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Return of the Vacuum Tube
sciencehabit writes "Peer inside an antique radio and you'll find what look like small light bulbs. They're actually vacuum tubes — the predecessors of the silicon transistor. Vacuum tubes went the way of the dinosaurs in the 1960s, but researchers have now brought them back to life, creating a nano-sized version that's faster and hardier than the transistor (abstract). It's even able to survive the harsh radiation of outer space."
...to the phrase "a series of tubes."
Now I can have a tube amp in my mp3 player.
Give me Classic Slashdot or give me death!
These are still widely used in some of the best amps out there.
Almost every TV broadcast transmitter and most FM radio broadcast transmitters still use vacuum tubes for the high power output stages. Every microwave oven uses a vacuum tube to produce the microwaves. Most radar transmitters use vacuum tubes for the output stages, and often for signal generation too. The fact is that semiconductors have simply not been able to catch up to vacuum tubes for high power applications at UHF frequencies and above. 1960's technology still reigns supreme.
I am a geek attorney, but not your geek attorney unless you've already retained me. This is not legal advice.
aren't they just called "tubes"?
low power, high frequency, rugged, ... I say, these things might be useful
And they are used in some of the best old-school reel-to-reel recorders. I don't know if they are making new components with tubes, but older tube pre-amps for Ampex and Scully tape recorders are prized by some audiophiles for their "warm" sound. They are also great for creating distortion...over-driving tube pre-amps creates some nice distortion effects which digital components would just clip.
But (and I'm speaking as someone who has been out of radio and audio for many years...I own a hardware store), from what I've seen and heard there are some pretty awesome digital programs that can duplicate nearly any pre-amp ever made. Based on what my daughter can do with her Mac (Protools, FInale, etc) I am pretty impressed at the sounds that can be processed even in a home environment with no need for tubes.
On the other hand, my tube pre-amps do keep the basement warm. :)
"We make our world significant by the courage of our questions and by the depth of our answers." Carl Sagan
Keep seeing all these whippersnappers nowadays wearing the same clothes I wore years ago.
You should have thought of that before you donated them.
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There is 1) no vacuum and 2) there is no "tube." While there is an electron emitter, this device should be called a MOSFET.
Take the cheese to sickbay, the doctor should see it as soon as possible - B'Elanna Torres, "Learning Curve"
From a radiation engineering point of view, outer space is not the most stringent environment. It is actually significantly more forgiving than a lot of useful earth orbits or the radiation belts of the gas giants (but of course, you can hardly replace a failed transistor in space...).
These "vacum tube like" diamond field emission devices have shown radiation tolerance from 10 to 100 Mrad (1 MGy in SI units), so we are more talking about the levels required for operation in nuclear reactors or close to the beam of particle accelerators.
Actually an open heater was NOT the way most tubes died. The coating on the cathode that emits electrons when heated gradually decays and emission drops off to the point that the tubes transconductance is too low for it to operate. But the heater rarely burns out, at least not in indirectly heated tubes. Another way they die is that air gradually leaks in and the vacuum becomes too poor. The silver flashing on the side of the tube will then turn a milky white as the chemical "getter" that absorbs air has absorbed all that it can. Once the getter coating is depleted the tube will become gassy. A tube can also die from shorts when closely spaced elements break loose from vibration and touch. Over heating will soften the elements and cause the same effect. Tubes can handle a much higher percent of overload than solid state devices however. Tubes computers were never faster than solid state ones even if the tubes themselves were faster. Because of their size the total wiring in a tube computer is much longer than in a solid state system. In transistors it is the "holes" in the crystal structure that "move" and the speed of light in silicon is lower than in a vacuum for electromagnetic waves. Still these waves have less distance to propergate in an IC than a bunch of interconnnected tubes. Finally note the description of this new tube technology, it is really a "vacuum state" IC. I always wondered when nanotechnology would be applied to thermionic "valves" (as they say across the "pond").
Hey, it's ok cffrost. Just calm down.
We all know dinosaurs still exist.
The real Sig captains the Northwestern. This one captains
I have a few devices that use vacuum tubes and I have not encountered a tube that heats up but does not work due to low emissions. They all either work acceptably or not light up at all (a tube full of air also does not light up, at least from the nominal heater voltage). Maybe in the USSR made tubes the heater is the first to go.
Then again, I do not have a tube tester (always planning to build one, but always find something better to do), so maybe most of the tubes in my devices have really low emission, but the devices work OK, so I don't bother replacing the tubes with unused ones to see if the performance changes.
"Tales of the Flying Mountains" by Poul Anderson
It's a collection of short stories about the "Asteriod Republic" wrapped in a frame of the first interstellar flight. One of the stories features a military vessel whose electronics were built with "TEMMs" - Thermionic Emission Micro-Miniaturized - featured for its radiation hardness.
The living have better things to do than to continue hating the dead.
The article is painful in some aspects
Electrons move more slowly in a solid than in a vacuum, which means transistors are generally slower than vacuum tubes; as a result, computing isn't as quick as it could be.
I'm flabbergasted.
Meyyappan, who co-developed the "nano vacuum tube," says it is created by etching a tiny cavity in phosphorous-doped silicon. The cavity is bordered by three electrodes: a source, a gate, and a drain. The source and drain are separated by just 150 nanometers, while the gate sits on top. Electrons are emitted from the source thanks to a voltage applied across it and the drain, while the gate controls the electron flow across the cavity
This is really a vacuum tube if you add a high dose of immagination. Really
The separation of the source and drain is so small that the electrons stand very little chance of colliding with atoms in the air
Makes me wonder if tunneling plays a part here
how long until
If you're' looking for that 'classic' sound with its harmonic distortions, then yes.. if you're looking for accurate sound, then no.
When Viktor Belenko defected to Japan with a MiG-25 fighter jet in 1976 (state of the art Russian aircraft back then, meant to counter our F-15) it was discovered that most of the electronics onboard the aircraft were built with micro-miniature vacuum tubes! The reason being that the fighter jet was designed for presumably nuclear war situations, and the Russians wanted to ensure that EMPs from nuclear explosions would not permanently damage the electronics, so the aircraft could still fly and fight even after exposure to any nearby nuclear explosions that were still distant enough to not physically destroy the aircraft.
When I was a young kid, my mother would fix the TV by pulling out all of the TV tubes, wrapping them in news pages, and then carrying them all down-town to a big drug store which had a coin-operated tube-tester machine. She'd plug them into the matching slots one by one and see which ones were good and which were sour. I couldn't help her because I was too short.
Then she'd go to the back of the store to find matches for the sour tubes based on the codes printed on the tube slots. (Often the label was worn/cooked off the tube itself such that the slot labels on the tester were the only way to tell.)
I'd generally consider her a "technophobe", but she did it in a very routine fashion as if she'd done it dozens of times before. People just got used to tubes back then.
At least TV's were partly repairable. Now the repair costs are often more than a new TV. Oh, and Get off my lawn!
Table-ized A.I.
I believe that anyone younger than 30 now stands a damn good chance of never seeing a vacuum tube or even know of their existance.
Wrong.
If they ever attend a rock concert or watch a video of one (or if they ever take up electric guitar or bass) they'd see walls of them. Usually with big script logos that say "Marshall" or sometimes logos that say "Fender", "Soldano", or "Mesa-Boogie", with a few other brands that are less well-known and typically considered more "exclusive" like Matchless, Framus, Dr. Z, Top Hat, Divided by 13, Bad Cat, Victoria, etc etc.
All the top guitar-amplifier makers' top-of-the-line pro-level models brag of being "all tube". DSP has not yet been able to equal the tone, "feel", and response to the player's nuances that vacuum tubes exhibit. It's really, REALLY hard to model all the variables that affect the sound of an electromechanical device like a vacuum tube with digital signal processing.
I build and sell custom vacuum-tube guitar amps myself, as well as provide service and repair for vintage & modern tube guitar and bass amps. I can also occasionally be found on a stage in a club, or on a festival stage somewhere, playing guitar. I've been doing both for about 4 decades now.
Strat
Progressivism (aka US 'Liberalism'): Ideas so good they need a police/surveillance-state to enforce.
I looked for the heater of the tubes as well, replacing once that weren't glowing orange;
99% of the time it fixed what was wrong.
I was young and repaired TV's to sale for cheap. If all the tubes heaters were working;
I took them to the local grocery store as they had a tube checker (as did most places at the time).
If the tube showed bad, I'd picked up a replacement at Radio Shack, more often than not making a profit.
And the funny thing that it was even not that "secret" of a technology (application was, of course!), I remember reading about "new life of a vacuum tube" in Soviet magazine for technically-inclined kids ("Yunyi Technic") sometime in my early teens, late 70s - early 80s -- I definitely remember reading about thin-film integrated vacuum tubes technology, and, I think, about it's rad-hardness (not using that word, of course, or better half of the reason why it is important ;-) ).
Paul B.
Thanks for modding me down jackass. You could have INFORMED me of that fact without punishing me with a -1 whip. (And if it wasn't you, then I direct my comment to the other fucker that did it.)
You can't post and moderate in the same article. Posting removes all your moderations in that article.
A good modern transistor amp can do precisely what a good amp should: Disappear. They can have distortion low enough, noise low enough, be linear enough, and so on that they don't introduce any audible artifacts of their own. You can swap well built ones around and hear no difference.
That's what you want out of a good reproduction amp, just a wire with gain effectively. It should introduce no changes of its own. Of course you can't have one that is flawless and does NO changes but you can have one that the changes are so low you can't hear them.
Don't have to break the bank for it either. You don't have to but some $5000 monstrosity, a couple hundred dollars and the right design gets a transistor amp that just vanishes.
Now if there's a reason to want the distortion, then maybe you want a tube amp. Electric guitar can be such a case. The signature sound they have doesn't come from the guitars themselves, they sound very flat and boring plugged right in to a mixer. It is the speaker and amp that give them their sound. You take tubes and drive them in to the non-linear range on purpose.
Fair enough, but not the goal of reproduction. Also these days, it is getting cheaper just to DSP things. We have a rather good idea of how various things create the sound that they do and we have powerful and cheap DSPs that can throw math at the audio signal and make the same thing happen. Often the way to go, particularly since you get flexibility.
I have replaced a total of two tubes in my devices, both of them were dark. One was a tuning indicator (I got the radio with it bad) and the other was a Soviet version of EL84 - that worked for a year or so and then burned out. In all of those devices I have not seen a tube that does not work but lights up.
Also, the tubes in my headphone amp are on at least 12 hours per day (sometimes I do not turn it off for weeks) and in use 6 years already and they still work. One tube (it was used when I got it, it has a black spot (burn?) in the getter) sometimes starts to act up (becomes noisy) but a slight tap gets it back in line. Granted, those are low power tubes (two 6N23P/6DJ8 and one 6N2P (kinda similar to 12AX7)) but still, they are quite long lived. The 6N23Ps are not even military grade.
What the hell are you talking about? Many tubes have multiple gain devices within the same envelope. I remember building a hybrid tube/MOSFET headphone amp a couple of years ago using a single 6DJ8, which has two triodes in it. There's no doubt the motherboard in question only used the tube for VAS and not as an output stage, so there's no reason to use a push-pull configuration.
"Politicians and diapers must be changed often, and for the same reason."
It has more to do with reputation than with "can't be done otherwise". A 50 cent-a-pop DSP probably has enough power to simulate the good ol' vacuum tube sound.
Well, I guess we'll have to agree to disagree here. For 40 years I've worked at music stores and been in bands, never mind being an amp tech/designer/builder, even worked in avionics and military-related high-end electronics systems, heard many of the very best DSP studio rack processors made costing many thousands of dollars, and my ears and everything else I know and have learned so far during all this time convinces me that, although DSP has gotten much, much better compared to even 5 years ago, it hasn't arrived yet at the point where the human ear can't tell the difference.
DSP guitar tone, clean or overdrive/distortion/effects, does not sound like real tubes *yet*. They will probably get there, I'm not saying it won't happen, maybe quite soon. It's just not there yet.
There's one solid-state amplifier made starting in 1975 that sounds great for jazz guitar. The Roland JC-120 Jazz Chorus 120 amplifier. Beautiful clean sounds. It does have a distortion function, but *nobody* used it once they heard it! :)
Don't get me wrong. If you're in a local small-town working bar/dive band that is mostly there for the $40 to $80 a man per night, and not trying to impress anyone with your tone except the bar owner...just enough, that is, to pay you and keep you on the booking rotation, and you don't want to carry any more than absolutely necessary nor tie up more money than you absolutely have to in an amp, something like one of the "Line 6 Spider" combo amps will "get it done". Sorta like when old people...well, never mind. :-/
Those type of DSP solid state amps are also great for those just starting out, as it has a bunch of effects in software already, no effects pedals or rack effects, cords, etc to bother with, and they're dirt-cheap as amps go. If it breaks, throw it away and buy another just like a disposable lighter.
And yes, I do prefer the vacuum-tube amps, not only because of the sound, but also the warm feeling of old electronics :)
Here's my personal amp that I built recently.
http://i62.photobucket.com/albums/h103/stratman_el84/Testament%2030/cabhead03.jpg
4 tubes total. two 12AX7 dual-triode preamp tubes (one a parallel-triode preamp gain stage, the other is the "long-tailed pair" style dual triode inverter/driver tube) and two KT66 beam tetrode power tubes in cathode-biased push-pull Class AB, producing around 30 watts. Volume and Tone controls, Standby/On and Power On/Off toggles. That's it. It sounds fantastic. You can't find a Volume/Tone control setting combination that sounds bad. I keep finding wonderful new tones and sounds almost every time I play it.
The sealed-back dovetail pine cab finished with Tru-Oil gunstock finishing oil with a Baltic birch plywood baffle has a pair of Celestion G12T-75 12-inch 8 Ohm guitar speakers wired in parallel for a 4 Ohm total impedance. It sounds absolutely gorgeous. Combined with that amp, some serious guitar tone-heaven.
I took the amp head into the local Guitar Center store shortly after I'd finished it. They had *nothing* that sounded anywhere near that good. The manager finally noticed the small crowd gathering, and (gently) asked me to cease after he started hearing a couple people asking if I sold amps like that one. :D
Oh, and since you mentioned a "warm feeling from old electronics", here's a little something that's sure to make wherever it is at just a little warmer. And louder. A *LOT* louder.
http://i62.photobucket.com/albums/h103/stratman_el84/Junk/monster.jpg
Progressivism (aka US 'Liberalism'): Ideas so good they need a police/surveillance-state to enforce.
The tube on the AOpen mobo was a 6DJ8/6922, not a 12AX7.
The 6DJ8 is also a dual triode, but it has much higher transconductance because it is a frame grid design. Those tubes were widely used as input amplifiers in vintage Tektronix scopes because of their low noise and high linearity.
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I believe that anyone younger than 30 now stands a damn good chance of never seeing a vacuum tube or even know of their existance.
Wrong.
If they ever attend a rock concert or watch a video of one (or if they ever take up electric guitar or bass) they'd see walls of them.
I've never seen a human pancreas, but I've looked at untold thousands of people during my life. If I hadn't done biology at school, I'd probably not even be aware that there was such a thing as a "pancreas", even after looking at all these people.
The previous posters point is that most modern geeks don't know about tubes. Most modern computer geeks aren't guitar geeks (although some of us are -- I even built my own electric guitar once!)
Got them moderator blues I blieve I walk out the do', With these mod-points I been gettin', I 'most never post no mo'
That radar caused tremendous interference on the ham short wave bands. It got the name "the Russian Woodpecker" since that is what the interference sounded like, a flock of angry woodpeckers.