little current in standby to be warm and to start is increasing to correct parameters and the third step is HV on. To switch-off the same, maybe for beam tubes is a good solution to have a filament PSU with low voltage and current to filaments to stand by, in my 211 mono block I use a separate transformer supply for filaments with separate switch, I hope to increment the lifespan of the psvane WE211 but I am thinking the standby with low current
Thanks for the links, I will read w/real interest.
Is not that I dont believe but 10K hours is a lot of years, it needs to be proven with users that take note of his use time on tubes.
If a GMI11 can last 25 years is a Sukhoi radar somewhat similar may be done w/chinese commercial consumer tubes (?).
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