Diyaudioprojects feature a DIY tube-mosfet hybrid headphone amplifier. It uses 12AU7 tubes and the IRF510 mosfet. The schematics, and pcb files are available on their site. The circuit consists of two stages: 1. a common cathode tube volt amp stage (gain), 2. a MOSFET source follower for current gain (with a LM317 regulator used as […]