• 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.

The "Stupendous" 6P1P 4PP amplifier!

As far as I know, 6П3С is very close to 6L6G (not GT!) and 6П3С-E is very similar to 5881...search practical schematics and you will see the substitute I give are working.
The Russians also state that the 6П3С-E is the long-life version of 6П3С...in fact is very different also in sound. I made an SE amplifier once, with 6П3С and just for curiosity changed (without any other modification) the tubes with 6П3С-E...the sound was completely different, the 6П3С has a warmer sound, very easy to distinguish by ear. If I remember well, the Ua was 360V and Ra of the output trafo was 5K. Not the ideal conditions, but I could have a decent 5W in pentode mode.
 
As far as I know, 6П3С is very close to 6L6G (not GT!)

No. Very close to 6L6G (not GT!) is Chinese 6P3. There was a copy of 6L6 (not G) in USSR as well, but it was called 6Л6С.

and 6П3С-E is very similar to 5881...search practical schematics and you will see the substitute I give are working.

They were named 5881 by ebay sellers because they have similar height. It is a different tube.
 
The 6L6 family is a big one...all I can say is that, even if the russians say the only difference is the life time, 500 vs. 2500 (I also read somewhere 5000h), and beyond the physical differences, the tube sound different in SE application. Tested not read.
????? 6?3?, ??????????????, ?????????, ????, ??????, datasheet, ??????????, ?????, ??????????, ???????, ?????????
????? 6?3?-?, ??????????????, ?????????, ????, ??????, datasheet, ??????????, ?????, ??????????, ???????, ?????????
looking at the 5881 parameters, I say they can be replaced...
5881, Tube 5881; Rohre 5881 ID5916, Beam Power Tube
 
If anyone is interested, I designed the output stage into a circuit board.

Want a pair?
 

Attachments

  • PCB_Stupendous 4PP 6P1P_2021-02-10.png
    PCB_Stupendous 4PP 6P1P_2021-02-10.png
    140.1 KB · Views: 328
Yes. So you would have 152mA per side of the transformer.

This means you idle at just over 600mA@320V. The PSU should be beefy, 500VA PT for just B+, plus what power you need for the VA/PI stage.

Heaters want 12V @ 4A just for the output tubes, too.

I'm going to power this build from an ATX PSU and DC-DC boost. Otherwise, the easiest way to get B+ is an isolation transformer, bridge rectified and filtered. Since the 6P1P only needs about 15V of drive in this config, the VA/PI can run from the same B+. The above version uses a 6N6P per channel as VA/PI. I will use my 6F12P board instead.