• 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.


Alex, I've built a couple of "mulligans" as RH connected EL84s, my favorite currently being parafeed output monoblocks with EF86 drivers.

As much as it definitely is a huge improvement over the triode strapped circuit, I'm interested in trying the same upgrade to an EL34. The allure of more power beckons.......

The schematic published on DIYAUDIO.8m for LAF SE34RH shows several differences from the EL84 (aside from the obvious differences in operating voltages).

My main question is what is the value of Rfb that is missing from the drawing?

I'll probably build at least 2 of these, one with ECC83 / 7025, and the second with EF86 per channel.