Class A.<p>Possible to use less-expensive tubes if that's all you've got.<p>Part 1, 2:28 - finished amp, it's stereo.<p>Part 1, 13:00 - audio schematic, one channel only.<p>Part 5b, 3:55 - hand-wired power supply. No circuit board needed.<p>Part 8, 10:49 - final hand-wired circuit. No circuit board needed.