Was expecting this would happen sooner or later, i have a class A amp I built with a brand new NOS pair of Philips ECL82 tubes.
My friend who crashed the night at my place must have been using it for a bit before bed and forgot to switch it off.
Being class A, alot of current would go through the tubes at idle, so im assuming this is not good for them?
Would have only been running for about 8 hours, but still, its not ideal.
Would this have simply reduced the tubes life by 8 hours, or is it more damaging?
My friend who crashed the night at my place must have been using it for a bit before bed and forgot to switch it off.
Being class A, alot of current would go through the tubes at idle, so im assuming this is not good for them?
Would have only been running for about 8 hours, but still, its not ideal.
Would this have simply reduced the tubes life by 8 hours, or is it more damaging?
That's like listening to 8 albums, what's the big deal? Tubes last a LONG time unless you've biased that thing into stupid territory. I'm enjoying music from a Dyna SCA-35 with tubes that are 50 years old and still measure fine.
If you are worried about your gear, how can you relax and enjoy the music?
If you are worried about your gear, how can you relax and enjoy the music?
No harm. Things might have gotten a little warm... especially in this summer heat! I have a self-build with a Hammond power transformer (used well within its limits) that gets too hot too touch after 2 or 3 hours usage, but "too hot to touch" is only about 65ºC which is well within tolerance.
So in summary - the only damage is to your nerves. Enjoy the music
Amusing thread, thanks for starting it
The best part is underlying the fact it is a class A amp, as if it means anything special for a valve amp. Compared to some parallel class AB amps this ECL82 amp is like a pocket stereo. Lotsa ancient radios ran this in "pure class A" without ever considering the the marketing advantages or the damage to valves and the environment
The best part is underlying the fact it is a class A amp, as if it means anything special for a valve amp. Compared to some parallel class AB amps this ECL82 amp is like a pocket stereo. Lotsa ancient radios ran this in "pure class A" without ever considering the the marketing advantages or the damage to valves and the environment
As stated all the old AA5 and similar tube type table radios were class A, and most ran the 50C5 or 50L6 right at the edge of spec (which was conservative for this reason). Many of those radios ran daily until they were replaced with solid state, and often had their original tubes when discarded. I ripped those radios apart as a kid for guitar amp parts, and if any tube was weak, it was the rectifier, not the output tube.
I built an SSE amp (SE KT88) over 10 years ago It served as the amp for my computer speakers for about 3 years. It was on almost anytime I was home. It still has the original tubes in it.
If you had good quality tubes, and the amp didn't overheat due to poor convection or radiation, them no harm was done.
I built an SSE amp (SE KT88) over 10 years ago It served as the amp for my computer speakers for about 3 years. It was on almost anytime I was home. It still has the original tubes in it.
If you had good quality tubes, and the amp didn't overheat due to poor convection or radiation, them no harm was done.
But, correct me if I am wrong, if the max. plate dissipation
(which is obtained at idle current with no AC power to deliver to the load)
is safely below the allowed maximum value (both triode and pentode of course),
then there is nothing to worry about.
Assuming of course that there is a "normal" ambient temperature.
(which is obtained at idle current with no AC power to deliver to the load)
is safely below the allowed maximum value (both triode and pentode of course),
then there is nothing to worry about.
Assuming of course that there is a "normal" ambient temperature.
There are two states which lead to long and happy lives for valves:
1. Everything switched off. No heater current, cold cathode, no anode current.
2. Everything switched on. Normal heater current, hot cathode, normal anode current, proper bias - all within the datasheet spec. Each hour of use takes an hour from the life of the valve, but you never know what that is anyway.
Valves age badly and get damaged when people try to do something else with them, such as hot heater but no anode current or warmish heater and some anode current. Some attempts at helping valves last longer actually shortens their life, such as some 'standby' switches.
1. Everything switched off. No heater current, cold cathode, no anode current.
2. Everything switched on. Normal heater current, hot cathode, normal anode current, proper bias - all within the datasheet spec. Each hour of use takes an hour from the life of the valve, but you never know what that is anyway.
Valves age badly and get damaged when people try to do something else with them, such as hot heater but no anode current or warmish heater and some anode current. Some attempts at helping valves last longer actually shortens their life, such as some 'standby' switches.
Last summer, I left my SET amp with 6BG6G tubes on for four days. House didn't burn down, the electric bill wasn't noticeably higher and the power transformer was warm, not hot. No other ill effects were noted and the amp is playing right now with the same tubes. Still sounds good. Relax, have a home-brew.
When I started in broadcasting, tubes were still used. We mostly kept that stuff on 24/7.
The worst case may have been the transmitters. They used a TV sweep tube nominally run very close to rating. If you didn't tune the load on the nose, the tube would die in hours-- I did check the tune monthly. These lived in a filing cabinet in a boiler room, poor environment. I do not recall any tube failures in 12 log-years.
We also had a Fisher 500 so we could rebroadcast a partner station when our studios were idle. I do not recall any trouble with that hot beast, other than occasional fine-tuning to keep it on center.
The worst case may have been the transmitters. They used a TV sweep tube nominally run very close to rating. If you didn't tune the load on the nose, the tube would die in hours-- I did check the tune monthly. These lived in a filing cabinet in a boiler room, poor environment. I do not recall any tube failures in 12 log-years.
We also had a Fisher 500 so we could rebroadcast a partner station when our studios were idle. I do not recall any trouble with that hot beast, other than occasional fine-tuning to keep it on center.
No need to worry if the amp is built right. 8 hours of straight running is the best-case for a tube. A lot goes on inside a tube on cold start, especially with a solid state instant-on power supply, and none of it is good for it.
My daily driver at work is a 7-tube series string AM-FM set and I've put probably 2K hours a year on it for about a decade without problems. It's still plenty loud and if anything one of the IF tubes is in need of replacement but it might just need an alignment.
My daily driver at work is a 7-tube series string AM-FM set and I've put probably 2K hours a year on it for about a decade without problems. It's still plenty loud and if anything one of the IF tubes is in need of replacement but it might just need an alignment.
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