Thanks for the clarification, Kai. I have two scenarios prompting this query. I have a Peluso VTB that I had done some modifications to, including removing the inner fine mesh in the head basket. Although I liked the sonic effect, it ultimately developed an intermittent low level hum that eventually became constant. Curious about the intermittent aspect of this, I checked all relevant connections to ground and experimented with mic position. The only thing that seems to effect it is placing a screen on the back of the head basket. Interestingly, placing it on the front has little to no effect, regardless of mic position. I have resorted to replacing the fine mesh screen back into the rear of the head basket.
The other scenario was a Sony C37P that I thought might be "improved" for my purposes by replacing the head basket with something less opaque.
In any case, you've answered my question. Thanks again...