Tube amplifier WR75


Written by "Dziadek" This email address is being protected from spambots. You need JavaScript enabled to view it.

It is now fully functional copy, unfortunately without the original parts. As you can see, power amplifier uses:

  • the beautiful 6P3S tubes at output stage,
  • the 6N8 as a phase inverter,
  • the EF183 as microphone preamplifier and
  • EF80 as gramophone preamplifier.

As the result of long-term "residence" in the wet room, all the paper capacitors were "dead", and so the most of the resistors.



Fig. 1. Power supply choke


Fig. 2. Beautiful view of vacuum tubes


Fig. 3. Power transformer (probably has 500VA) and output transformer


Fig. 4. And here, smoothing filter capacitors


Fig. 5.Another shot of power transformer


Fig. 6. Output transformer, and a nice red rectifier in the foreground. A rectifier (selenium of course) provides bias voltage (at the top you can see the plug to change the voltage range of the output transformer and on the right bakelite "PCB" for EM4 magic eye) 


Fig. 7. Power socket and the socket for connecting a volt-ammeter


Fig. 8. Speaker terminals and fuses: mains (left) and anode


Fig. 9. Nameplate with trademark, name serial number and production date


Fig. 10. General view of the amplifier


Fig. 11. In the evening during sound reproduction


Fig. 12. And the impressive  magic eye (a pity that only one)


Fig. 13-15. It's high time for the "whole"

Amplifier, due to construction (beam tetrodes) is characterized by an incredibly warm sound and power, which certainly exceeds 100W. Original input sockets were a banana type but I changed it to a "JACK" type for obvious reasons (amplifier serves as an instrumentation device). At the bottom there is a microphone and at the top a gramophone socket.

Sincerely, "Dziadek" This email address is being protected from spambots. You need JavaScript enabled to view it.