Tube life is perhaps the number 1 thing that keeps music lovers away from buying a tube preamp or a tube power amp. But it really doesn’t need to be a factor — read on to see why.
This answer will focus on preamp tubes only.
Short answer: If you have a Backert Labs preamp and you use the stock tubes that we provide, you will probably never need to replace them.
In other brands, tubes can last something like 2 to 8 years, but this is only an estimate and tube life can be shorter, or longer.
Full answer: Preamp tubes are smaller than power amp tubes. A preamp tube is roughly the diameter of a cigar and about 1/3 the length. Here is a photo of a 12au7 tube, which is the type we use in Backert Labs linestage preamps:
Although preamp tubes get quite warm, they do not get as hot as power amp tubes. Preamp tubes also have less energy (voltage and current) going through them than power amp tubes do, in most cases. For these reasons, preamp tubes usually last longer than power amp tubes.
So How Long Do They Last?
With all of that said, the main factor that determines how long your preamp tubes will last is the design of the preamp.
Tube Life In Preamps: Other Brands. First, we will talk about the life expectancy of tubes in other brands of preamps. Other manufacturers sometimes run their tubes hard, which shortens tube life. You might expect the tubes in a non-Backert Labs preamp to last something like 2 to 8 years, although shorter and longer times are possible. We have heard from several music lovers who were at the “end of their rope” because they had a famous name-brand preamp and the tubes were dying quickly, lasting around 3 to 6 months. (In one case, a customer told us that a new pair of tubes had only lasted 6 weeks.) They would ask us to modify their preamp by inserting the Backert Labs amplification circuit, to extend tube life. These mods were successful, although today we are unfortunately too busy making new preamps to do these modifications on other brands.
Tube Life in Backert Labs Preamps. At Backert Labs, our preamp designs run tubes very gently. We are not aware of any other brand that runs tubes more gently than we do. (And we have seen many other brands.) In our preamps, tubes last an exceptionally long time — in fact, we have never seen a tube in one of our preamps “die of natural causes.” Of course, it’s possible that it has happened in a customer’s system, and we did not hear about it. But so far, we simply don’t see our tubes expire.
Again, the tubes in Backert Labs preamps don’t last this long because of the tubes themselves. It’s because of the circuit in our preamps that drives the tubes.
Do we purposefully design our preamps so that tubes will last a very long time? Actually, no. We design them to run the tubes at their most linear parameters, to obtain the very best possible sound quality. It just so happens that these levels of voltage and current are also very forgiving and gentle on tubes. It is a happy coincidence.
This is why we say, if you buy a Backert Labs preamp, you probably won’t need to worry about the tubes at all, because it’s very possible that the tubes will outlast all of us.
