• 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.

6N17B Phono

I just stumbled across the 6N17B pencil tube and it looks intriguing as a phono preamp input tube as it has fairly high mu and reasonable input capacitance. I suspect that it might also be fairly free of microphonics.

I suppose that these types of tubes might be inconvenient having no base but I suppose perf board could be used. Pencils could be a very interesting subspecies to play with.