How does the Crack work?

[ChetJettison]

Hello all!
I've just had the absolute pleasure of assembling a Crack. It is working great and it sounds marvelous paired with a Khadas Tone Board and the HD650s I got specifically to go with it.
It was a joy to make. But the entire time I was putting it together, I was wondering... How is what I'm doing going to result in sound? I know... it's an AMP. But really... what IS an amp? What is the THEORY behind the operation of this device? HOW is it performing the function of amplification?
And specifically, what do the TUBES do?
I know very little about electronics and circuit theory, so in many ways the Crack is for me a BLACK BOX... I know that signal goes in, and amplified sound comes out... but I don't know HOW. Are there any explanations for how this thing works? Anything to help me understand the science behind this device? Anybody want to take a CRACK at explaining it to me?

[bernieclub]

Before getting into the heavy lifting, you might want to just google the question.  There are many simplified explanations online.   Good luck, and have fun!

[Paul Birkeland]

I would start with the NEETS training manual, or the physics series at your local community college.  You can build enough knowledge from physics 101 to comprehend what resistors and capacitors do, then discussing how a tube works isn't as nebulous.

[oguinn]

Uncle Doug is a good resource for beginners. His videos are about guitar amplifiers but many of the principles are transferable to hifi.