Lifespan of a quality solid state amplifier?

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I'm dumbfounded you would continue to defend what is clearly just plain wrong. You are evidently just making stuff up as you go along this time.

That is absolutely not the correct use of the term. It means something has half it's life left, not that half of a group are dead. Find one other example where it is used as you used it.

How could you possibly have seen it many times? Give me one example where you have seen a group of caps where 1/2 have failed after 20 years.

You'll have to do better than they teach it in technical school to have any credence. I taught in a technical school for ten years and I've never heard that 1/2 after 20 years statistic before. If it is correct you should be able to easily produce at least one credible source, but of course you can't because there are too many variables to have a statement like that be true.

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Plutonium is a good idea though, it has a half life of 80 million years ;>)

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In 1981; I bought a Hafler DH500(kit), to power the woofers of my biamped system(I was a Hafler dealer, at the time). Gave it to my son, 15 years ago, when I bought a Hafler Trans*nova 9505, to replace it(same purpose). He recently sold it to another friend of ours, and it still functions perfectly. Until now; it NEVER had an easy life!

Many new electrolytic caps are + or - 10-20% and they are usually further out of spec after 10-15 years. They may still work, but they are cheap, why not just replace them. I like Spragues or F&T. If they will fit, I use v-Caps in coupling or input cap locations. They are soincally just superb. I have had a few Illinois electrolyics leak, the brown goo, and replaced those. But, they were 15 years old or more. Jallen

> Filter capacitors have a half life of about 20 years.
> What that means is that in a 20 year period, about
> half of the caps will have failed. This is true of
> transistor and tube amps.

Ralph, I would call this MTBF, or mean time between failures.

http://en.wikipedia.org/wiki/Annualized_failure_rate

"A vendor-quoted MTBF implies that half the drives in a large population will fail within that time of operation."

If in technical school they used half life, I would suggest they either got the term wrong or the definition has now evolved into its current usage as "the period of time it takes for the amount of a substance undergoing decay to decrease by half."

the twenty year half life thing is just wrong and does not apply. No amount of posting will make it right. Half life refers to radioactive material. And it is not mean time between failure. MTBF most often is measured in hours.