Ah, tube amplifiers. Most guitarists swear by tone, and the greatest musicians of our time, and our parents' time, have used tubes to create their envious tones. So why on earth has the world switched to transistor use for amplifiers, if tubes give off an amazing vibe?
Well, there are two main reasons for this: cost and care. One salesman described tube amps to me wonderfully; having tubes are like having kids. They whine, complain, can be a pain the ass, cost you money, and steal away from your personal time.
But tubes, just like children, can reward you with great tones, not to mention a wonderful resale value, and prestige. Bragging about buying a Marshall JCM800 is far more rewarding than bragging about a Peavey Rage 30, right? Right.
So, really, if you want to be a good parent for your amplifier, start by treating your amp with respect. Make sure you use an amplifier cover, keep drinks off of the top, don't use it as a coffee table, footrest or seat, under any circumstances.
But caring for your tubes goes beyond that. So, to start things off, here are basic things you can do to extend the life of your tubes:
Use The Standby Mode
Ever wonder what "standby" meant? Well, its a state of equilibrium for your amp - not on, and not off. The speaker remains inactive, but preamp and poweramp tubes are given a warmup. Some people will suggest you have your amp in standby before and after playing for two minutes, but other sources suggest 30 seconds. I'd suggest you keep it in standby for an absolute minimum of 1 minute, before and after playing. If you'd been playing for a while, keep it in standby until everything has cooled down. This helps to increase the life of your tubes dramatically, if you do it each and every time you play.
Don't Get It Wet
Well, obviously. Don't get your amp's cover wet, because this degrades the cover, ruining the resale value. If you get it really wet, the moisture can seep into the wood, ruining the tonal balance of the wood. If you get the electronics wet, you've really messed it up. Remember, never leave any drinks on top of your amp. Never turn your amp on if its wet under any circumstances, and never, EVER let moisture seep into the back. Stuff like this will cause short circuiting, leaving you with a hefty repair bill.
Don't Get It Cold
How would you feel if you were left in a car in 0 degree temperatures for 2 hours? Not too happy, obviously. So why would your amp be any different? Well, its not. If you must get your amp cold, always leave a cover on, and make every attempt to keep it as warm as possible. Remember the water warning? Well, if its cold enough, water vapour will collect on your amp. Not cool. Also, refer back to using the standby mode. The point of standby is to let your tubes warm up so they aren't exposed to extreme temperature changes. Make sure your tubes & components have fully adjusted to room temperature before even turning on standby. Do a quick check to ensure no water vapour has collected on any wiring components.
Keep Your Eye On It
Always keep your eye on your amplifier in public places. Whether its a small school gig, or you're in a bar, make sure nobody's coming up and touching your amplifier. Don't let it stay unsupervised, and always let a trusted friend keep an eye on it, or pick it up and move it. Simply put, people aren't as innocent as you'd like them to believe. Most people don't understand the concept of tubes and their delicacy, so you better be moving delicate equipment by yourself, or at least by someone who knows what they're doing.
Make sure your amp is connected to a speaker (or a dummy load) at ALL times. If you notice that the speaker signal has been cut for some reason (an uncommon occurance nowadays, but keep an eye out if you're using an old amp) turn your amplifier off immediately. If the speaker has been disconnected for some reason, the power transformer & power tubes will be destroyed because there is no resistance for the signal to be applied to.
Of course, the number one rule for tube amp care is to not let anyone borrow your amplifier. This has to go without saying, because if something does go wrong while its in the care of someone else, they may not know anything's gone wrong, and continue to use the amplifier. See anything wrong now? Of course. If a burning smell emits from the back power tubes, the user may not think anything of it, but it could turn out to be a serious problem if left unattended. And, of course, they may not even adhere to the rules stated above.
A good tube amp can last for years and years. In fact, if your tubes are carefully paid attention to, they can last for many years, while they won't sound as good as they should. With average playtime, power tubes need to be replaced about once a year or so, but if you're playing a lot, they may need to be replaced after 8 months. When your tube amp starts sounding loose, and slightly off, all it needs is a power tube replacement.
Generally, when tubes lose their vacuum, they turn white, so you'll know to replace the tubes. Preamp tubes don't need to replaced as often as power tubes, because they hardly receive a workout when the amp is on. Power tubes, however, are really pushed, especially on distortion.
Thanks for reading my article, and I hope anything you've learned serves you well.
Sincerely,
- Backup Guitar
/ my profile 
And I'll back that a Rage 158 Sucks.