Several considerations. The first is how far off most audio components are in sound quality. It is amazing how good an "average speaker" sounds when matched to really accurate components. I think you guys have found the same thing. Second, got the room pretty flat.
Actually I have not liked any full range drivers over the years. However, ~4 yrs ago, Bill, a Rhode Island audiophile, who comes every fall to visit his parents grave site, brought a pair of 4.5" full range drivers (in small speaker boxes) with him and wanted me to audition them.
Well, I had Phast Jr. from Selah Audio (got good by on them), and they sounded better than most speakers individuals have brought over, and I could tweak them a little. Anyway, the Phast Jr. use a morel 2.5"? dome for the mids. Finally tried the FR drivers and darn if they didn't trounce the morels. Even subbed them for the Morels. Oh, I did do a little tweak to eliminate the beaming of highs.
There was some promise.
That got the ball rolling; started designing a test speaker. Something I wanted to try was to crossover at 200hz or less, 2 way. That substantially reduced the requirements of the woofer. I was sick of 45-50hz f3 response, wanted 30hz and reproduction to 20hz.
Forgot, it has been ~45 years since I designed a speaker, and I had no idea of how the project would turn out, so I didn't want to spend a lot of time. But then I have auditioned 28k speakers here and did not like them because they used an inaccurate audio system, and probably room to design them.
So I looked for a 12" woofer with a Qts of ~0.7. The woofer needed a 4.5 ft3 box; I reinforced it and installed the drivers. Internally dampened it with fiberglass.
The hardest part by far was the xover, and matching the woofer to the FR driver. That is what has taken over 4 years to get right. Besides adjustments of 1 part in some 300,000 (resistor tweak) making a sonic difference (change equivalent to frequency response change -105-110db down), even moving the speakers 1/32" rotating, sideways, height makes an amazing sonic difference. Of course temperature also a consideration.
Bought 500 watt inductors, matched to within one turn. Speakers only rated for 50 watts peak or so, using less than 20 watt peaks. Capacitors are matched (Tektronix meter) to read exactly the same capacitance in each channel.
Three controls in back of each speaker. One matches the woofer to FR driver, the second adjusts the Zobel, third is a switch that tweaks the woofer damping. Zobel caps are extremely critical in sonic quality, and uf size. I am using five foot length of 10 parallel 18 gauge solid wires from monoblocks to speakers. 8 or 12 in parallel do not sound as good.
I have auditioned the Harbeth L3/5a, a host of other speakers, heard about Fulton's, but I am finally happy with these albatross speakers. Can't even get them out of my apartment and down the stairs with a dolly though.
Frankly, they are a pain in the butt, so glad I am finished. But I sure do like hearing what I am hearing, all aspects.
The FR is -3db at 30hz and -13db at 19-20hz. Top measures to 20khz, but my hearing won't go that high anymore.
Got the flu now, gotta go.
cheers
steve