Why aren't new vacuum tubes as good as old ones?

Wolf, I know some of the techs at ARC. They use the KT-120s, but apparently really have to weed through them as many of them arc (no pun intended) prematurely.

However its a pretty neat tube- lotta power handling.

One way to look at it is they (Russia and China) don't take as much care, but there will still be tubes that hold up. We've seen some of our Russian power tubes (6AS7G) go for well over 20,000 hours. But that is by no means the norm...

I think they are taking greater care with the premium tubes we are seeing- like the Psvane, TJ Music and Sophia. Our customers have been giving use good feedback on those (which at this point has mostly been the 6SN7- which is our main signal-processing tube).

I had a sloppily made Psvane pair that I sent back, but that was cosmetic really (on one tube) and it was a matched pair...they did seem to sound OK. The next pair was better, and have remained in their sockets. I wonder what the number of bad 120s is relative to others at ARC, as there hasn't been much reporting of 120 failures otherwise, or at least from what I found in my research (research...ha...more like "lazily poking around").

Is it fact, or hype?

It's fype.

What is the definition of "good"? Sonic quality? Durability? Given the longevitiy of some tubes (300b comes to mind) and unless a tube fails "early," it will be hard to prove that new tubes are predictably shorter-lived compared to older ones. Or am I wrong?