Multiple smaller passive radiators or a single larger one or two?

This question would probably get more interest in DIYaudio.

Best,
E

Right on Brother!! Good idea. As Maxwell Smart would say, "Missed it by ...that much"

The rule is for every active driver, they (whoever they are) would like to see 2 X the passive radiators.  That rule applies especially to small enclosures, using high excursion active drivers. In other words, you'll blow the little PR (4") (I don't know the X Max of your PRs, (maximum throw) of your passives.) The more PRs you add, the more tuning you'll have to do..(add or subtract weight to tune).

A 10" HE active driver might need two passives, in a small enclosure so they (the PRs) won't max out or bottom out.

The same setup in a larger enclosure, say twice the size, probably will tune out just fine with a single HE 10 or 12" PR.

Non ported (infinite baffle) designs, play the loudest, but won't go as deep. This design is actually easy to blend, roll offs aren't as drastic.
Not a lot of crap to figure. Driver, size of the box (for tuning) that's it

Ported is tuned via port size and length. BUT more difficult to blend Mids, Mid Bass and Bass.

Trade offs on all the designs, No ports the least expensive way to go, mass PRs the most difficult to get right and the most $$$$$, parts wise.
Ported is good but better when you can tune the port.. length, size, ect
an probably the best for your app...

Rule to live by, Big Bass, Big stuff to get there.. Larger enclosures, larger drivers, heavy construction, thick walls. LOTS of deadening surface material, inside the structure...

There is another design also, that requires big boxes but is not used to much in home stereo. Loading the drivers inside. The porting is done before the active drivers and AFTER. Supper big BOOM BOOM in the Room Room.. To much, for most and VERY large heavy structures.
Horn or bass loaded structure, very popular in car audio, and the Horn Speaker crowd... I'm a big fan of too. I like um all... Just depends on the app...

So put on the Crab baw, and boil up some water bugs... go right along with the Gumbo an a few goggle eyed perch fishes...LOL
Got me hungry now....

Regards