h a l f b a k e r yAssume a hemispherical cow.
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I'll start by pointing out that
valve is a British term for
vacuum tube, and that that we
couldn't call small tubes nanotubes
because that term is already in use.
(I think nanotubes are very long
threads of fullerene or something.)
Actually, this isn't so much a
proposal as wondering
if it would
work and if it would offer any
advantages.
I know that people go to extra
trouble and pay extra money for
audio devices with vacuum tubes,
particularly home audio amplifiers
and guitar amplifiers.
It also seems to me that the
technology for making really small
things has improved since the point
in time when conventional wisdom
decided that vacuum tubes were
passe and transistors, later
integrated circuits, later chips, were
the way.
So, could our current technology
produce, say, a vacuum-tube iPod?
And would we want to? Are there
audio purists who don't like "the
transistor sound" who'd like a
personal audio player with tubes?
I'm just guessing, but I'd think a
small enough tube (1) wouldn't
require too much power to make
this
feasible, (2) wouldn't get too hot to
be used, and (3) wouldn't take the
20-30 seconds to warm up that my
old table-top radio with inch-and-
a-
half long tubes used to take. Or am
I
wrong? Would a tube iPod
necessarily
drain four AA's in a half-hour and
get
hot enough to burn its way out of a
shirt pocket? And am I wrong about
the possibility of manufacturing
vacuum tubes the size of a Tic-Tac
(or smaller)?
What does anyone think?
PDF FILE: A Micromachined Vacuum Triode Using a Carbon Nanotube Cold Cathode
http://repositories...&context=postprints
"fully integrated on-chip vacuum microtriode using carbon nanotubes as field emitters" [half, Jan 05 2006]
Nanotube radio
http://www.physics....anoradio/radio.html
[jutta, Jul 14 2008]
[link]
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Great idea, I'm afraid I don't know the answer - [angel] will probably know as he's quite valvey. My only concern is that during the period they were making valves they also made flashlight bulbs which were around 10% of the size of the valves. If they could make filaments and glassware that size, wouldn't they have shrunk the valves if they could? Just a thought. |
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Thanks for finding the
"Micromachined Vacuum Triode"
document. The other part of my
question is would anyone buy a
"tube iPod?" |
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'Are there audio purists who don't like "the transistor sound" who'd like a personal audio player with tubes?' |
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The answer to the first part of that question is yes, so the answer to the second part is probably the same. (If the NanoValves produced the same purist pleasing harmonics/distortion/warmth as produced by an ordinary vacuum tube) |
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//would anyone buy a "tube iPod?"// Yes. Definitely. Even if it sounded exactly the same as a transistor iPod. |
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The even harmonics produced by a traditional glass-envelope vacuum tube, such as the American 12AX7 dual triode, don't seem to be quite as present in ceramic-envelope tubes. I haven't heard a good explanation for this, and I'm not sure you'd get the same effects with what amounts to a carbon envelope. |
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Also, there's the concern of
miniaturizing tubes down to the scale of modern transistors or smaller - at that scale, I'd think a thermionic device would behave so much like its semiconductor counterparts as to sound like the same thing. |
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The equipment wouldn't necessarily have to be hot or power-draining, as you can easily make a cathode with a coating of thorium and eliminate the need for filaments altogether. |
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They've made some pretty small tubes in the past. I have a Victoreen radiological survey meter, Cold-war vintage, with a very small electrometer tube inside, good for 100+ hours of operation on a single D cell battery. |
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+ for the idea of a tube iPod. I'd buy one, assuming I could even afford the plain vanilla semiconductor version. |
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In my teenage garage-band days, I got to play with some nice tube amplifiers. Sweet noise. |
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A tube ipod would double as a pocket handwarmer. Might need BIG batteries as tubes take a LOT of current!!! |
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They make your hi-fi glow in the dark |
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//Remind me, what are the real and desirable advantages of using valves in audio?//
Crank a Les Paul up with a Marshall valve amp and check out the broken distortion!. Much nicer! |
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//what are the real and desirable advantages of using valves in audio?// It's to do with the electric, it needs more room to move about in the wires, and valves probably provide both that, and a warming heat source by which a sepia tinted 1940's family can cower around while they listen to the soothing, sonorous voice of the Home Service telling them that everything is all right. |
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In addition, valves are more likely to remain viable after the emp blast of a nuclear weapon, so if you want to listen to the radio or your iTunes after the apocalypse, valve technology really is for you. |
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Hmmm. Suddenly you don't seem so new and hip anymore. |
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"Remind me, what are the real and desirable advantages of using valves in audio?"
Purists perfer the sound - however I think that's when you're dealing with an analog source (record/tape). I don't think there'd be any improvement using MP3s. And the whole kit would get very warm. |
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