The SE Electronics Gemini II Dual Tube condenser microphone is exactly that - two vacuum tubes in a large diaphragm transformerless condenser microphone.
The unique metal screen not simply perforated but louvered at a slight angle to redirect ultra-low frequency breath blasts and to the side of the screen. This process does not attenuate high frequencies--as do fabric screens--and leaves the vocal performance unaffected, and without annoying low frequency "pops".