Has anyone here set up a system with tiered subwoofers handling different bass spectrums?

Okay, so it seems a few people are missing some aspects of my setup here...

Firstly, the 3000 Micros are fully crossed over at 160Hz; slope is 30dB/Oct for high- and low-pass filters, and completely time aligned via REW scan/manual delay set for the speakers. This isn’t some half-assed setup where my subs and speakers are overlapping for multiple octaves. Do it right, or don’t do it at all.

Secondly the 3000 Micros are a pair that is symmetrically placed extremely near to each sub’s matching speaker, so localization is a complete non-issue and in fact imaging is significantly superior to a single sub placed anywhere. I wish I could figure out how to post images in this forum so that you can see. I actually have a paid of IsoAcoustics ISO-155 stands arriving today to really get them even better aligned with each other. Their acoustic centers are exceptionally close to avoid problems like comb filtering and poor integration--essentially, the design is meant to mimic something like Blade 2 Metas or R5 Metas (granted, I am sticking with at 160Hz crossover since that is where my room's Schroeder frequency is, instead of crossing higher which would better simulate the aforementioned 3-way speakers).

Finally, I am acquiring the PC-2000 Pro open box at substantial discount. This one will be fully crossed over to the 3000 Micros with a 36dB/Oct slope. I am trying to decide if I want to do that at 50Hz, 55Hz, or 60Hz. I debated this model against other models for quite a while and am looking to keep to a single unit. The down-firing driver of the PC-2000 Pro combined with rear-firing port will be even better protection against potential localization compared to front-firing drivers and ports, and of course this sub will provide significantly greater extension and slam than the pair of 3000 Micros do. Relieving those little woofers of this deep bass/extreme excursion frequency range will also further improve their performance up to their upper band.

-Ed

Hmm most speakers worth consideration should go down below say 100hz. 
 

Not to say one couldn’t explore a three box external crossover solution somehow. Could be an interesting if not very practical approach if done well.
 

Something different maybe.   Any speaker vendors sell such a pre-integrated design  out of the box?  Practically I’d prefer to handle large heavy speakers in three parts of even two rather than one big heavy thing that is impossible to handle practically. 
 

For example with my big Ohm F5s, the drivers are all self contained in a “can” that detaches from the cabinet “base” making overall shipping and handling much easier than most of comparable size and weight.   Very unique !

@eddnog 

How does it sound when you cross the KEFs at say 80 Hz? 

Most likely the distortion comes from the enclosure and not the drivers.

I had the original LS50s and thy sounded excellent in the bass department because they have a natural high pass filter built in- no need for filtering the signal they receive.  

As to your question, I believe REL stacks do something similar and on paper it has the chance to sound excellent.  More than you might want to spend but the theory still has merit.  

@mapman Wilson Audio's WATT/Puppy combo is a known example where the top two-way and the bass drivers are essentially separate speakers, but built to be a combination with matching crossover built in.

@avanti1960 Take a look at this chart:

https://www.audiosciencereview.com/forum/index.php?attachments/kef-ls50-meta-measurements-thd-vs-frequency-response-bookshelf-coaxial-speaker-png.145864/

Notice the increase in distortion at 200Hz and down (300Hz-700Hz range is what it is, no reasonable way to resolve that part) at these volume levels and up. By crossing over to a proper sub at 160Hz, I am offloading all of that from the LS50 Metas, and since the mid/low driver is the baffle for the tweeter (being a coaxial 2-way design), this also significantly cuts down on distortion for the higher frequencies as the tweeter's baffle is not experiencing very high excursion in order to produce deeper bass.

-Ed

I am currently doing what you are asking about. I use an active crossover/DSP unit.

I cross the subs into the mid bass cabs at approximately 77 Hz and cross the mid bass cabs into my bookshelf speakers at approximately 500 Hz.

It works wonderfully in my opinion.