Tube amplifier WR75
- Category: Gallery
- Published: Tuesday, 09 January 2018 09:59
- Written by Grzegorz Makarewicz
- Hits: 2272
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.