They're youngsters compared to the Fisher 400 receiver and Knight KG-250 amplifiers I recently acquired and plan to refurbish. They use vacuum tubes (aka valves).
Before I dig into those beasties I want to practice on this old Heathkit IO-12 oscilloscope. Yeah, it uses tubes, too. It's simpler, more room to work inside, and so forth.
Part of the refurbish work involves replacing very old capacitors to avoid shorts, opens, and out-of-spec havoc.