Gu-50 in Triode Mode substituted for a 300b in this SE Schematic : r/diytubes
Gegentakt-Verstärker in AB-Betrieb fuer GU 50
Röhren-Verstärker mit der LS 50 (GU 50)
GU50 (FU50) with 6SJ7 amplifier - some help | diyAudio
Weiliang Audio Gu50 Ry50 Tube Amplifier Single Ended Class A Valve Amplifier 8w Stereo Amplifier Bluetooth In Sound Alike 300b - Home Theater Amplifiers - AliExpress
GU50 single end
SE GU50 tube build - Talkin' Tubes - The Klipsch Audio Community