Double bass array. Low Q subs. [Quasi]plain wave radiation?

[Flaesh]

Where is your crossover set to the subs

IIRC a little lower 90 Hz. Speakers delayed up to smooth PET.

ringing is the same?

Not completely. Initial decay improved, while tuning is unperfect, while decay before wasn't very bad. IMO\IME improving initial decay is audible in general case, while tails, say below 20 dB, [may] remains in real world.
It is also obvious that the delay is excessive in the old picture.

 

[Flaesh]

Room may be called untreated. A little bit of polyester is lying around.

 

[Flaesh]

I'll quote myself from another thread (so that I don't have to search and\or write again in the future), in response to the question "how to build a [budget] subwoofer with an external amplifier [and processing] and achieve good results":
I hope you already have external processing capabilities, right?
Then you only need a power amp. Any decent power amp with enough power for the drivers and enclosures you're using will do.
The driver(s) can be any decent driver(s) with sufficient displacement in the enclosures used, provided they can handle the power applied. For example, the JBL 2269H is better than a no-name car subwoofer costing $40; but the former is more expensive.
The enclosure, of course , can be any decent one. A sufficiently sturdy box would be better. The criteria for enclosure volume include the room design, the parameters of the driver used, and the permissible power when using equalization.
Take into account the room's transfer function (RTF). In general case RTF for any\every placement of the transducer and listener\mic can be easily estimated by using virtually any driver in a sealed enclosure and comparing the in-room measurement with the anechoic frequency response of that driver in that enclosure.

RTF can vary significantly in different rooms and locations; therefore, in general case the simplest and most reliable method is to measure it. Instead of dreaming about a 12 dB/octave room gain.