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.
I have built this version, albeit with a different power supply, and used air-vane tuning caps in the equalisation (the only circuit I know where this can be done).
It's very quiet, transparent and musical