Every now and then I check in to see what's going on and saw this thread on wide range Imperials.  I've built more than one set of these speakers over the years, the latest set with additional bracing similar to Steve's SO design that was not in the original plans.  Coming from both an EE and orchestral concertmaster background, I would underline Steve's caution about determining your application as absolutely critical.  I wouldn't build the SO because I have no interest in music that goes below 30Hz, the 5db down point with the original lab design at left.  For those who do, and want a boost in SPL at the lower end, more power to you!    That kind of boost just doesn't sound like what I hear sitting on the stage in a large orchestra and being a part of recreating a classical piece of music.  Like every one of you, I've listened to a lot of speaker designs, and can only say that for orchestral and pipe organ program material, the original design using the G-610 is still hard to beat.  You won't get the bass you feel with the SO's, but you won't hear that in the concert hall, either.

Unfortunately, there are so many variables that it is almost essential to hear a pair in your listening environment and with your kind of music.  Those variables can range all the way from the equivalent of a dummy load in antenna terms (Imperial in a van) to an infinite impedance load (an open field) and all the classic transmission line matching equations and techniques (in sonic equivalents) apply here.

Best wishes,
Mike

Get what fits is the best advice.
sometime you really have to take a look at the room, the music, and what you wanna hear in it.
Then make a leap by what people with the same tastes in music say about it. Can't say any one speaker will last to your dying day for most. tastes changes
Sometimes even a speaker that you look at and say " boy I like those" after all the other needs are met.

just one other thing i have learned.
take 1 box and lode it with a 15 and a horn then listen to it .
then take what you just listened to and go to a school then a bus stop and so on.
it will in most cases always sound different just like any design from here or any other site.
for a test i built a 4 ft cube box and made plates for different drivers and also ports that i could cover and open.
then i used a small powered sub amp and x over that you would find in a store bought powered sub.
now i did this so i could better understand speaker specs and WOW they are alot of thing i found out.
my first test was with an 8 inch driver i had from mcm in the box with no port i could drive it to where it would pop but there was no audible sound of bass.
so i uncovered a port and instantly BOOM BOOM BOOM .
I did this with 9 other drivers and all were differnt.
so my point???
you may have a killer box and a killer driver but maybe not a killer match.

happy building.

shayne

Relax Geoff.... As I figured,  you're reading into things way too much.   It's sort of like how Al Sharpton finds racism in everything.   Just wanted to keep everything on this thread on a serious note.

I'm getting close to making my next builds.....  I'm thinking about driver selections, and making it a 3 way like the old one was.

Adding a second speaker yields a 3db increase. Adding twice as much power yields a 3db increase. Adding a second speaker, and adding power to it(doubling the power of the channel) yields a 6db increase.

Not to mention that quote is confusing as hell because he mixes up Acoustical and Resistive in the last paragrpah totally changeing the meaning...

The quote makes more sense if you understand the way a front-loaded horn works(as opposed to an Imperial). All sound from Bill F's designs comes from the horn; there is no direct radiation from the cone. Front-loaded horns have a much stronger influence than the T/S parameters of the driver. I have probably oversimplified this and I'm sure Bassboy and others will be helpful in expanding the concept.

As far as electrical impedance, if two drivers are splitting the power, do you really get 3dB increase? This is one of the most debated ideas I have seen over many forums. Doubling the cone area then splitting the same amount of power(one variable at a time), do you get an increase? Or do you have to give each speaker the amount that the single drive got?