I guess it’s aquestiin which can not be answered straight, but let’s assume we have a tube amplifier, which stand perfectly, enough air for ventilation, no direct sun, is not been moved if it’s hot and so on - what would be the general lifetime of tubes? I mean old light bulbs could hold forever, the newer ones we know where made to be replaced after certain amount of hours.
So if I have my tube amplifier running 5 hours a day, it should be a problem.... also all tubes I am have can be easily replaced... it’s just a question of interest.
So if I have my tube amplifier running 5 hours a day, it should be a problem.... also all tubes I am have can be easily replaced... it’s just a question of interest.
Depends on how conservatively the circuit was designed, especially the power dissipation of the tubes.
There are reports WE300B from WW2 lasted around 40.000 hours, today crap 300B last 700 hours, a shame.
"Small signal tubes" that is preamp drivers etc will last for 5000-10000h
powertubes less, typically 2000-5000h depending on amp
There is a book on this subject: Getting the most out of vacuum tubes, by Robert B.Tomer, published in 1960. The pdf is easily available on Internet. From the preface: "Informed scientists and engineers have frequently stated that the life of a vacuum tube in normal service should exceed 5000 or even 10000 hours. The fact that some of them do not last this long is well known". The book has 100+ pages on tube failure modes and their mitigations.
On a guitar tube amp, it is normal to replace the output tubes after 1000 hours. At the opposite extreme, Tektronix scopes made in the '50 often still have the factory tube complement.
On a guitar tube amp, it is normal to replace the output tubes after 1000 hours. At the opposite extreme, Tektronix scopes made in the '50 often still have the factory tube complement.
Well KT88,6SN7; 101D .... but have a rough idea know.
But then how is it possible for WE300b to have 40.000 hours ... very interesting makes roughly 4.5 years with 24 hours daily - wow!
But then how is it possible for WE300b to have 40.000 hours ... very interesting makes roughly 4.5 years with 24 hours daily - wow!
I have this book in paper and PDF, it was writen on a time when tubas are made to last, long before the ''hi-fi'' commercial tubes, which glass is under 1mm and net weight for a 300B is 100 grams or less.
As a service engineer from back in the valve days it mostly depends on the specific use of the valve - in all equipment, TV's, amplifiers, tape recorders etc. there were also specific valve uses that never ever failed. Generally these would be the small signal valves, most failures would be the output valves or rectifiers.
Do you think even back then planned obsolescence played a role?
Or just wear and tear?
I think it was mostly wear and tear, and designing circuits using valves close to their maximum limits - like any power devices built down to a really.
In itself this does not say anything.
How many hours have the tubes been operating ?
This is going back a decade or more....I believe the KR was/is a handmade brand emanating from the Slovak or E European region, (others can correct me on this) as I remember this handmade highend tube appearing in an audio magazine article.
It does seem a bit unfair to claim a tube life span from a custom made, away from the standard production from large Vendors. I say this because my 6550 New Ed TungSols got emission sloppy on the 2500 hrs point, loaded with 75mA Iq at 400V. Raw Deal !
rich
I installed an hour meter when i built my VTA-70. That's why i know that the JJ-6550
i use has 3580h on them, and they still holds bias and sounds fine.
i use has 3580h on them, and they still holds bias and sounds fine.
For most of the incandescent bulb era the lifetime was set to be 1000 hours, by an agreement between the manufacturers. Modern bulbs (e.g. CFL, LED) may last anything between 10's of hours and 10's of thousands of hours, depending on quality.acidnoid said:
- Status
- Not open for further replies.