He did say " ...how do you know..."
I've not sweated in a good long while.
Never due to tube breakages or burnouts. Only from one of two things have I toiled over tube replacements. My own desires for them, or those tubes which came with the device were overstated as to their wherewithal.
Primarily it's from my desire to have fresh, or try some other flavor.... but I think that's about the same thing... isn't it? Somebody's buying some tubes for some reason.
As for the Ferrari notion.... yeah one would think so. I did.
OK buy another set of tubes right off with your new "I'm keeping this for ever item"
Then, suprisingly, forever comes along a lot sooner than you had thought it would and for whatever reason a new toy seems a better move to acquire.... and it doesn't use the same tubes.
I've got a fair number of matched pairs of Amperex and Telefunken 6DJ8 CLASS tubes presently with nothing but a box to put them in. PQ US 7308 WHITES, 7308 greens, orange, Tele cc88, ecc88, JAN Phillips 6922, and some others I don't even remember.... RCA & Amperex 12AT & 12AX, Teles as well, Tungsol minis, Ge minis, RCA minis, and none have more than 100 hours.... and no one will buy them.
I offered them all at well below the going rates a year ago with no activity whatsoever.... cause they were used I suppose and I had nothing other than my own feedback to account for them
. No recently tested figures maybe was it. Beats me, but all those tubes are proported to have upwards of 10K hours of life. So whats 100 or so if priced very attractively?
Its cause their used now. IMO
Or maybe it was the timeing.... it sure wasn't due to their pricing.
It's a nice idea to have auxilliary fresh tubes about, but then there are indeed pitfalls.... for as soon as you plug 'em in and try 'em, you can no longer sell them as NOS... and that can hurt.
What too if your gizmo has four, six or eight tubes instead of one or two>? Or several types in its topology?
A tester for those who can use them seems the best idea. Then theres calibrating that too.
I went one other way to figure out if tubes were going on me or if a tube run device was causing an issue. Buy new cheap same types, or another SS likewise component, chealy.
You can merely swap a two tube devices tube about as well. Putting the left onto the right side and so forth.
When the Ferrari is gone however, What ya gonna do with the spare parts left behind?
I can dig you all here about having on hand another NOS set, but new costs way less and does the same deal.
Managing the entry fee alone is tuff enough at times. Anteing up for all the tangential expenses of operation up front is off putting, regardless the wisdom of it at the point of sale.
In any case... I'll continue to sweat and shiver when that time comes.... and it will I'm sure. ;-))