Subwoofer with backwards and forwards driven 12 inch infinity kappa 9 woofers. Heavy coned 12 inch mounted bottom fire. Port stuffed well. Driven woofs fire opposed. So, the combined pneumatic action excites the for all intents and purposes, passive radiator. Plate amp has phase and variable crossover point. To my ears, it is tight, and well tamed. it has dipolelike dispersion. Good output and doesn't seem to honk. With the phase knob, I THINK I can coincide the bottom with the forward and rearward driven woofs, or at least, get them somewhat in phase with the mains. My mains have 8 inch woofs. So, the crossover point is lowish.
Reason I ask, is cuz I have read that passive radiators are supposed to be twice or so, the size of driven ones. But, with 18db cross, and variable point, along with volume to boot, I FEELLLLLLLLL that it is quality bass response.
Am I just playing cebo? Hearing what I WANT to hear? Or are there enough adjustments to tame the response to somewhat flat?
Reason I ask, is cuz I have read that passive radiators are supposed to be twice or so, the size of driven ones. But, with 18db cross, and variable point, along with volume to boot, I FEELLLLLLLLL that it is quality bass response.
Am I just playing cebo? Hearing what I WANT to hear? Or are there enough adjustments to tame the response to somewhat flat?
Great to hear you like your subwoofer 
Do you have pictures of it?
Some comments, do not let them discourage you:
If I understand correctly you have a subwoofer with two driven woofers and one passive radiator. Passive radiators cannot be mounted down or upfiring, as they eventually will sag downwards. Passive radiators are recommended to be larger than the driven woofers because they will run out of excursion before the driven woofers, so that would limit maximum output. Dispersion cannot be dipole like, it is dictated by physics to be monopole. The response could still be flat however. Not that directivty matters too much, bass directivity is not possible in a typical size room. The directivity (at bass frequencies) only plays a role in what room modes are excited. The room modes usually mess up the response, which you can counter with a parametric equalizer. Horn honk is typically located in midrange frequencies, not in bass.
Do you have pictures of it?Some comments, do not let them discourage you:
If I understand correctly you have a subwoofer with two driven woofers and one passive radiator. Passive radiators cannot be mounted down or upfiring, as they eventually will sag downwards. Passive radiators are recommended to be larger than the driven woofers because they will run out of excursion before the driven woofers, so that would limit maximum output. Dispersion cannot be dipole like, it is dictated by physics to be monopole. The response could still be flat however. Not that directivty matters too much, bass directivity is not possible in a typical size room. The directivity (at bass frequencies) only plays a role in what room modes are excited. The room modes usually mess up the response, which you can counter with a parametric equalizer. Horn honk is typically located in midrange frequencies, not in bass.
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