FU-33 Vacuum Tube Amplifier 833A 833C DIY

Vacuum tube FU33 is a high-power triode, usually used in communication equipment, with the characteristics of high voltage resistance. Some data of FU33 are indeed very scary. For example, the maximum anode voltage can reach thousands of volts, the maximum anode dissipation power is about 300W, and the filament current can reach 10A, which is very harsh on power supply. It seems that using FU33 to make power amplifiers is not an easy thing, but why use it? A senior audiophile said, “This vacuum tube has good pressure resistance, good sound, strong three-dimensional sound field, strong dynamic output of Class A, and freely retractable.“ The DIY project spent a lots of efforts from at least 6 months ago, and now finally finished.