Here is another built of my favorite 01A DHT,  Thoriated Tungsten filament.

It uses the Lundahl LL2745 in a 5.6:1 step down configuration. A separate enclosure power supply is providing low ripple high and low voltage. A 7 wire umbilical cord brings the power to the main preamp chassis. This preamp is solid state assisted on both high voltage and low voltage side. The 01A is filament biased using Coleman regulators.

There is no capacitor in the signal path besides the power supply ones. There are minimal parts in the signal path carefully chosen for reliability and sound quality.

01A is a superb sounding tube and can often improve the listening experience when combined with solid state amplifiers, digital recordings. There are still plenty of 01As available outthere. Just be patient to find the less microphonic ones. As usual, I dealt with reducing the effect of microphony by starving filaments and suspending the sockets on neoprene mounting dampers.