so i just wanted to formally update my situation, I have completed 4 tuba45 cabs 24in wide lab12 loaded.
from an engineering standpoint and i am no accomplished engineer, if there are 3 components in the equation (output, cost, mass) it has been said that you can have any two of the three but the third component will be the compromise, i want the most spl i can get, and I have very little money, size seems to be the variable i can compromise the most at the moment. so in all of my research these bfm designs seem to be the correct application. they are complicated to build and are of the diy variety which is a plus because my labor is free to me and i like telling people that I built it, merica ya. i also like the exclusivity of the equipment, not easily repeated,
so the design is +6db abouts over direct radiator design, that means i will need 1/4th the amplifier power in the end with these drivers which saves me a ton of money,
I wanted to be capable of going low down in the 30hz area, i admit i dont have a lot of musical material that hangs out around there but i want to have it when i need it!!!
the tuba series was what i believe was going to be the best for my goals, with 4 cabs 24inch wide i should be somewhere about 105db 1watt at 30hz, with a max output of 130dbish at 30hz groundplane and close to 140db corner loaded indoors. now i admit for the 50cubic inch foot print of the rig the spl spec is not that impressive in today's market however anything capable of 130-140db on the market will require 4kwatts to operate and for a subwoofer and amplifer capable of that it will cost $4000 at least according to my research!!! and nothing i have seen that is commercially available will reach down below 37hz with any authority. so even if i went the other route i still would be shy the low extension desired. I have my subwoofer rig for a total cost of just under $2.4k and it fits my small trailer ok, i wish to include the cost of my driverack in the cost because its vital to the integration of the bfm subs
my conclusion is that there is no other way today to get as much output as i have that has as much sonic accuracy and low extension as it does for any less money than i spent that fits my current pack space.
are the Bill Fitzmaurice loaded horns the be all end all design, no they are not, a rich person with little to no pack space will likely not benefit from these designs, but for my interest and goals they are exactly what i was looking for.