Why Aren't More Speaker Designers Building Augmented Widebanders?

Here is a paragraph excerpted from Laurence Borden's July 2014 review of the earlier Bache 001 for Dagago. I think it gets to the heart of the augmented widebander advantage:


"In a typical 3-way speaker, the crossover point between the midrange and tweeter is typically between 1 and 2 kHz, which is smack-dab in the region to which our ear is most sensitive. No matter how well designed a crossover might be, the tweeter and midrange drivers invariably differ in their dispersion characteristics, transient response, and distortion characteristics. Making matters worse, the crossover often introduces phase shifts. Although these differences are often not recognized per se (except in especially poor implementations), they become apparent when they are absent, as they are in a speaker based on a wideband driver. As implemented in the Bache Audio speakers, the Tangband covers the range from about 100 Hz to about 10,000, or almost seven octaves. Not surprisingly, they are superbly coherent. As a result, music has a wholeness — or oneness, if you prefer — that makes it seem more lifelike. One has a sense of being more relaxed while listening, a trait I find very desirable in a speaker. Not surprisingly, instruments that span many octaves — like the piano — are especially well served, yet all instruments benefit".

Here's the link to the full review:

https://www.dagogo.com/bache-audio-001-loudspeaker-review

I don't remember it all perfectly, but I recall that the 3 inch or the 4 inch Tang Bands either one needed to be crossed around 200 on bottom and their  maximum usable frequency to keep within very tight tolerances was about 5k.... again on either 3 or 4 inch full range bamboo driver.  I guess that I could have played with other models, but at the time, there wasn't a lot of choices,  but from 200 to 5k, they were fabulous, easy enough to build a world class speaker. 

The W3 series, both ferrite and neodymium play out to 20 kHz.  The neo has a flatter frequency response, but they’re both very good drivers.  Going back to the OP, I think one of the challenges ( at least for commercial production) with crossing so low is that the crossovers end up costing more than the drivers.  Re-capping mine with Mundorf Supremes approaches $500.00.  But, I’ve built a few speakers with the typical 2nd order L/R at 2000-3000 Hz crossover- using pretty decent tweeters- and the wide banders come out on top.  I’m not sure why—they just sound more coherent.  And despite the fact that I’m using large values for caps and coils, the parts count is actually pretty low- not a lot of parts in the signal path- which might explain why they sound good.  Some of these designs use a simple first order x-over on the woofer and second order on the FR.  With impedance equalization you’re looking at maybe 5 components in the x-over, maybe less.  Compare that to the parts count in a 3-way.  

Another good design is the Silverline Minuet Supreme. 3.25 inch woofer crossed to the tweeter @3500hz. The little woofer can play very high and the tweeter only comes on for the highest notes, delivering the airy and delicate top end that a widebander can't. Crossed over to the sub @60hz makes for a really nice small room or desktop setup. Icing on the cake is that it's easy for a tube amp to drive.  

My mistake on the Altecs! They are the 755 series, with the 755A's being the most desirable because they claim to be built by Western Electric. I had a pair of 755E's. Not as rare, but still sounding fine (and a lot cheaper!). An excellent DIY choice for a 1 driver system. They particularly excell in the midrange!