This idea seems kind of abandoned. Raytheon tube is cheap, and some documentation is available.
There is this Naiant MSH-4 mic:
https://naiant.com/microphone-design/
And Audio Technica patent files:
https://patents.google.com/patent/US20050254671?oq=akino+microphone+0254671
I don't know if it's legaly ok to explore further this patent, but it would be great to be able to make mics based on it. The values of components are absent obviously in the schem.
AT is great as it uses less current, but needs a transformer.
Maybe make a version with regular LDC capsule.
There is this Naiant MSH-4 mic:
https://naiant.com/microphone-design/
And Audio Technica patent files:
https://patents.google.com/patent/US20050254671?oq=akino+microphone+0254671
I don't know if it's legaly ok to explore further this patent, but it would be great to be able to make mics based on it. The values of components are absent obviously in the schem.
AT is great as it uses less current, but needs a transformer.
Maybe make a version with regular LDC capsule.