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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."
These are still widely used in some of the best amps out there.
Don't forget guitar amps. You're not gonna get the same aesthetics out of silicon. The best amps all pretty much use vacuum tubes.
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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
Uh... Microwave ovens use a magnetron http://en.wikipedia.org/wiki/Microwave_oven#Design I've repaired many a Microwave ovens and I have never seen any vacuum tubes.
Too smart for your own good. A magnetron is a vacuum tube. Not all vacuum tubes are transparent. Hell, the "vacuum tube" in the article has neither a tube or a vacuum!
As long as we're quoting Wikipedia:
http://en.wikipedia.org/wiki/Cavity_magnetron
The cavity magnetron is a high-powered vacuum tube that generates microwaves using the interaction of a stream of electrons with a magnetic field.
Uh... Microwave ovens use a magnetron http://en.wikipedia.org/wiki/Microwave_oven#Design
I've repaired many a Microwave ovens and I have never seen any vacuum tubes.
Nathan
Indeed they do use magnetrons. And to quote from the first line of the Wikipedia article on magnetrons" "The cavity magnetron is a high-powered vacuum tube..." (my emphasis). Do you repair the microwaves with your eyes closed?
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1960's?
The amplifying triode vacuum tube was invented near 1907.
The transistor itself in 1947.
Well.. maybe. Or Maybe not. But Definitely not sort of.
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").
No, space is a far far harder vacuum than anything we can currently manage on-planet.
A vacuum tube still has between 1 million to 1 billion molecules per cubic centimetre, depending on tolerances. The best vacuum we can currently make has about 100k molecules per cubic centimetre.
Interplanetary space has about 10. Interstellar space has about 1. Intergalactic space has about 1 per cubic metre (10,000 cubic centimetres).
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So, why not combine dozens (or hundreds) of transistor output stages to get the equivalent of a single valve-based amplifier? That way, you get the same output power, but you never need to replace any burned-out tubes.
Because then the circuit would be much more complex (the need for matching all the small transmitters so they all work well in parallel) and a failed transistor could result in a lot of failed transistors. Tube circuits are simpler and tubes can tolerate overloads better.
Oh, and another thing. HVDC substations replaced their mercury valve rectifiers many years ago because new silicon-based technology could do the same job, at the same power level, with much less hassle. That's a higher level of power than broadcasting.
As the result of a rectifier is DC, it is simpler to combine a lot of smaller components in parallel and they dissipate less power than a transmitter would (since the output devices have to operate in linear mode in a transmitter, while they are on or off in a rectifier)
A lot of microwaves have a vacuum tube for the display too.
(The erie blue-green ones) VFD
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They modded you funny but any musician will tell you for guitar amps you can't beat tubes. as a bassist I prefer my Trace solid state (one of the last Brit made before they got bought by Peavey) because its hard to get a truly clean tone out of a tube but frankly that is what makes them great for guitar as even a "clean" tube tone has a warm slightly compressed midrange that is just better than solid state.
Let us just all hope that Russian Sovtek factory never goes out of business or rock would be screwed. I have heard just about every kind of modeling amp out there but none of them compare to the tone of a Marshall Plexi or a Fender Bassman or Concert, hell even a mid 70s Peavey Mace tube head sounds better than the modeling amps. Sometimes the older tech is just better, that's all.
as for TFA I'd love to see something like that filter its way down to musical applications. Can you imagine a tube amp you could just throw in a rack and that would take as much abuse as a solid state? man that would be like heaven.
ACs don't waste your time replying, your posts are never seen by me.
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.
easy to do for anyone who could follow the instructions that were on the machine and quite clear. sad she had to pay money, the Radio Shack ones were free. I used to collect TV and radios that were stood by the garbage cans the night before collection day for my electronics hobby, did the "tube dance" as a kid. Yes, I did solid state (discrete and integrated) based experiments and creations too.
> At low power levels (e.g. 10kw) transistorised VHF/UHF output amplifiers are fine. Additionally, you can get a higher power output by operating multiple VHF/UHF output amplifiers in parallel - which also gives some redundancy for transmitter maintenance.
See Pentium 100's reply; he hit the high points. But it's essentially a matter of cost-effectiveness. If you tell me, "I need 30,000 watts at 100 MHz (a typical FM arrangement), I'm going to use a tube. Even after paying $5,000 for the tube and building a 10,000 volt, 5A power supply, I'd still come out ahead. Combining enough 100-200W solid-state modules to get that kind of power level would be far more expensive.
There's a practical matter, too -- for example, or 50 KW AM stations *do* use solid-state, and they're done as Pentium100 describes: you combine bunches and bunches of modules to get that power level. That's at a much lower frequency, and they can be made very efficient .. . .. but with full modulation, our Nautel transmitter runs a 300V primary supply and draws in excess of 300 amperes(!). There are giant 3/0 cables (they look like booster cables!) running all over the inside of that thing just to handle the current.
Can't cheat physics: power = voltage times current.
But I'll add this: Some competitively-priced solid state high power transmitters have begun appearing, so I have hope for the future. (We're looking at some of the new Nautel FM units ourselves; www.nautel.com if you're curious.) But seriously, even as recently as 2 years ago, there was no question that a 4CX20000 tube in a tuned cavity was far more cost-effective than trying to do it with solid-state.
Cogito, igitur comedam pizza.
Since there aren't any vacuum tubes (valves for our European brethren) being made in North America anymore, guitar amp parts suppliers source new tubes from Russia and other communist (i.e. China) or former communist states (now that Putin has installed himself as supreme soviet, is Russia still non-communist?). For example two major tube makers, Sovtech and SED Tubes are both based in Russia. Most of the North American tube makers sold their equipment to folks in these countries. The tube makers who didn't just scrapped everything. I am pretty sure even GrooveTube are made off shore in one of these countries now.
-- I ignore anonymous replies to my comments and postings.
former communist states (now that Putin has installed himself as supreme soviet, is Russia still non-communist?).
I dunno how a person can be a "supreme soviet" (soviet = council; "supreme soviet" was the name for the parliament of most communist countries). Anyway, Russia is still decidedly non-communist, since it has full-fledged private property on everything including means of production. It's an authoritarian capitalist country, much like Spain and Chile were back in the day.
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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