I've got a Fender Hot Rod Deluxe, I've had it for a couple years and I wanna know when to replace the tubes.
TBH, it takes some pretty worn out tubes to noticeably sound like shit. The change is typically so gradual you don't notice it until you put in a new set.
Rhodes Gemini
Fryette Ultra Lead
Peavey 6505
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Gibson R0 Prototype
EBMM JP13 Rosewood
Fender CS Mary Kaye


(512) Audio Engineering - Custom Pedal Builds, Mods and Repairs
Do it when your tubes start to feedback uncontrollably like one of mine right now. Really thats the only way to know when to replace them
I have A Marshall 1987x that I have had for about 12 years, and have not had to replace the tubes, yet. It is all Original, to say the least. But like these guys say, "when it starts to sound like crap, then they should be replaced" But at the end of the day, new tubes will always sound better than older ones. Why, because they are new! So, truth be told, there is no real "time frame" to change the tubes, it is solely based on what you are looking for, in your sound. If you are happy with the way it sounds now, then you are doing ok. But if there is something in particular you are looking for, like, lets say, more midrange, they build a tube set for that, if you want your Fender hotrod deluxe to sound like a vox ac30, U guessed it! They make tubes for that too!
Just something to ponder... changing, and rebiasing tube amps, is a sound, but "pricey" investment. So, be sure to do your homework, on what type of sound, and feel, you are looking for when considering your tubes. My best luck have been with groove tubes, and they are pretty expensive, but as always, you get what you pay for, in terms of quality and performance.