Ah, I misunderstood the way the ISC module works. I thought it meant you could do just one ground plane measurements and use that to 'fix' all the other polar measurements. Did not realize you had to repeat the process for every angle.
I definitely get the point about lower resolution. I cut off-axis measurements at 200hz myself, and it's not ideal. If you can get full low frequency resolution that's awesome!
But that said, when it comes to
assessment of a speaker imo there are plenty of ways to get around that particular resolution flaw for resonances. They'll usually show up in the nearfield measurements, and when I'm curious about how that looks from different angles, I find just measuring from a few inches away at a few points is enough to minimize the influence of the room and identify any major resonances. And of course there's ground plane too, So for my own purposes, presenting a spin, I'm not very concerned about the lack of resolution there.
Personally, I think having a full spin is useful. But that said, if you don't want to do the full rear measurements to save some time, you can get quite close by just selecting a few key rear angles.
If you import the curves to vituixcad, adding just the 180 degree curve to the front hemisphere one should get you a nearly identical early reflections curve with monopole speakers.
For example, here's the >200Hz spin for the Amphion Argon1 with the full 19 rear measurements. This speaker has particularly loud port output, so it's kind of a worst-case scenario monopole.
View attachment 66037And here it is with just front hemisphere + the singular 180-degree measurement:
View attachment 66038
The sound power and DI curve suffers a bit at low frequencies but the others are imo close enough. I personally don't even care about the sound power with typical speakers anyway.
But if you want that last bit of detail, if you add just the +/- 120, and +/-150 measurements the spin should be virtually identical:
View attachment 66039
So doing a few rear measurements and letting VituixCAD fill in the gaps could be a good compromise.