Could a vacuum tube (solely for audio use) be substantially improved with different than commonly used materials or even geometries, or have these things been optimized by now?
I have read of gold-plated grids being preferable.
For the cathode, what properties besides low work function are crucial for performance? Since it’s the cathode’s surface whose work function matters, wouldn’t we want the least resistive base metal still? What makes for an optimal anode material? Would a silver or gold (plated) anode offer any meaningful benefit over a nickel one?
Could it be that the differences between standard metals used and ideal ones might not matter so much in a preamp tube but actually might in a power tube?
Also, could quasimetallic NDD (nitrogen-doped diamond w/ high N content) be used as a coating for very hot -running cathodes, as it’s extremely robust and has a 3.1 eV work function?
Lastly, the Sennheiser HE-1 got me thinking, surely they aren’t the only ones using quartz tubes for nulling microphony? It’s a great idea.