My brother and I have build two 6C33 SET (single ended triode) 15 Watt Class A amplifier. This is a very nice amplifier with a very pleasant warm soft sound and you don't get tired listening to the amplifier and ee are very pleased with the finished result.
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Underside of the PIC control board, reinforced with extra copper wire to withstand approx. 15 Ampere (6C33 filament and idle current approx. 2x200mA @ 210V)