yes tube gear does run hotter--- the tubes do generate heat..
there are units with and with out exposed tubes ---
check out our showcase on audiogon ...
tubes can last as short as a couple of months -- if not biased right or a couple of years ... depends on usage ...
and tupes can cost various prices -- from $10 to a couple hundred dollars .. again depending on make ..model and manufacturer
In general, tube amps do run much hotter than class AB solid state. However, some Class A solid state amps run as hot as tubes.
There are many variables that will affect how long a tube last. That includes the design of the amp, the tube type, who made the tube, your listening pattern – do you keep the amp on all the time or only turn it on when listen, how stable is the voltage of your power outlet, etc… In other words, it is impossible to make a general statement about tube live.
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.
Tube preamps do not run hot at all.
I don't know how long tubes last, or their cost, as I bought my first tubed amp,a McIntosh MC 2000 some 8 months ago. A lot of tubes on this one, but I had a KRELL FPB 300 SS amp and I will tell you it ran WAY HOTTER than the Mac. The Krell sounded great, and made an even better space heater. I have found the heat from the Mac a non-issue and I have a rather small room. Plus the sound of the tubes...so smooth!
During the charity auctions, I bought a tube tester, A Hickok 6000A for about $250. We ran all of our tubes this past weekend and were really amazed at what we found. An entire eBAY shipment of crap, the tubes in the preamp - 1/2 were ready to be swapped out - they were in there about 6 months with 10-20 hours/week play. The answer? It depends.... We have tube amps, tube preamp and our CD player has a tube on the output stage, so a tester is a worthwhile investment.
Tubes are a wild animal, if you are into noodling around and wanting to really spend some time in this, tubes are a wonderful way to go and explore. We love the learning, the tweaking, the noodling around. If you want a system to sound the same, just like you like it, with little to no fuss, then stay away from tubes. This is just my opinion.
Best of luck !
If you love the sound of tubes (and make sure you do before getting into this), the occasional tube malfunction - more common in power amps than preamps - is easily outweighed by the positive. But bear in mind (as has been mentioned above), you're looking at continuing expenses over the years for tube replacement. Nothing horrific, but nonexistent with solid state. If you're new to tubes, it would probably be a good idea to buy from a local dealer you can trust so when you get strange whistling, squeaking, rushing (etc.) noises, the dealer can steer you to the problem and solution. Ultimately though, it's really only a tiny pain in the butt, and you'll learn how to diagnose problems (switch L and R channel tubes to see if the noise changes sides, for example) quickly. One last thing, though: if you're a bass freak, you may want to get a powered subwoofer, because tube watts are more expensive than SS, and bass needs power...I reached nirvana with tube pre and power and a REL sub.
A simple answer, Preamp tubes last for around ten years (12ax7,12au7etc).The small power amp tubes 12au7 etc again last around ten years. The big tubes due vary, example KT-88 last around 3-5 years and 300B tubes last about ten years. Older tubes are 25.00 to 75.00 per tube for the small ones and forget about the older 300b and KT-88. New tubes sound very good and work for most pre amps, and cost around 15.00 for small tubes and 35.oo to 50.00 for the big power tubes. If you want to keep your tube cost down, select a tube product that uses common tubes and not rare tubes, that will be hard to find in the future.
Sorry Gs5556 I have to disagree! There is NO WAY that Russian mil-spec sound anywhere near as good as some of the classic NOS tubes. Also, small signal (pre-amp tubes) should last 6,000+ hours (left on 24/7, these tubes should last AT LEAST one year...switching off when you're away or not listening for awhile and these tubes should be good for two to three years!) The Russian/Yugo tubes, as a general rule, DO NOT LAST AS LONG AS GOOD NOS TUBES!!! (Looser tolerances and quality control than premium NOS!) Ya gets whats ya pays for!
...just to qualify my statement - the Russian MilSpec/Ei Yugo/RFT's are better sounding in my CAT MKII preamp (and associated equipment and room) than ANY other tube combo. Nothing against the NOS tubes, just happens to be that way in my gear where the extra expense is not justified. Also, CATs eat up tubes faster than most tubed gear (CAT recommends replacement after 2000 hours or whenever the sound degrades).