Since there are no measurements of the M3 or M5, we simply simulate the radiation pattern of the tweeter without crossover and analyze the result - wow, how exciting
I lack the exact dimensions (membrane height, suspension,...) of the tweeter, there may be deviations in the range above 6-8kHz. Also, I have had the software reliably calculate the simulation only up to 9kHz.
Here is the sketch of the simulation:
The virtual measurement microphone is located at the height of the tweeter axis at a distance of 2m.
All diagrams show only the tweeter response - keep that in mind!
But due to the fact that the crossover frequency to the tweeter is 570Hz, the directivity of the tweeter represents almost the entire speaker.
UPDATE: The simulation software assumes an ideally behaving tweeter. Deviations in the frequency response that the real tweeter has are not included.
Horizontal Frequency responses of the tweeter deg0-90
The speaker should probably be listened to directly on axis, because then you benefit from a frequency response drop in the range of 2.5-3.2kHz, which should provide a pleasant sound.
Horizontal normalized frequency responses of the tweeter deg0-90
As expected, the speaker shows a very good dispersion behavior below 1 kHz. The reason for this is the flat baffle, I use this effect myself in all my projects.
Since the crossover at 570Hz is done with a second order filter, the transition to the open-baffle woofer should not cause an abrupt change in directivity.
Things get a bit wilder in the frequency range 1-4kHz - also as expected. The directivity is uneven in this frequency range. Therefore, the manufacturer is probably not interested in publishing measurements.
Horizontal normalized spectrogram of the tweeter deg0-180
A lot of "sound energy" is emitted horizontally from the upper midrange to the middle high frequency range.
Vertical normalized spectrogram of the tweeter deg0-180 (the lower half of the diagram shows the directivity upwards over the tweeter axis.)
Due to the low crossover frequency of the tweeter, the vertical dispersion of the speaker is exceptionally good.
Early reflections (expected in room response) for a linear on-axis frequency response
The conditions for very good behavior in the listening room are given.
Please do not be put off by the hump in the 2-3 kHz range, as we saw above with the simulated frequency responses, there is a dip on axis in this range.
This means that this hump should not be so pronounced in the real loudspeaker (as long as the axial frequency response will not be linearized).
A really very interesting concept that also works out quite well.
The speaker's power handling should be within limits due to the very low crossed tweeter.
It is difficult to predict how the radiation problems in the frequency range 1-4kHz will play out in reality.
But maybe
@amirm will get a M3 or M5 to measure.