Any chance you could measure frequency response of the circuit, and the microphone itself acoustically? At least circuit response.
It is pretty straightforward process, revealing, and might tell you if there is anything wrong with the mic. It also helps with abstract adjectives, and might show you if different random capacitors do anything for the sound.
No, the first is the white noise signal frequency diagram , the second is the same white noise played by monitors Yamaha HS8 and recorded by microphone.
You can inject the same noise signal into the tube. Set output level to about -12db if your noise level is normalized to digital 0db. Then you compare it to the first image, you will notice if there is anything wrong with the circuit FR wise.
Or you can do the same thing with REW software and sine sweep which will give you frequency response, phase shift, distortion figure for each and every harmonic of your mic's circuit. Or measure different capacitors/tubes/transformers/bias points.
This will help you put the finger on the different aspects of the mic circuit that might bother you. Or just find out if the mic is working within specs.
