Back to microphones - but please carry on these interesting discussions.
I asked for advice on another forum (French) which has some contributors with a lot of experience of microphones/recordings, because I was not terribly happy with my recordings - frequency response, and noise floor.
One person has the same recorder (Tascam) and same microphones (Superlux S502) as me, and has made measurements. He found that the "advertised" frequency response is far from what you actually obtain, and applied the following equalisation curve to his recordings in order to get a similar sound to what he heard in-room:
View attachment 111472
Those are pretty significant filters. It is not night and day, there are more significant differences between different speakers, but it can make a recording sound a little less bright and with more low end.
In comparison, I uploaded into Audacity an equalization curve corresponding exactly to the calibration file of my Umik measurement microphone, and it looks like this:
View attachment 111473
So as you move from an in-build microphone to a budget external microphone you probably improve the resolution obtained, there is no guarantee that the frequency response is really that much improved.
The filters that Ron applied enabled him also to get a sound closer to what he heard in his room.
In mid-frequencies, the response is flat, so that is fine to detect colorations of speakers in that range, but in the bass and highs the picture you get from a recording is not very accurate!