I’m about to get a little technical about tubes here but bear with me.
The vacuum tube is, without question, an ancient electrical component. RCA sold the first tubes commercially back in 1920, almost 100 years ago! That being said, the vacuum tube is still the standard when it comes to building guitar amplifiers. As DR. Z said in the video in the previous post, tubes have a warmth that solid state can’t match.
So they go in guitar amps and make them sound good but what do they do actually do? Surfing around Youtube I found this video that tries to explain how a vacuum tube works. It begins with an explanation of how a diode works and then moves on to explain the triode. Triodes are very common in guitar amps, mostly in the preamp but also used in the output section of some amps such as the Vox Lil’ Night Train.
What makes this video stand out to me is that he uses a water analogy. He compares the function of a vacuum tube with the function of a hydraulic system and I think it really helps to explain how a tube works and what the different components of a tube do.
I don’t think you need a technical background to understand what he is explaining. I think he gives just the right amount of information without it being overwhelming or not explaining something clearly.