Tube Mosfet Hybrid Headphone Amplifier Circuit

The sound quality is pretty good I guess. The lamp used is 12AU7 Mosfet irf612 circuit, not too complicated. The supply is 12volt dc. As a follower of several YAHA amps based on the Fa-schmidt design and a Szekeres Mosfet, I wondered how the two would sound together.

So I installed the schematic in TINA-TI, a free program for testing circuits before construction, and the results were remarkable. Approx 20dB gain from 13VDC power supply from 20Hz-100kHz.

As you can see in the diagram, there are less than 30 individual components and most DIYers will get them as spares from other builds.

I chose the 12AU7 / ECC82 vacuum tube because it can be operated with low voltage and the filament voltage is 12.6 volts, so there is no need to regulate the voltage further. I used a 1/4W resistor in the first stage and a 2W resistor in the second stage.

2W resistors may be too much, but I didn’t want to change them later. The 20ohm resistor should be a minimum of 5W and do not use cable wrap as the inductive properties will distort the response curve.

source diyaudioprojects.com