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pertinence of Valve Amplifiers

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vinodquilon

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Recently I have read Morgan Jones' Valve Amplifiers.

Does there exist any relevance for Valve Amplifiers in these days of semiconductors ?
 

fcfusion

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That an old discussion between old school and modern electronics engineers.

When it comes to audio apllications, old school guys defend the valves provide a warmer sound. However transistors can be much smaller, cheaper, generate less heat and provide better linearity.

IMAO there is nothing a valve can that a million transistors on a chip can't. If you want a warmer sound you can always do it digitally :D

when it comes to Very High Power transmission (RF communications) valves can handle much more power than transistors. In these situations, valves are still the only option available. Valves are usually used in broadcast systems.

Hope it helped
 

    vinodquilon

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pauloynski

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Not to mention that valves do not melt as fast as transistors, a very apreciated advantage when you shortcut the output of your amp. :D
 

fcfusion

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pauloynski said:
Not to mention that valves do not melt as fast as transistors, a very apreciated advantage when you shortcut the output of your amp. :D

Yeah right. Any decent transistor amplifier as short circuit protection. That's not a very good argument. Besides that valves filaments can blow up, the gas inside deteriorates, etc. Valves have a lot of reliability issues.

Valves are history man. Transistors for the win.
 

jgruszynski

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In terms of reliability: valves/tubes typically have life times in a 0-10 year range even operating at room temperature.

Semiconductors can have lifetimes from 10-10,000 years depending on the geometry (generally larger last longer, smaller not so much) and operating environment.

If you've worked with tubes you'll know the experience of having to test every brand new tube out of the manufacturer's box and having out-of-box failures as high as 3 failed for 1 working.

Imagine the fun I had working on Nike Hercules tube-based servo drivers which had several dozen tubes to implement tube-based op amps and amplifiers. I'd go through several containers of 50 tube boxes just to get a system back online. And doing this in the Mojave desert at 120F/49C made this a regular task I don't miss.

All that said, there are certain applications like high power microwave amplification that can only be done with tubes (typically magnetrons, klystrons, TWTs, BWAs, etc.). Pretty all communication satellites still use TWTs to relay signals.
 

mabdinur

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Valves have their place in high voltage applications, and are a lot more resistant to EMP. I would assume Radio, Radar, Microwaves, Surgical Diathermy, and Acoustics still have uses for Valves. Hey I have that Morgan Jones book as well, a great read in the way it is written haven't finished it yet but I still can see why certain knowledge of this can be relevant.
 

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