... And he still won't say what the amp is!
Power Amp
My power amp keeps burning up the power tubes. I get maybe 4 months out of them . I have use three different type of tubes that are recommended for the amp. Can anyone help, why this is happening, are all of the power tubes bad?
40 responses Add your response
Although not mentioned, is your amp covered with a cage? I had an amp where the optional cover had poor side venting. The tubes did not last even when biased conservatively. I tossed the cover and the tubes (EL-34s and formerly KT-88s) are lasting years. In other words, do not discount adequate ventilation. Also, it you look at the tubes with the lights out, do the anodes (plates) glow orange at all? If yes, a clear sign of overbiasing. |
What a silly post. +1,000 Well pardon me all over the place. Pardon me a thousand times. Just a humorous response to the post about a "hunch" above. Silly? Hilarious. No more silly than all the squawking and quacking about what brand amp it is. That is irrelevant. The tubes are being blown due to them being operated at higher voltage than their operating parameters require. That situation has absolutely NO relation to who made the amp. Volts don't care whose factory the device came from. The OP had said the amp has auto biasing which is what I predicted the source of the problem was before he posted whether it was auto bias or user adjustable bias. If you notice, the retired mechanic did not ask "what make of car is it?" before being able to give an educated diagnosis of the problem. The same concept of irrelevance is evident in both cases. You're welcome. |
Here is solid advise , Buy a Ayon integrated amp why it it microprocessor controlled you bias it by holding in the button on back and each tube is run optimum ,and saves the tube life , when a tube does go ,it will shut off and let you know exactly which tube it is you wait 20 minutes , the amp rebias allthe tubes and ready to go , you shut off when not using very dependable . |
Hello, I hate that I have to ask. Do you leave your amp on all the time? That recommendation is for Solid State only. Tube amps are turned at about 15 minutes to 30 minutes before use or pushing the amp. Basically warm up time. Please do not leave your amp on all the time. If it is not that then send back to manufacturer. |
Air filter, one of the worst offenders. In a diesel/gas engine it will ruin a turbo and cause it to go through oil like a crazy too. Air filter.. yup...Under 100.00 usd on a HD diesel, 20-45.00 usd for a gas rig.. Second bad fuel filters (low fuel pressure)... Can cause the newer injectors to take a dump... they will leak (drip) or over fuel, and cause cylinder wash, again hi oil consumption, and a lot of premature ware, no lubrication... Regards |
jjss491,129 posts10-21-2020 1:06pmwhy do people come here asking for help -- while themselves not providing remotely enough info so that other people here with knowledge can give a useful answer??? <<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>> The useful answer is another question. Who makes the amp? Just saying. Bad enough the thing is gobbling valves. AY? Really need to hone those mind reading skills. Me I'm a retired mechanic... Top of my game when it comes to that, stuff, reading minds... :-) Regards |
FIRST. Who makes the amp? Go from there. Certainly a problem. Power valves look a little brighter than usual? You only get so many "turn on", with a valve. The way it’s heated up has a lot to do with tube life too. The slower they come up the longer they last. Roberjerman said, they have to be bias correctly. They aren’t.. They are bias to hot for sure (over 50 EL34s 4 months is a push) Dynaco ST 70 come to mind, if the bias circuit hasn’t been upgraded, they will gobble up power valves...Fixed a few of those..25-30 years ago.. Mc 275, can have a small valve that will cause red plating also.. Ideas, ay.. Regards |
Tube life is unpredictable enough that its understandable to be told 4 months is the tubes. But only if its a time or two. In normal use, couple hours a day, tubes should last a few years. More use, higher volume, less tube life. To get it down to 4 months though would be running high levels pretty much all day. Guess you could do this if you have inefficient speakers and listen a lot. Not saying that's what it is, just filling you in on what to expect from a guy with a couple decades experience with tube amps. More likely its like the others said, they're biased too hot, and the service will fix it. You really should name the amp and age and details. Its never derogatory to say what actually happened with a component. It helps us all know what to expect. If its a quality product people will know and say wow that's unusual. If its not people will probably know that too and say yeah as expected and more people will know to avoid. In other words its helpful to know. Not to mention if the place you sent it knows there's like a hundred eyes on this you are more likely to get good service. So there really is no reason not to say, and every reason to fill us all in. |
