Compact nearfield WAW?

[Scarface1]

That makes sense about the PR becoming part of the structure (assuming screws make the joint completely rigid), and adding a ring of material under the flush-mounted basket of the PR would further stiffen things.

I'm still considering adding PRs, but as I'm currently getting response down to 30Hz in-room, it seems difficult to find PRs that would extend the response low enough. A single PTT4.0PR seems like the only choice, but for similar cost I could just get another Sub120 and have proper force-canceling etc.

Not sure what you mean with the ply edge. I've only lazily painted the enclosures dark grey while working on a 3D printed enclosure (pic). I also wanna try a smaller BMR driver instead of the NE65W - just to make things slightly more compact 🙂

View attachment 1253989

Hi Jaakkopetteri, i have a sub120 at home and have thought about some things to make it play to 40hz but can't find a solution! The only passive radiator i come across is the Dayton dma 105 pr ( if i'm correct ). With 2 of them in a 2 liter enclosure and Max added weight i can tune it to 60hz flat response! With dsp you can set a high pass filter at 60 hz so that everything below 60 hz get as much xmax as possible but not exceeding it. In my head it's like, it's not tuned at 40hz so why even do it BUT you get almost the same out in your room at 30hz but with the passives boosting the upper sub bass.
With a bit of luck you get a very flat response because roomgain will occur at half the wavelength. At 3,4 meters you have a +3db starting point ( roomgain ) at 50 hz. At 30hz you have maybe +10db. The excursion of those passives are 9mm with the same surface erea of the kartesian sub120. Because of the smaller rubber surround they are only 105 mm. My idee was placing them above the kartesian magnet on both sides( left and right ). The added weight should be untouched by the magnet force because it's a few cm above it.

 

[Scarface1]

Another passive radiator with even less installing depth. Already knew this PR but didn't like the aluminum color cone but they have black paper cone to

 

[jaakkopetteri]

Yeah I've modeled pretty much every 4" PR there is and relative to 100Hz, the max SPL at 40Hz is already down by 10dB or so in the ~2liters I have available, even with max added weight. Max SPL for some setups:
Blue: 2xSub120
Thin yellow: single PTT4PR
Bold yellow: SB12PFCR-00
Green: Vented Sub120 tuned to 35Hz (not a fair comparison as vent volume is not accounted for)