Valve lifespan question...

[Barrymagrec]

On the point of rectifiers, all valve rectifiers give a soft star, the difference between directly heated types such as 5Y3, 5U4, 5R4, U50, U52 and indirectly heated types such as GZ32, GZ34, EZ80/81, 5Z4, 54KU is that directly heated types come up within a second or two putting a surge voltage on the reservoir caps whereas indirectly heated types take much longer to warmup so that by the time they can supply current the other valves in the amplifier are also warm and able to conduct so preventing the surge.

Of course directly heated output triodes such as PX5 ,PX25 and 300B also warm up very quickly so a directly heated rectifier is less of a problem.

 

[Mike Reed]

Most push-pull valve amplifiers are running in a rich class AB, so thrashing them does increase power dissipation and shorten life.

Taught me something, as I thought the vast majority of valve amps were class A entirely. Does longevity not depend also upon the type of valve (as opposed to quality)? My mono's have valves designed for TV (509s ) and consequently were presumably made/designed to operate for longer periods in very warm (inside TVs) conditions. T. de P. once mentioned that mine should be used for a few hours each time rather than short periods.

 

[davidsrsb]

The advice is correct, turn on at the start of the session and leave on until the end. Turning off at the end of each LP side will thermal shock stress everything
Valved TVs were not reliable, I remember my father swapping valves regularly, especially the line output

 

[TheDecameron]

The valve doesn`t know about distortion, it only knows about dissipation, if the Guitar amp achieves its effect with a flaky power supply and an undersize output transformer it doesn`t follow that the valve is being overdriven.

It probably is though, but then I suspect that normal usage hours of a guitar amp is a lot lower than a hi-fi system used for several hours a day (say).

will i take any difference if I play Smoke on The Water with a bit of reverb?

 

[davidsrsb]

If you see the valve change colour when pushed hard, you are reducing its lifetime

 

[Mike Reed]

Valved TVs were not reliable, I remember my father swapping valves regularly, especially the line output

Don't think any TV we've had, as a family or as a student 14 years later, or since (and I've never been without one) ever had a valve problem. I remember either reading or hearing that T.de P, in the nineties, saying that he chose the EL/PL 509/519 (?) because of their reliability.. I wonder, though, whether my big (27" ?) Sony in around 1975 was valved or not. Certainly CRT, as were its successors; not sure when s/s TVs came in.

 

[Arkless Electronics]

Don't think any TV we've had, as a family or as a student 14 years later, or since (and I've never been without one) ever had a valve problem. I remember either reading or hearing that T.de P, in the nineties, saying that he chose the EL/PL 509/519 (?) because of their reliability.. I wonder, though, whether my big (27" ?) Sony in around 1975 was valved or not. Certainly CRT, as were its successors; not sure when s/s TVs came in.

For quite some time TV's were hybrid. Valves doing most of the high power and high voltage stuff and transistors and IC's the rest. Line output and EHT rectifiers were about the last to go SS. I expect the PL509/519 was chosen for it's cheap availability and high current handling. They were about the last valve to still be mass produced so cheap and easy to get.

 

[Whaleblue]

...but we are talking stupidly high complete headbanger type volumes here, way above what any sensible person would ever play at...

Such as someone trying to recreate pub band volume at home?

 

[Arkless Electronics]

Such as someone trying to recreate pub band volume at home?

Who'd do a silly thing like that?