"05-11-11: Swampwalker One comment on ARCs recommended replacement intervals. My cynical side says that it's likely that there is also an element of profit maximization as well as client satisfaction."
Agreed. When I read Elizabeth's post I thought it should have read "Three things", this being the 3rd. File this revenue stream under 'consumables.'
One comment on ARCs recommended replacement intervals. My cynical side says that it's likely that there is also an element of profit maximization as well as client satisfaction. ARC-sourced tubes sell at a premium and I imagine that they also do a pretty good business re-biasing some of their power amps. If you run a search, you will find that the tube replacement/re-biasing process on some of their amps is pretty complex and not for the faint of heart. Just sayin'; not trying to pick a fight.
6bq5 -- I can't speak to other tube makes or gear, but in the case of ARC, the factory recommends that power tubes in more current models, such as 6550Cs, be replaced every 2000 hours. These particluar tubes bias at 65 mV. ARC has replaced the 6550C in some amps with a new tube, the KT-120, which is supposed to be more robust. Time will tell if service life will be extended. However, in the case of pre's and other input gear, such as phono pre's and CDPs, the more recent models use 6922s and 6H30s. ARC advises that these audio/signal tubes be replaced at 4-5,000 hrs. Certainly in the case of ARC gear, I am not aware of any tube, at least in current models, that has a 10,000 service life. Perhaps, longer tube life might be found in gear from other companies.
I think the question at hand is whether there are suggestions or recommendations out there in audio-land that can help extend, or at least not shorten, tube life -- whatever the factory's recommendations might be. I think you put at least 2 recomendations out there in your post. Thank you. Your advice makes a lot of sense.
Most commercial and military tubes were designed with a 10,000 hour operating life. This life expectancy can be shortened by primarily two activities: 1- frequent power cycling, On/Off [if you are planning a day of listening and want a few hour break, go take your break, but leave the equipment on]; 2: High Bias/hard use- if the B+, or Bias is at or above the design threshold, then the tube(s) will be driven 'harder' which will cause the plate to off-gas, which in turn will eat up the getter, and in short shorten the tube life. There was an amp in the late '80's/early '90s that used 8417 power tubes at Very high B+, and the tubes would only last about 3,000 hours. I have both AI pre-amp (M3) and MR power amp (RM-9MK-1) and have re-tubed each once - after ~10 years of use. The getters were pretty transparent - more like ghosts, and the 9-pins were getting noisy. They (the tubes) are designed to be replaced, and a prudent owner of tube equipment will have spares... Happy listening
What about taking steps to cool the tubes down while they are in full operating mode? Such as running a small, quiet fan toward the tubes. Say one of those super silent computer fans, or A.T.M.fans (Active Thermal Management)? Could providing a cool breeze or flow of air directed toward the tubes be a solution? Extend tube life? Or would that not matter? As we all know-Heat is not our friend. Most tube amps and alot of tube Pre's generate significant amounts of heat which can't be a good thing, right? If one could lower the ambient temperature in and around the proximity of the vacuume tubes, wouldn't it stand to reason that life span and efficiency would increase? What good is all that generated heat doing anyway? Please advise.
No matter what you do, tubes will eventually wear out and that is a fact of life. The most important thing is just be reasonable and enjoy the music. If you plan on listening to music on any given day, leave it on for that day. I believe too that cycling tube gear on and off several times during a day can be more harmful than good in regards to tube life. A case in point is that Audible Illusions believes this is true and design their tube preamps where the tubes are always lit even when the preamp is powered off. But now I'm just talking tube preamps only.
Ckoffend, your comment is consistent with my thoughts too. However, I am not an electronics techie, so I have no real basis for formulating a view, ergo why I asked the question.
There are a number of A'gon members who are heavily involved in tube based electronics. To be courteous, I will not mention names or their A'gon handles, but perhaps if they catch this thread, they will chime in with some recommendations and guidelines that are based on their considerable knowledge and experience.
I dug into the records and found that Alfred Kayser of KR Tube Products sold me my nos Mullards and advised me to not run the amp more than 4 hours at a time. That was over 3 years ago. Absolutely no issues with the tubes in that time. Also, the tubes I bought have almost doubled in price since then...
I believe turning the tubed device off for a short listening break (such as the few hours referenced) will not contribute to the overall life of the tubes. I think/believe it is better for the integrity (physically) of the tubes to remain at a relatively steady state and temperature versus cooling off and heating back up.
Additionally, with a lot of tube equipment that does not incorporate a soft-start type of approach for the tubes, it is my belief and understandinging that the turn on process is more wearing and a greater risk to the tubes than leaving them on for a mere few hours.
In such a case it would be my advice to leave the equipment running for a good portion of the day versus turning it off and back on. But please note that I am not a tube expert but have over the years owned some very good NOS tubes that I paid a fair amount of money for.
"i run my tube amps 4 hours max. if i want to keep going, i turn them off for 30 minutes then back on.
The seller of my premium tubes gave me very similar advise. I wish that Id pressed for an explanation at the time, but I was suffering from sticker shock. Does anyone know?
Another question: Any suggestions or guidelines on turning tube gear off when taking a listening break, and then back on again when the listening session resumes, if the break only lasts a couple of hours? The point of the question is predicated on the notion, perhaps wrong, that the process of turning tube gear off and an again -- by itself -- stresses and preliminarily ages tubes. Does the suggestion or recommendation change in the case of amplifier power tubes versus signal/audio tubes?? Thanks
As above tubes will burn out if left on. There are similar threads in the archives. Also please avail yourself to Audio Asylum Tube Asylum. A very knowledgable group of enthusiasts have addressed this issue. That said I had a Jolida CD player with tube output. I rolled the Jolida tubes (Shuguang?) to NOS Mil Spec Mullards. The change was immense and worth the cost of the tubes. When the CD player gave up the ghost I retrieved the Mullards and tested them after a number of years in service. I didn't leave it on but played it often. I tested the tubes and much to surprise they very strong. So for whatever reason I have seen equipment that was not hard on the tubes. Could it be the design? Possibly I really don't know. I hope this doesn't confuse you. All my other (a lot) tube gear I turned off or used up tubes listening.
Dgaylin-there are NO stupid questions, except for the ones you don't ask. I don't have a clue either when it comes to tube life. So what is the answer? Hopefully we can get some tube aficianados to chime in on this. I have been a "solid-state" guy for close to 40 years, but decided to try a tube preamp with my S.S. monoblocks. It has been a "MAGICAL" experience and brings a whole new leval of wonderfullness and "ease" to the sound. But Russian-made 6h30 "super tubes" don't come cheap. At $300.00 a piece (x8 for my preamp) I watch my time on them, and don't leave my preamp on once I am done listening. I DO however leave it in "stand by" mode. And I know that burns up tube life, even if at a slower rate. B.A.T. says that's not a problem, and that 6h30's should last 10,000 hours. But what about other tubes? What about the the scenerios you bring up? Tube c.d. players? DAC's? Amp's? Running "idle" versus running with a signal flowing through them? All very valid questions. Will you "tube" guys please impart some of your experiences and knowledge with us tube newbees?
I've heard turning tube equipment on shortens the life of tubes but I hadn't heard anything about a four hour run time. In my amps and preamp the 9 pin tubes are always on to some degree (heater mode) and they and the power tubes in the amps are powered up and down by variacs to reduce shock to the tubes and extend their life.
Your tubes are very expensive I understand your position and was only wondering what the thinking was behind that specific amount of time.
Dgaylin, I would leave it on all day if you plan on listening again within three to four hours for the best possible sonics. If you turn it off before retiring to bed is the best route to go.
Thanks all. Yeah for sure, no point in leaving tube gear powered on when you are not using it, esp. will NOS expensive tubes. But my issue is that I often turn on my tubed CD player, and listen for a couple of hours and know that I'm going to be listening again in 3 or 4 hours, and the question is, should I turn it off, or not?
Of course to be safe, I could just turn it off. But I'm curious if there is really just minimal wear on the tubes when the CD player is on but not playing.
Samhar, i have very nice (and expensive) nos Mullards and want to maximize their life. I was told by the canadian dealer whose name escapes me to do just that. he seemed to know what he was talking about and i am happy not to take any risks with this lovely stuff. :)
Tubes are slowly wearing themselves out as soon as their powered up. The circuit design has a big influence on tube longevity and NOS tubes aren't getting any cheaper. No sense in taking a chance on leaving tube gear powered up other than an hour prior to a listening session & then should be turned off when your done.
When powered up, I would think that when tubes are driven by an audio signal as opposed to no signal at all would in fact reduce their life span, especially in tube amps. I have had very old tube gear that still works with their original tubes. Maybe low usage could of contributed to this or again it goes back to how the tube circuit is designed or maybe both.
Good question I think. I would guess that for my Class A running amp it does not matter because they're full on at all times. But PP class A/B?My guess is that the bigger the input signal the more work they're doing and the faster they wear out.
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