Best Way To Maximize Preamp Tube Life?

Don Sachs here...   turn them off if you are not going to listen in the next 30-60 minutes.   Honestly, tubes last a LONG time in my gear.  I run them conservatively.   Now and then a tube dies early, but that would happen anyway, no matter what you did.   Leaving things on just creates a lot of heat you don't need over many hours and wears tubes out.   Turning a tube system on 2 or 3 times a day doesn't hurt it all.  My power amp and integrated amp have a very soft turn on sequence that is easy on power tubes.

Pulling tubes and running a circuit without all them in there is absolutely the WRONG thing to do unless you know exactly how the circuit is designed. You can destroy a filament supply (or a tube in it), or overwork a B+ (high voltage) supply if the circuit is designed to have all the tubes in it. I have rebuilt well over 500 pieces of vintage tube gear. On some of it you can pull tubes and there is no effect, on others you better not do that except for a brief few second test on the bench to measure some voltages. If you are not using the phono section in some preamp, then get some bargain basement cheapo 12ax7 (or whatever tube it uses) and plug it in there. If you pull tubes and run things the B+ may be high due to less loading. If the circuit is poorly designed or has parts running close to their max spec, then you could see early parts failure. Again, it all depends on how the unit was designed and built. Many times I have seen things with 475 V on a 500 V rated part. You pull a tube perhaps you are now looking at 490V on that part. I don’t design or build things that way, but I have seen lots of gear that runs parts at the ragged edge. Jim McShane taught me to never run anything over about 70-75% of rating for that reason. Very good advice. You have to take into account the turn on surge as well. A lot of times your B+ may be 420V and the parts are 500V rated, but at turn on before the tubes warm up and conduct you may see 495V and then it drops. Again, if you start pulling tubes you alter that. So you darn well better know what you are dealing with before you run it without all the tubes in it. Rant over......

My experience is that a good tube circuit will sound great in 10-15 minutes after turn on. Leaving it on 24/7 buys you absolutely nothing except very poor tube life. Turning something on 2 or 3 times a day doesn’t hurt it at all unless it is very poorly designed.