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."

Re:Amps

[EdZ]

Most expensive, maybe, but best? Not if your goal is a transparent amplifier: one that takes an input, and reproduces that output as accurately as possible with a higher amplitude. Valves suck at this. An entire branch of mathematics (control theory) was developed to compensate for the horrendous non-linearities of vacuum tubes.

You may like the distortions produced by tube amps (or transistor amps outputting those same distortions via DSP), but don't pretend they're better at reproducing sound. They are demonstrably not.

Re:Amps

[Panoptes]

Tubes (or valves, as they were known in the UK) had one big quality advantaqe - noise level. A valve amplifer could produce dead silence: tranny amplifiers, even the best, had a faint but audible slushy hiss.

Re:Amps

[Anonymous Coward]

I find it interesting that the wikipedia page cites some marketing material by a tube amp vendor as the source for that info. I guarantee if you speak with someone who has designed high-power amplifiers with both tubes and transistors they will consistently tell you the transistors are the only way to go for accurate reproduction.

One of the biggest problems with vacuum tube designs is that it is very hard to keep impedance linearity across the 20-20khz spectrum. When you are trying to drive a speaker which has a relatively constant impedance of 4 or 8 ohms across that range, you have to design an output transformer to compensate across the audio range. That is not an easy thing to do.

Re:Soviet Russia

[Anonymous Coward]

...it was discovered that most of the electronics onboard the aircraft were built with micro-miniature vacuum tubes! The reason being ...

blahblahblah

The actual reason was that the vacuum tubes were proven technology and the Soviets didn't use "cost plus" defense contracting. Nobody involved had an economic incentive to reinvent the wheel.

Re:Soviet Russia

[fluffy99]

Sorry to be a whiny bitch, but the MiG-25 was actually designed to shoot down the XB-70 Valkyrie [wikipedia.org]. The XB-70 project may appear to be a failure in that it only produced two prototypes at enormous cost, but it achieved what it was supposed to in that the USSR spent a fortune building a fleet of interceptors to shoot it down.

And now Al Queda does the same thing to use. They employ a few guys with piloting skills and box cutters and we spend trillions trying to hunt down their boss and securing our airports against a non-threat.

Re:Soviet Russia

[careysub]

Sorry to be a whiny bitch, but the MiG-25 was actually designed to shoot down the XB-70 Valkyrie [wikipedia.org]. The XB-70 project may appear to be a failure in that it only produced two prototypes at enormous cost, but it achieved what it was supposed to in that the USSR spent a fortune building a fleet of interceptors to shoot it down.

This analysis is flawed - the threat of the XB-70 accounts only for the development of the Mig-25, not its production. The B-70 program was cancelled in 1962 but production of the Mig-25 did not begin until 1969.

It is debatable whether the money spent on the full 1100 Mig-25 production run was the best investment in air power that could have been made, but the Mig-25 has proved to be of historic importance as a reconnaissance aircraft. Overflights of Israel were pivotal moments leading up the Six Day War, India uses them regularly to monitor Pakistan in peacetime and in war. Its ability to outrun opponents has proven to be valuable in battle.