Two things. ARC wants to maximize the listening pleasure of it's owners, without much regard to the cost of tubes.
So they want to be certain the tubes in use are always going to be excellent, and never 'wearing out'.
Thus thier recommended replacement intervals.
No problem in my mind with thier philosophy.
Another thing is the preamp tube, and the power tube are really two very different animals as far as tube life.
Power tubes are run hard, and wear out pretty fast, and when they fail, it can be fireworks. So you want to replace power tubes when recommended.
Preamp tubes (depending on the usage and design) can last a very long time. And never do any explosive things. (well possibly, but i never heard of it) A few designs do run preamp tubes hard, some notorious preamp designs went through 6DJ8 tubes fast! So preamp tubes (and preamp type tubes in an amp) can be used until they start getting bad/noisy.
You do NOT want to leave a power tube running without a person present. the exploding/fire etc possible distructive death of a power tube is real. And so its the fire hazard.
Not so for a preamp tube.
I leave my VAC Standard preamp on 24/7 with a pair of 12ax7 and a pair of 12au7 in there, and a sealed case, (separate SS power supply) with little generated heat, I expect them to last pretty long even on 24/7 (as i listen over ten hours a day average anyway)
And finally playing music or idling. Preamps are mostly class A 100% so the tube is run at 100% at idle, and actually less when playing music.
Power tubes can be anywhere in the class "A" to class "AB' spctrum, and depends on how they are biased etc.
Cd player tubes are in there as a preamp tube or tube buffer. and are not stressed much. They should last a long time also. ditto most headphone tubes.
A few BIG headphone amplifiers use real amp tubes though.
So they want to be certain the tubes in use are always going to be excellent, and never 'wearing out'.
Thus thier recommended replacement intervals.
No problem in my mind with thier philosophy.
Another thing is the preamp tube, and the power tube are really two very different animals as far as tube life.
Power tubes are run hard, and wear out pretty fast, and when they fail, it can be fireworks. So you want to replace power tubes when recommended.
Preamp tubes (depending on the usage and design) can last a very long time. And never do any explosive things. (well possibly, but i never heard of it) A few designs do run preamp tubes hard, some notorious preamp designs went through 6DJ8 tubes fast! So preamp tubes (and preamp type tubes in an amp) can be used until they start getting bad/noisy.
You do NOT want to leave a power tube running without a person present. the exploding/fire etc possible distructive death of a power tube is real. And so its the fire hazard.
Not so for a preamp tube.
I leave my VAC Standard preamp on 24/7 with a pair of 12ax7 and a pair of 12au7 in there, and a sealed case, (separate SS power supply) with little generated heat, I expect them to last pretty long even on 24/7 (as i listen over ten hours a day average anyway)
And finally playing music or idling. Preamps are mostly class A 100% so the tube is run at 100% at idle, and actually less when playing music.
Power tubes can be anywhere in the class "A" to class "AB' spctrum, and depends on how they are biased etc.
Cd player tubes are in there as a preamp tube or tube buffer. and are not stressed much. They should last a long time also. ditto most headphone tubes.
A few BIG headphone amplifiers use real amp tubes though.
