Naim DBL

Here's a start, Stereophile review & measurements of the NBL speaker

We can gather the crossover points & slopes, frequency response, connection polarity from the review.

I think it uses the IBL drivers (Scanspeak 8513 w.o ferrofluid & custom 5" mid) and stock ATC Studio 15" Bass woofer.

The ATC is mounted in a small chamber that loads into a larger sealed one. The hole between the 2 chambers are aperiodic, there's some kind of resistance material. It is similar to, if not exactly like the ABC bass loading that REL S series subs & the old North Creek Pegasus speaker does. Naim SBL also does something similar.

North Creek's white paper determines the volume of the 2 chambers to be of 1/3 and 1 of the ATC woofer's VAS. This is the only documented stuff on ABC i know of. You can also determine the volume by measuring each of the DBl's enclosures.

The smaller bass enclosure is suspended fromthe larger one. Both are suspended from the Mid/tweeter enclosure, thus the rack like thing at the back that supports the mid/tweeter enclosure.

That's all i know/can guess. Good luck!