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 think a compactron is a multiple tube in one envelope, but I'm not sure. I've never heard a double triode or a triode-pentode or a triode-hexode or a double-diode-triode called a compactron. Anyone able to shed some light?