i appreciate all the comments. I think I power on and off 3 or 4 times a day. Today will be 5. I sent an email to VAC to see their thoughts on it. Replacing 8 300Bs is a pricey move that I’d like to put off.
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https://www.youtube.com/watch?v=P7WkFEVbxu8 https://forum.audiogon.com/discussions/tube-failure-what-would-happen-in-worst-case go ahead, leave em on, walk away, don’t worry be happy |
tempted to turn on and leave on all day. Instead of powering up and down many times. Correct answer depends entirely on what you mean by "many times". If you mean many times a day, the greatest most intense stress is the thermal expansion going from off to on. This is why some designers like Herron incorporate slow warmup circuits. Greatly extends tube life. But if "many times" means one time a day? Well then look at it this way. Let's pick some arbitrary numbers and say tube life just sitting idle is 5000 hours. At idle. Playing music uses more power, tubes get hotter, wear faster. Let's say you crank that thing full blast all the time. Tubes last 3000 hours. Just throwing numbers out to get you thinking in terms life and wear. Though these are probably in the ballpark. Okay so now every time you turn them on from cold, that flip of the switch is something like at least an hour of running idle. So if you are turning it on and off 3 or 4 times a day then probably better off just leave it on. And that's how that works. |
Some equipment has built in protection. My Cayin tube Amp has a 30 second delay, test and I suppose you could call it a soft start. My prior McIntosh SS amp has a test/delay protection sequence. My Adcom ACE-515 power enhancer (not a power conditioner) power controller (in my office) has a time sequenced 10 sec turn on delay for the amp; 30 sec turn off delay for accessories. (prevents thump to speakers). |
@Vineland, Wise decision. Some people can make an argument for leaving the small low signal tubes on continuously (Although I don’t). I can’t imagine any reasonable case for keeping the power output tubes on 24/7, none. Now if your amplifier has a very low draw ’stand by’ mode that’s a possible exception. Good quality 300b tubes have long lives (The EML XLS and vintage Western Electric 300bs have reported 40,000 hour lifespan) but I wouldn’t gratuitously waste useful tube lifespan leaving them on constantly. If I’m home all day I leave my 300b amplifiers (Mono blocks) on through out the day if listening sessions are planned and then shut them down at the end of the day . I do this rather than turning on and off multiple times during the day. Charles |
If a manufacturer ever recommended leaving tube gear on all the time in order to prevent damage from the act of turning on the gear, I would never buy from that manufacturer. It is not hard for the manufacturer to put in a soft start circuit to prevent damage from turn on. A tube is not like an incandescent light bulb (which is designed to come on instantaneously) and it warms up relatively slowly so that it does not suffer as much from thermal shock of being turned on. There is a potential for damage if the plate voltage ramps up too fast such that full voltage is applied before the cathode has warmed up enough to be fully emitting electrons (referred to as cathode stripping). Cathode stripping is less of a concern if the amp is tube rectified because the rectifier itself slowly ramps up the plate voltage as it warms up. Some amps, particularly those with solid state rectification will have a circuit that limits plate voltage until the cathode has time to warm up (my linestage, although tube rectified, has such protection). The only good reason to not turn off tube gear when one is not listening to it has to do with warm up time. Tube gear, like all other gear, sounds best when it has been on for a while. The good news is that tube gear usually sounds good within five to ten minutes of being turned on, which is a much shorter warmup period than solid state gear requires. I leave my gear on when I am taking a short timeout from listening, but, otherwise I turn it off, particularly when the gear will be unattended. |
I have NEVER heard a manufacture tell anyone to leave the "Power Valves" on.. EVER.. Then again, what do I know.. The little signal valves, I've seen stay on for months at a time.. Some designs are VERY low voltage and the valves last 15-20,000 hours.. I've not seen power valves do that.. 5,000 hours is really a push. 2-3000 is more like it.. I've never seen a signal valve erupt, and breach the glass, rectifier and power valves, I have... What about some of the hand made valves.. 4K+ for a pair. Rebuildable. Maybe I should start making them out of old pint and quart canning jars.. Gears are grinding... Regards |
This is a frequent debate that is never settled. One side believes leaving tubes on is a fire hazard and uses up the tube faster and the heat also wears out the rest of the amp sooner. The other side believes that turning your tube amp on and off is the most destructive thing you can do to it. Of course there are others with opinions all over the spectrum between these opposing poles. My advice is to call up the manufacturer of your amp (even if you didn’t buy it new) and do whatever he advises. |
My 300B SET amp has a standby function that allows me to warm the tubes up gradually. I think when they are in standby, at what is essentially a very low idle, it's not using up any or very much life of the tube. This is why, if I have another custom power amp made in the future I plan to request a standby switch. |
No it's not a good idea. You need to be there or at least in listening range.. It's just the nature of the beast. Those are exposed bulbs, Valves, or tubes.. Be wise. They don't always fail and keep it in the glass, get my meaning.. I've seen an valve fire or two. LOL TRUST ME the first one is an eye opener.. I was 15.. I learned QUICK.. Almost burned down my mothers house. I had to pay for the carpet I destroyed.. That wasn't funny. Mac MC20s and a MAC 30 Kit.. BLEW a 6L6.. caught the carpet on fire.. I was trying to power a Jensen Imperial Sub.. It worked great.. UNTIL... My mother was a saint... regards |
There is so much debate about this because powering on is probably the hardest thing you can do to tubes. Personally I always turn mine off when I am finished listening for the day but leave on as long as it is possible I WILL listen. So approx 4-8 hrs on days when I listen to music on my system (not every day). I would think that if you spend significantly less time listening than not listening turning off is a good way to go. My amp is also class a so it is always full power all the time. So that is a factor for me. |
