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In Reply to: RE: Tubes tested & burned in for 48 hours at audio research posted by mondial on February 13, 2017 at 16:39:37
Will these parameters improve the performance and reliability of these tubes?
No.
At best, they can indicate the performance, or reliability....not improve it.
"I can't compete with the dead" (Buck W. 2010)
"$45 gets them out the door tomorrow. $50 gets them out the door yesterday" (Byrd 2016)
Follow Ups:
I don't totally agree. It will definitely catch some cases of "infant mortality" that otherwise would occur after the tube was sent to the customer. That is a positive step in improved reliability (and minimizing customer hassle)!And I will also say that it's not only the number of hours burned in, but the number of thermal cycles the tube experiences. We all know how tubes often fail during the first moments after the tube is turned on. That's why in my process there are multiple on-cool down-off cycles.
So it is a dilemma - you can burn up a significant amount of a tube's life with extensive burn in, yes. But you will also catch some tubes with issues before they are put into someone's gear!
Edits: 02/14/17 02/14/17
Again, Improve is the key word. Burning in will not improve any aspect of the tube. It may reveal less than optimal performance, or other operational concerns, but there's no improvements to be realized.
"I can't compete with the dead" (Buck W. 2010)
"$45 gets them out the door tomorrow. $50 gets them out the door yesterday" (Byrd 2016)
If eliminating some infant mortality isn't an improvement in the tube reliability then what is it?
You can't improve a tube's reliability by removing lesser tubes around it.
Improvement in reliability comes from improvements in manufacturing.
"I can't compete with the dead" (Buck W. 2010)
"$45 gets them out the door tomorrow. $50 gets them out the door yesterday" (Byrd 2016)
You're grasping at straws IMHO. While any individual tube can't be changed once it's made, the overall quality of any production run of tubes is raised by eliminating tubes with issues.Why do you think automotive quality ratings are measured by the number of problems per 100 vehicles?
Quality is judged by evaluation/analysis of a reasonably sized sample of the product being evaluated. By weeding out problematic items from the sample the overall quality level goes up. And any individual consumer is more likely to have a satisfactory experience with the product as a result.
Finally, think of it this way. If a customer buys a quad of tubes from me and one fails, is it accurate to say that tubes I sell fail at a 25% rate? Well, if you limit it to tubes sold to him - yes. But not when the sample is larger because only a few purchasers have a 25% failure rate. Most have a 0% rate! Which means that the more infant mortality prone tubes I weed out the better the odds of any given purchaser having a 0% failure rate - THE BETTER THE OVERALL QUALITY for any given purchaser. That's why proper testing and all that go with it - including burn-in/run-in - is one path to improved quality.
That's all I have to say on this.
Edits: 02/16/17
Say all you want, or not, it makes no difference to me. Different views. Different news.
"I can't compete with the dead" (Buck W. 2010)
"$45 gets them out the door tomorrow. $50 gets them out the door yesterday" (Byrd 2016)
Well, it is interesting and of some importance to me what you say since reasoned debate often can clarify an issue - or at least encourage further thought.
I'm genuinely sorry that you find it uninvolving.
Now I GOTTA run!
...I've run into a lot of Russian power tubes whose bias was unstable if used out-of-the-box. 24hr burn in at low current stabilized bias for about 90% of them.
Tweaking the bias every 10 minutes during the first 12-24 hours of run-in is part of the fun of owning tube amps.
And then, as a bonus, you might get lucky and find that one of your 'platinum matched' tubes refuses to hold bias even after 48 hours of use and you have to decide on sending back all 4-8 matched tube for replacement or just the one that won't hold bias which. of course, means your 'platinum matched' set is now of a lesser grade of valuable metal.
Like maybe 'brass matched'?
the quality of the tubes the customer receives from the dealer.
That might be the most important 'aspect' of tube quality as it relates to this discussion.
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