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Month: October 2020


Figaro Tube Line Preamplifier

The beating heart of this project is the 12B4-A. This 5.5 W single indirectly heated triode an amplification factor μ of only 6.5, coupled with a plate resistance of a only 1kΩ , is the ideal candidate for a great linestage. Due to low μ I opted for a plate CCS ( Constant Current Source ) A CCS presents an ‘infinte’ AC load to the tube, maximizing gain. This high resistance load to the plate,…