Tube Amplifier "Прибой" / Priboi.
Resurrection of old russian tube amp.

Parameters after modifications:
Output power: 2x 20W sin / 4 Ohm, Class A
Power consumption: 200W
Used tubes: 6Н3П, 6Н6П, ГУ-50 (used as triode)
Volume pot-meter: Alps
Feedback: utilizes combination of Voltage Negative Feedback and Current Positive Feedback.
A hint of Positive Feedback helps to control hard-to-drive multi-band speakers. ГУ-50 tubes are widely available and therefore is no more problem with getting spare tubes.

Wiring diagram, original
Wiring diagram, after modifications
User/service manual