As far as how often tubes have to be replaced depends on how you use your equipment. I leave my tube amps and preamp on 24/7. My tube amps are 4 watts so heat is not a major concern.
I replace the whole preamp set three times a year at a cost of about $45 per set; (2)12AX7 (2) 12AU7 and (1) 6922. I use Ei Yugo's, East German RFT's and Russian Military 6922's. (FYI - the Russian Military 6922's equal the performance of the (much) more expensive NOS Telefunken/Siemens/Amperex; I have listened to them all).
The tubes in my amps get replaced about once a year at about $150 per set; (2) 2A3's (NOS RCA's), (2) 5692 or 6SN7 and (2) 5Y3's.
The reason I leave them on all the time is because tubes sound better after they have warmed up for 48 hours. Just my preference - and the way I chose to spend money. I keep a stockpile in case a tube fails earlier than expected.
Rule of thumb: figure 2,000 hour life span for tubes.
I replace the whole preamp set three times a year at a cost of about $45 per set; (2)12AX7 (2) 12AU7 and (1) 6922. I use Ei Yugo's, East German RFT's and Russian Military 6922's. (FYI - the Russian Military 6922's equal the performance of the (much) more expensive NOS Telefunken/Siemens/Amperex; I have listened to them all).
The tubes in my amps get replaced about once a year at about $150 per set; (2) 2A3's (NOS RCA's), (2) 5692 or 6SN7 and (2) 5Y3's.
The reason I leave them on all the time is because tubes sound better after they have warmed up for 48 hours. Just my preference - and the way I chose to spend money. I keep a stockpile in case a tube fails earlier than expected.
Rule of thumb: figure 2,000 hour life span for tubes.