Replace tubes yearly?


I just watched a Paul McGowan video (PS Audio) about the wisdom of leaving your gear powered on all the time. I get that. He also said that vacuum tube gear is the exception and not to leave it on all the time. I get that too.

But he also mentioned that it didn’t make a huge difference since you probably should replace your tubes every year.

Is that true? I have an Audio Research LS-16 tube preamp from the late 90s or early 2000s. I don’t think the tubes have ever been changed. I’m not really a ’tube’ guy but this unit was given to me 6 or 8 years ago. As far as I know these tubes are original.

At one point I got curious about the different sound quality potential of different tubes and another Audiogon member lent me a set of tubes to try out. I could definitely tell a difference but did not think the new ones sounded better than the original ones. I mention this because at that time the original tubes were quite old and still sounded quite good. And still do.

So, bottom line is, is there any real need to replace tubes on a schedule of some sort. Maybe its different if it is an amp versus a pre-amp?

 

n80

The life of a tube is greatly dependent on the type of tube, the operating conditions of the tube, and even the specific manufacturer of the tube.

Power output tubes tend to have shorter lives than linestage tubes or the input and driver tubes of an amplifier.  Even among output tubes, the ones that are called upon to output high wattage tend to have short lives.  A lot of manufacturers, in order to claim high output, create operating conditions that mean shorter life than if they backed off a bit on those operating conditions that shorten life.  

While the smaller signal input and driver tubes tend to have a longer life, these too vary greatly in how hard a particular amp drives the tube.

Given that there are so many variable involved, there is no simple formula, such as change tubes after this or that time interval.   Both my amp and linestage drive my tubes so gently that I have not had one tube go bad in over 15 years of operation.  Even at the start of my use, the tubes that were put in were used tubes of unknown prior usage.  Most of these tubes were probably well used before I got them.  But, all my tubes are run so gently, they are expected to last a very long time.  This is a VERY good thing because they are all expensive.  My output tubes are 349s, the driver tubes are 348s; my linestage tubes are 310s.  

Short answer: No.

Having a second set of tube around to periodically (anywhere between once a year to every 5 years) check whether you notice something, can be considered. But a yearly schedule is nonsense. If anything, it depends on numbers of hours on the tubes. If that would be important, then tube gear manufacturers would include a cumulative time counter on gear; I've seen those in electron microscopes to keep track of filament age, but am not aware of such features on audio gear.
There are so many variables (type of tube, circuit design, on/off cycles, total time, individual tube variance, ...) that there is no general rule possible.

And then there is the burn-in (allegedly, I have not noticed anything on my tubes). So first it sounds bad because tubes are not burnt in, then change them after a year because they sound bad? LOL! If that is so much of a concern, then rather stick with SS.

Relax, enjoy your music. If you like, do some tube rolling for fun. my 2c.

"But he also mentioned that it didn’t make a huge difference since you probably should replace your tubes every year."

That is a ridiculous statement for him to make!

 

Power tubes like EL34's and KT88's are good for about 2500 hours or more. But may go longer in an amplifier with a conservative design. Small signal tubes with numbers like 12AX7, 12AU7, and 6922, and rectifier tubes like 5AR4 may go 10,000 hours. So you get years and years of enjoyment. Using a tube tester may or may not tell you if you need a replacement. The best approach is to buy a new set of tubes, and install them. If they don't sound a lot better, put in the old ones and suck every bit of life out of them.

@yogatma 

+1

It depends on the tubes. But annual is not an appropriate schedule. Hours on the tubes. This is why tube amps have hour counters. Your component manufacturer should recommend the number of hours. It is dependent on how hard they run them. 

For instance ARC recommends 2,000 on the 6550 tubes and 3,000 on the rest. 

Unless a tube fails in someway, you never have to replace your tubes.  Run them for 30 or even 50 years at a time and they will function.  Now your equipment won't sound it's absolute best as the tubes age, but that's a very subjective observation.

I don't know of any power tubes that will last 30+ years, but for small signal tubes in conservatively designed circuits it shouldn't be that big of a deal.  Again, they won't sound perfect, but I can't do the things I used to do 30 years ago either.