It's all here...
taste_of_tubes.pdf (ken-gilbert.com)
Best understood with some electronics 101 reading.
Can anyone explain what a power tube does inside an amplifier, eg kt88.
I know a tube is cool looking, and looks like a small lightbulb with many pins on one side and when it's turned on filaments glow inside a vacuum enclosed see-through curvy glass enclosure. I guess current flows in, goes on a journey, and then flows out.
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@emergingsoul Someone mentioned using CHTgpt, so I decided to access it and a pretty good and simple explanation comes out. Here is what it says: Today
Default (GPT-3.5)
 provide a simple explanation of how an electronic tube, such as a KT-88 amplifies a signal
ChatGPT
An electronic tube, like the KT-88, amplifies a signal by using a process called electron flow control. Here's a simple explanation of how it works:
In summary, an electronic tube like the KT-88 amplifies a signal by using controlled electron flow. The input signal applied to the grid modulates the flow of electrons between the cathode and anode, resulting in an amplified output signal that reproduces the input signal but at a higher level of strength. This process is used in vacuum tube amplifiers to boost the power of audio signals for applications like music amplification. Free Research Preview. ChatGPT may produce inaccurate information about people, places, or facts. ChatGPT August 3 Version
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I have often wondered this. The tube makes a larger copy of a signal, yes. But how? I imagine they are called valves because they act as gates, only opening to release the larger copy when it is large enough based on specs. Again, how? How does it increase the size and know when it has accomplished its goal? How does the gate open?
I can understand and explain how a gas engine does what it does, but not a tube. Ive read some technical explanations but they always seem to avoid the actual answer to the actual question.
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Chat GBT did a great job above. And your comment asking how it actually controls the valve activity is very key. Also there was a document above from @tablejockey that looks very promising. Ultimately the end answer, is likely very simple, amidst all the complicated fog. When you ask a child, even in adult, how something works, like how things work when you turn on a sink faucet you'll get a good answer. But if you start going into the actual inner workings of a faucet, the child quickly gets very frustrated. Human nature is a challenge. |
It is a valve that opens and closes in response to the input signal fed to it. Output side, (anode or plate), is connected to a high voltage power supply, that feeds the output transformer connected to your speaker through the tube. The input side, (grid), accepts the tiny input signal from your preamplifier, and turns the large power supply on and off in response to that input. The result is a much larger signal being applied to your speaker , than the tiny input signal being applied to the grid. Basically how amplification of the tiny input signal is achieved. Of course there are more parts to the tube that sets the amount of current bias is applied. But the above is a simple as I can attempt to explain it. |
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