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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.
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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.
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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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").
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).
upon the advice of my lawyer, i have no sig at this time
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.
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.
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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