When I wuz at school, we had us a science teacher who was into ham radio like a rat up a drainpipe. We got chapter and verse on radio/electrical/electronic terminology, including pots and the derivation of volume, plus more about valves (tubes to you USns) than I ever wanted to know, even when I was wiring them up for real in my first home-made amp, which was a doozy, 200 watts RMS.

It went, as Nigel Tufnell would say, up to eleven. I had to abandon it (sob) when the valves I was using became unavailable. Funny thing is that now, some thirty years later, they are making the damned things again!