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Do preamp tubes need periodic (regular) replacement as power tubes do? I got a mixed answer from Mesa Boogie on this question.
Thanks

They usually last a really long time. Play them until your amp starts to sound bad. Then take a pencil and tap on each tube. If one of them goes nuts, it's gotten microphonic and needs to be replaced. I'd play them until your ears just aren't happy.

Rectifier tubes last a really long time. Power tubes seem to be the first to go.

you can figure about 5000hrs for new production tubes and about 10khrs for NOS types, for preamp style tubes. output tubes last as long as hard as you play. play hard, they wont last long. a good 6L6 type, expect about 2000 hrs.

germ

If your looking for more a general time of replacement its about after 2 power tubes replacements, they should probably last longer.

Because they last quite a while, keep a selection of your favorite preamp tubes around so you can insert them in your favorite amps and see how they change the sound.

Tubes are simply so so fun.

As mentioned, pre-tubes usually last for awhile. It's a pass/fail/work-doesn't work kind of thing.

Thanks for all the info.