When to replace preamp tubes?

Wow Virdm, I have read some tube POWER amps blow like you think a tire does, my amp would not go that way but many here purchase those poorly designed amps. I had a kt88 stop working, but I do not know when it stopped I just noticed the amps sound was unbalanced. Now that is a tube amp. If you were to look at the Continuous Automatic Bias System in the new VAC amps all of this talk is a waist of time.

But the original post talked about a PREAMP tube, so you are saying a 12ax7 will blow like a tire?

To the original posters question: 12-type tubes are like a light bulb, I turn off the light bulb when I leave a room, then turn on the light bulb when I enter a room, just like tubes, I turn on the tube when I want and turn them off when I am done.

Keep an extra set and don’t become paranoid like so many others

This is why people fear tube equipment, little boys with little toys. My mother used tube amps and preamps, my grandmother used tube equipment and all was good. In my little picture next to my tag is the high end turntable from my grandmother, and it still works.

If you are willing to spend 10 minutes changing a set of tubes every 5-10 years or so, you will be rewarded with better sound, in my opinion.