I'll try to be as concise and keep it as simple as possible.
Yes. Total harmonic distortion and it's profile, noise, frequency response, phase.
Natural resonance of any component within a mic will cause some amount of ringing (resonance) and interfere with several elements of the sound.
Overismplified, same as first answer + pattern characteristics, proximity effect, plosive control, and how a mic renders 3d sound into a simple 1d signal. In case of multipattern, how good it is at doing this without creating various side-effects.
Consistency, design, flexibility, endurance, cleanliness, stability, material, sputtering, longevity, if a technician really knows what they are doing or if it's a cookie cutter stuff (not necessarily bad) +++
You mean capsule? Yes, unless the FR deviation is caused by resonance, that can't be fixed with an eq. And this is only for FR, you can't adress other parameters with an EQ.
Mostly low end, there's a simple equation for this.
Capsule construction, many books, patents written on the topic, way beyond anyone's abilities to explain in a post. And circuit EQ correction.
This has been adressed by many in previous thread. Most assumptions here are wrong. Yes you can have LDC with better TR than SDC. It depends on frequency response extension.
AT2020 is a SDC microphone, not produced by Audio Technica, it is outsourced.
With u87 you pay for German wages, QC, legacy, consistency, reliability, high quality materials, engineers who know exactly what they are doing, tuning, future research and development, the fact it could be a main mic in any proffessiinal studio on the planet. No, there isn't 3900$ difference in sound, they are different microphones, can't be compared. I suggested good inexpensive mics in the previous thread. Surely there has to be source where 2020 will win over u87, horses for causes. 2020 has better transient response for sure, and probably lower THD, especially at LF.
AKG people don't really care about their products anymore because it's been just a brand name for a while now. Owned by companies who are in just for the profit.
Se electronics is not a reputable brand, they have no idea what they are doing which they have proven over, and over again. AT2020 explained, Rode NT1a is a perfectly fine mic, anyone having issues with this mic needs some production experience. They skimped on the headbasket to make it easier to produce, so it can be a bit improved by something like Michael Jolly headbasket mod. But it won't make a huge difference.
Microphone capsule with non reflective, non resonant headbasket. They are really one and the same. Part of the capsule system. Beyond that you just need a decent circuit of choice in order not to mess up the sound. If a capsule is designed to be EQ corrected like u87, or MKH800 you need to make sure this correction happens somewhere along the way.
There is much more to it, people devote their whole lives to just one of these components, but this is it in a nutshell.
