Speaker fq range, bass, low bass, low mids, mids.upper mids etc

The ther day while looking over Troel Gravesen's super high tech speaker designs,. I came across on one of his designs, a  descript of how he breaks down the fq ranges, and how he addresses edach range in that particular design. 
I just looked and can not find where he made these fq band width segmentaion.
If anyone can find it on Troels pages, plaese post the link
Or else if you know of a link taht shows how each fq range  can be generally divided up, please , be kind enough to post the link

Anyway, while searching for such a  fq band width description, I came across this article. 
Not saying I have read it carefully, but skimming over the article , lets me know this science is way out my range of understanding. Although I get a  idea of what they are talking about.
Distortion/coloration/poor voicing of certain fq;'s in  a  given music source.
All of which will 100% guarantee result in  that~~ old ~~but ~~faithfully ubiquitious~~ enemy,  Listeners fatigue.
Some speakers I get this fatigue within minutes,  While other speakers, such as my DavidLOuis 4 unch full band,,is right on the border line. At certain full orch passages this distortion goes over to grouchness = distoryion. 
Livable, but only for short term.
Anyway, 'Here is the article,.\
Please post other tech articles which will help us all to grasp the fundamentals as to why so many xover designs suffer from these distortions in various critical band widths. 
Low bass, The  Vandersteens are like Top Dawgs, maybe highs as well, vandy's come out top desigbn. Its  in the 200hz- say 3khz where Vandersteens' have  serious issues of distortion. 

Any speaker, even Bose , has some level of acceptable low bass.
High fq's above 10k hz, just about any  xover design has accepatble performance, even B&W's has acceptable high fq voicing. 
It is the critical 200hz-say 3,4,5k hz, where xover designs get into *turbid* waters, 
have you seen how many xover components Troel uses in his bigger more full range designs??
Cost  a  fortune to build those xovers. And the result? 
Perahps lower listeners fatigue, but still it exists.
= WE have serious issues that need attention in speaker design. 
I am not at all concerned about the 40hz-200hz range , nor the 10k+hz range, Not at all. As I say, most any xover speaker gets these 2 end ranges with some degree of success.
Its that super critical mid area where all distortion can be found resulting in folks buying all sort of speakers in order to escape this syndrone, this  disease  called listeners fatigue. 
It is time to stop and think through what really is going on in xover designs. 
Lets all be honest here and admit that most xover speakers have not lived up to the hype. 

caveat
: Classical music is the golden benchmark for testing any speaker, Not jazz, nor any other genre.
That most audiophiles mostly listen to all genres, with CM at the bottom of their list, its no wonder none of  the complainst I rasie above are being considered nor accepted. 
Classical music will clearly reveal all the faults and weaknesses that you can not hear in your xover speaker. 
Its there (to SOME DEGREE), either you pretend not to hear these distortions or else you  have no clue as to  how high fidelity should  be voiced.


Vandersteen low bass #1, highs #1, Mids,, ahhh we have problems folks.

https://asa.scitation.org/doi/10.1121/1.5078770
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