An Elementary Understanding Of Tubes

While tube amplifiers are often considered the Holy Grails of gear, most players don't actually understand what creates that warm, thick tone which they appreciate and love. In this column, learn about what tubes are, how they operate, how to care for them, and why they create the sought-after tone.

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Authors Note: While this article will explain the characteristics of tubes and how to check for signs of wear, it will not go in-depth on how to change or modify amplifiers. Working with electrical equipment is dangerous and should be left to professionals, and due to the nature of high-voltage amplifier components, this article will not recommend or endorse any modifications or maintenance. All players know that the tone produced by tubes (or valves, in British English) is most often considered to be the best type of tone. Warm, full, and rich, tube-driven tone is the stuff of professionals. The simple pieces of 20th century technology are found in radios, televisions, and even early computers. And of course, these vintage components can really make a guitar scream. And while many players swear by tubes, few actually understand what they are and how they operate. In fact, many players don't know how to take care of tube amps. After reading this article, one should understand how their tubes work, and in turn, appreciate these precious inventions. Vacuum tubes were invented in the early 1900s. John Ambrose Fleming, a British scientist, placed an electrode in an incandescent light bulb and studied how an input alternating current would be converted to a direct current against the positive electrode while the light was on. Fleming's design was adapted for use in telegraphy and communications, and is still used to convert currents in modern electronics. In 1907, New York native Lee de Forest found that by adding another electrode grid to the bulb and applying the telegraph's signal to the grid, a more sensitive device could be conceived. A vacuum tube in the simplest form uses a heated filament, such as one found in a light bulb, to amplify or strengthen a signal. As the filament is superheated, electrons are released off the filament, and the current is channeled one way towards a wire grid. The grid is a sensitive detector of the signal, and can essentially allow the signal to be amplified to a more usable, more intense signal. Of course, the key to the signature tube sound can be attributed to many factors. The signal naturally flows through less parts than in a solid state amp, it gets a considerably noticeable aural quality when passing through tubes and an output transmitter, and some even say the way that the signal is clipped when the tubes are overdriven is something that solid state amps just cannot replicate. So how does a tube's operation affect an amplifier? Of course they impact tone, but how is their usage different than that of solid state components? Why do tube amps require extra care and maintenance? A tube's filament must warm up, just like a light bulb's. Due to the size and complexity of the tubes, however, it's not instantaneous like when a light switch is flicked. Larger tube amplifiers often have both an on/off switch and a standby switch. Before playing, it is better to turn on the standby switch for a few minutes to allow the tubes so warm up. A cold filament will be pushed harder, reducing the lifespan of the tube. And just like a light bulb, a hot tube is fragile. The filament is superheated and is not very shock-absorbent, so great care is required when moving a hot amp. In fact, it's recommended to just let the tubes cool down to room temperature (taking approximately 10 minutes) before moving them. Glass of course becomes more brittle with heat applied, so caution must also be taken so that the glass does not break. A single, miniscule crack can let in air, ruining the vacuum and the tube. And (again with the light bulb analogies!) of course, tubes can burn out. There are a few warning signs that a tube is reaching the end of its life span that players can look for, however, which can save them the pain of having a tube fail during a show. Most amps have fuses in them as a safety precaution. A dying tube draws more current to run, and repeated blown fuses can signify a tube problem. Another common problem is a high pitched, whiny noise (pre-amp tube) or a low rumbling noise (power-amp tubes) that is produced when the amplifier is turned on. This is often a side-effect of an inefficient, worn tube. In general, tubes last about one and a half to two years with average use. Hopefully, the history, science, and care of tubes is a little more clear. A little appreciation should be shown for this sacred piece of vintage technology; which outdated, it can never be replaced, and will be coveted by players for quite some time. Historical Sources: Barbour, Eric. "How Vacuum Tubes Work." Vaccum Tubes.net. 12 Jul 2009.

25 comments sorted by best / new / date

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    dylanfromearth
    SpeedLives wrote: Before playing, it is better to turn on the standby switch for a few minutes to allow the tubes so warm up the manual for my blackstar ht5 specifically says be sure to turn the standby switch to on no later then 30 seconds after the power switch is turned on, or else you risk damaging the tubes. also i think the everything you need to know about tubes thread says don't let it "idle" (standby off power on) for more then a minute or so, or else you risk damage as well.
    i have a peavey tube amp that i leave on idle all winter because that part of the house gets pretty cold, your statement is false
    fburns
    SLD.Potato wrote: That's what I was afraid of when I first got a tube amp, but they're really not hard to work with. Just don't throw the amp down a staircase and you won't have any serious problems.
    also if you get anythin over 10W in a good valve amp (spot the brit) you'll need an attenuator for bedroom practice. damn they're loud! but you want the volume up loud to get the best sound out, so: attenuator!
    FretboardToAsh
    Seems like a very good article, should get stickied in the gear & acesoires forum to avoid the buggers every month askign the same questions.
    nacnudnai
    Kudos to those open-minded to see that people are entitled to use whatever amp their ears like. Quite simply, there is still a high demand for ss and in my opinion there are some great ss amps. It's just horses for courses though, when it comes to bass amps I like ss, but I prefer tubes for my guitar amps in most situations.
    DrPeppler
    Thank you so much for writing this column! I have a Mesa/Boogie Triple Rectifier and have been wondering why I was blowing fuses left and right. Thought there was a continuous power surge or something. Just to make sure, though; when I started blowing fuses, I switched from "High Power (silicon diodes)" to "Normal Power (vacuum tubes)" and I stopped blowing fuses. Was this because I am now running less power to the tubes, thus making it harder for them to draw more power to a "dying" tube(s), which would stop causing a fuse to blow? Also, my tubes are, like, at least three years old with daily use at moderate volumes.
    grem_roots
    As for buying valve (I think) the best thing to do is to take the damaged (or undamaged if you're just looking for a spare) into an electronics shop and ask for a valve of the same spec. It'll be about half the price of a branded marshall valve and is exactly the same. I heard somewhere that nearly all valves, marshalls included, are made in the same factory somewhere in Russia. Interesting article though. thanks for posting
    Blas3
    \m/[-_-]\m/ wrote: at first when i saw this thread i saw it said 'An Elementary Understanding Of Pubes'. i lol'd hard.
    LOL!!!!! 1 for you
    \m/[-_-]\m/
    at first when i saw this thread i saw it said 'An Elementary Understanding Of Pubes'. i lol'd hard.
    whitenihilist
    When people say "damaged tubes" (i.e. idling your amp, not letting it warm up) they don't mean that it will "meltdown" or "explode". They mean that the tubes will have a considerably shorter life, depending on how often you do damaging things. That is the only real drawbacks of tube amps: having to pay for replacement tubes. That being said they are not that expensive, I have a Crate Palomion V32, it has 3 preamp tubes and 4 power amp tubes and the average price of a complete retubing is about 80-100 dollars. And with proper care tubes can last years.
    The^Unforgiven
    justinb904 wrote: arguing over something so opinion based is simply retarded.
    Arguing over the internet in general is like competing in the special olympics, as in even if you should win you're still a retard. Anyway, totally agree, tone is a very subjective matter, and it's not all about what kind of circuitry runs your amp. Don't ever see anyone bitching because of Dimebag largely having relied on ss -amps instead of tubes, now do you?
    metallicafan616
    tube is american, valve is british. and The Judist, you are tone deaf. VERY tone deaf if you think a bandit has good tone or sounds anything like SRV
    hawk_kst
    metallicafan616 wrote: tube is american, valve is british. and The Judist, you are tone deaf. VERY tone deaf if you think a bandit has good tone or sounds anything like SRV
    Erm being tone deaf doesn't actually mean not recognising a good tone... it's refering to pitch...
    Lauke_101
    I might be wrong and hey, I'm not a native speaker of English, but I always thought the word valve was American and tube was British.
    Kevy Absolution
    Good call NemX, my mistake. Yeah, power first and allow the tubes to heat before engaging the second stage.
    NemX162
    I think you mean to say to turn on the power with the standby switch off then, switching it on. Turning the standby on without the power will do nothing, on my amp at least.
    SpeedLives
    Before playing, it is better to turn on the standby switch for a few minutes to allow the tubes so warm up the manual for my blackstar ht5 specifically says be sure to turn the standby switch to on no later then 30 seconds after the power switch is turned on, or else you risk damaging the tubes. also i think the everything you need to know about tubes thread says don't let it "idle" (standby off power on) for more then a minute or so, or else you risk damage as well.
    Morning Star
    So basically don't do anything slightly out of the ordinary or it will explode. I know they sound great but I would be constantly terrified of doing something that would cause a meltdown. Not good for an OCD spaz like me.
    justinb904
    Before an argument/mass flaming breaks out that I'm sure would be a great annoyance to the cc's, it might be good to remind our selves that good tone is largely based on our opinions and arguing over something so opinion based is simply retarded. If someone likes the tone of an ss amp more power to 'em. More on topic, tube amps aren't hard to take care of as some of you seem to imagine. The whole on/off/standby deal is just to help preserve the life of the tubes. It's not like if you don't do it exactly right your tubes will explode. Other than that just treat it with the same care you would any other amp and you shouldn't have any problems.
    SLD.Potato
    Morning Star wrote: So basically don't do anything slightly out of the ordinary or it will explode. I know they sound great but I would be constantly terrified of doing something that would cause a meltdown. Not good for an OCD spaz like me.
    That's what I was afraid of when I first got a tube amp, but they're really not hard to work with. Just don't throw the amp down a staircase and you won't have any serious problems.
    The Pickle Man
    The Judist wrote: I can't be bothered with valve amps. I just play solid state amps. I don't see why I should have to get one just to follow a norm. I'm saying anyone should do what they want to do, as long as it causes no harm or loss to others of course. I just plug my Yamaha into my Peavey Bandit. Some people say my tone is like SRV. That's enough for me.
    That's not a very intelligent series of words you've put together there. If you can't be bothered with tubes, well, you're not much of a guitar enthusiast. I know for a fact that the Peavey Bandit is a piece of shite, and anyone who tells you you sound live SRV has to be a retard.
    enselmis
    it doesnt really make that much difference. it's not gonna murder you tubes while it's idoling, they'll wear, but slower than when its on full power.
    The Judist
    I can't be bothered with valve amps. I just play solid state amps. I don't see why I should have to get one just to follow a norm. I'm saying anyone should do what they want to do, as long as it causes no harm or loss to others of course. I just plug my Yamaha into my Peavey Bandit. Some people say my tone is like SRV. That's enough for me.