So, there is trouble below the transition frequency. In a high powered speaker like that with a lot of power below 600 Hz, there will be room dependent problems.
Eq, very likely will help this.
However, I think Perlisten made a huge error of judgement not to make this speaker active, at least partially. When you design and build a potent speaker like that, it is going to be very room/position sensitive. If it were active, then the output below transition could have been made easily variable. That is why my front three have continuously variable baffle step compensation. My rears allow considerable trimming of BSC, and the surrounds have two choices of where the transition starts. These are the smallest of the seven main speakers, not including the ceiling speakers.
The active control settings of the front three speakers and the rear backs, are very different between my old room in Benedict and the one here in Eagan. The design made transferring the speakers between the two locations a simple endeavor under instrument control.
The other issue is the Perlistens are still a resonant design. In a speaker with prodigious power in the last two octaves having non resonant aperiodic bass alignment is a huge advantage. Unfortunately since the death of John Wright of TDL, less people have had the opportunity to experience it than heretofore.
I started design work on my front three early 2000s, after George Augspurger published his TL model. Modelling software created by George can be downloaded from
my website and is available to all. Quite a few DIYers have now downloaded it. It really is a pity no one has used this model to offer commercial offerings.
I think in a state of the art speaker, the deign should now be fully active. I did not make my high pass crossover to the tweeters active, because at that time I could not justify power amps to drive tweeters. However, if I were designing it now, with what is available I would have done an entirely active design.
The other issue I have with Perlisten's design is having crossovers right in the most sensitive part of the speech discrimination band. Don't get me wrong, the crossovers are very good, but not perfect, as there is no perfect solution. You can see the imperfections in the data you published. Unfortunately experience has taught me that the ear is just devilishly sensitive to phase and level aberrations in this region. I have a personal rule of no crossovers from 800 Hz to 2.5 KHz, and if possible, not between 500 Hz and 4 KHz. Unfortunately that really restricts your selection of eligible drivers.