Bottlehead Forum
General Category => General Discussion => Topic started by: WK3K on June 16, 2020, 08:08:11 PM
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What is the expected life on a set of tubes in most of the applications in the Bottlehead universe? Assuming you run an amp for 10-20 hours a week, are we talking years? Decades? Just curious about how often I might expect to replace tubes and if there’s a sonic advantage to switching to a newer set after x number of hours. I guess maybe a tube tester might be the next project...
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Which tube, in which amp? A lot depends on the tube, and how its used. We are talking thousands, if not tens of thousands of hours.
I worked out my preamp with 4P1L tubes has clocked up over 50,000 hours, still sound great to me, and the bias points had hardly drifted at all last time i checked. But every tube and application is different.
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Like Mark says, it depends on the tube, how it’s biased, etc. Most of the better 12AT7s have 10,000 hour heater ratings, but I have heard that they can last a lot longer than that.
Jamie
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I have a reasonably high number of datapoints, since I service many of our legacy products that are somewhat ancient. Typically you should expect 2A3s and 300Bs to last 5-10 years, with some slow degradation in performance as you near the end of life. For preamp and driver tubes, especially when they are old stock parts, it can be a challenge to actually wear them out.
PJ uses the first SEX 2.0 prototype amp on his TV, and he is still on the first set of tubes. I have an amp that's very similar to the SEX amp running 24/7/365 in my workshop, and it will eat through tubes about every 5 years (that's about 40,000 hours).
There are absolutely certain tube preamps that I won't name here which run their tubes well over the plate dissipation rating and sometimes also the plate voltage rating at the same time, and you can expect very short life in those products. Also big KT88/6550 amps seem to wear out the power tubes pretty quickly.
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Thanks y'all. I guess I can stop beating myself up when I forget to turn an amp off and leave it on overnight.