This is a Single Ended 45 Amplifier I built. It used TubeLab power supply circuit board. It can use 2.5 and 5 volt filament tubes so the amp can use also use 183, 2A3, and 300B tubes. It has Tomiko OPT-300B torroid 5K output transformers. Input tubes are 5842WA. A GZ34 rectifier. Sounds great.