• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

GU-50 Amp

Hello everybody, please take a look at a prototype GU-50 amp ive built.
 

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A schematic would be nice indeed.

I get the impression that the filament of each GU50 is being fed from a 6.3 Vac tap on the power transformer, which gets rectifed by a bridge rectifier and than smoothened by an electrolytic capacitor. The GU50 needs 12.6 V for the filament. With 6.3 Vac to begin with, you will not even come close to 12.6 Vdc (more something like 8 V). Or do the black parts contain more than just a bridge rectifier? If there are indeed two 6.3 Vac taps on your power transformer, you could connect them in series to get the required 12.6 V for the GU50's
 
Apart from the spanky valve holders for the GU50's...
I guess the tube sockets depicted are the best ones that you can get these days. They surely are NOS, of Russian or Sovjet origin, and they hold the tube in one (!) certain position.


You'll have to remove that black plastic knob from the tube's top, otherwise the lid can't be closed, and take care not to lose it. Otherwise replacing a worn out tube might get somewhat tricky 😉.

Best regards!
 
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