Schematics of my first tube amp

In older post I wrote that long time ago I built my first tube amp. Today, in old magazine, I found the schematics. As I remember, the output stage was working, but I made some mistakes in pre-amp. I left amp for very long time and my mother decided that it was junk and threw it away. 🙂

Big schematics for printing.

Recommendations for sound quality improvement: remove C9, C10 and C11. Change R2 to 240K, add feedback from output via 10K (R16) to Л1б cathode (dashed line in the circuit diagram).

Output transformer: Ш form core. Size of the core is about 4cm². Primary 2500 turns ПЭЛ 0.16 mm wire, secondary- 75 turns of ПЭЛ 0.8-0.9 mm wire. Output power ~3W, output resistance 4.5-5 Ω.

Tubes: Л1 – 6Н2П, 12AX7; Л2- 6П1П (miniature analog of 6П6С = 6V6!, maybe 6AQ5?)

Schematics from Радио 8, 1967.