I've got another thread about testing microphones.
I bought a cheap Behringer reference microphone and it seems to work pretty well using it with REW to get a reference trace from my cheap Thomann powered speaker (EQ set flat, 4 10 second frequency sweeps at 0.5m in a large room with plenty of soft furnishings and curtains closed).
I asked a query there which has gone unanswered that I wonder of the likes of @stevie or @Phil Starr can answer.
REW also produces phase plots, and the one for the speaker is below. It shows several phase reversals, mostly well beyond hearing range.
One just above 100hz probably relates to the reflex port and is to be expected.
Another is just below 2kHz and is accompanied by a dip in the SPL trace.
My question is: Does this make it likely my tweeter is wired back to front, and could reversing the wiring help eliminate the dip?
Any other observations welcome (yes I know this is not a very flat trace at all, although it sounds fine and works well as a monitor).