Why not acoustic suspension?

@dynamiclinearity 

Are you saying this was never an acoustic suspension design?

I think of any sealed air tight enclosure as Acoustic Suspension. What am I missing?

It is not always about a smaller enclosure: bass extension can be improved by getting more sealed cubic inches than the original smaller compartments in the original Fisher Console, and then an optional Vent was added. I used the vent open when the speakers were located with a fully open room behind them (no longer Acoustic Suspension). They sounded muddy when I moved here with a wall several feet behind them, so I sealed the vents closed, in my mind back to Acoustic Suspension.

The drivers started out in ’smaller’ sealed compartments (no vents or ports) within my Uncle Johnny’s Fisher President II. It was up on 8" high bronze legs, the woofers fired downwards. The 15W Woofer did what it could in those many cubic inches.

https://www.audiogon.com/systems/11420

1st move: I had identical sized separate cabinets made, in white oak, with chrome tubes for an 8" high open base (anybody remember ’abstracta’?), the woofers still firing down. I simply moved the original front panel with two horns mounted, new fabric wrap. 

2nd Move, to change to front firing woofers, I had a taller pair of English Brown Oak cabinets made, woofers now front firing, no vent or port, a small increase in sealed volume, thus theoretically a bit more bass extension, and better imaging from the front firing bass and bass overtones.

I just found the drawings I made for the current Rosewood enclosures. Those enclosures are air tight sealed enclosures, OA 36" h; 20" w; 19" d.

Width to fit the 15" woofer became 20; depth of woofer in front of the optional port in the back panel behind it, avoid square, became 19", and ’not too high’ but more cubic inches, we chose 36" with a net volume (deducting the port’s volume) of 6.01 cu ft.

The optional 3D rectangular port (not visible, it’s built into the removable back panel) (10" w x 5-7/8" h x 4-7/8" deep) was designed with the help of Electro-Voice Engineers who were still in NYC. Use it closed, or open. It is sealed air tight now. 

Eliot, your speakers are not acoustic suspension. With the port sealed they are closed box but not acoustic suspension. A closed box is acoustic suspension when the air in a sealed box has a significant affect on controlling the woofer. If the woofer works in a ported box the spider controls the driver moving in and out and  air affect in the box is minimal. Acoustic suspension occurs when the air in the box is necessary to restore the woofer to neutral. It implies a soft spider that can't do the job on its own. Even if the box is closed and the spider controls the woofer it still isn't acoustic suspension; it's just closed box.

The problem with the nomenclature occurred because in the 60s acoustic suspension was 2/3 of the market. When Thiele/Small did the math so reflex boxes could be designed on paper without guessing like it was before acoustic suspension went out of favor. But since acoustic suspension at one time was almost all closed boxes people forgot that it wasn't a synonym for closed box and recalled the popularity of the term acoustic suspension and started using the terms interchangeably in correctly. Edgar Vilchur who founded Acoustic Research and along with others, especially Henry Kloss made acoustic suspension popular would be rolling in their graves at the misunderstanding. If you understand math set theory acoustic suspension is a PROPER subset of closed box.

I listen to AR9's that are 45 years old. They, to me, are the perfect example of the old acoustic suspension system. They were a reference speaker of their day. Many things have come and gone in the last 45 years. I still enjoy listening to my AR9's, nearly every day. They have the bast bass that I've ever owned, maybe the best that I've ever heard. They are no slouch in mid or highs either. They are a very well designed speaker system. I would never get rid of them. I might try something new at some point but if I don't, I'm OK with what I have as well. 

The AR9 was real acoustic suspension but a hanger on. By that time bass reflex had taken over. It became harder and harder to do acoustic suspension as bass reflex took over. Many(most?) speaker companies buy their drivers from a few main suppliers. And the suppliers build what sells. And bass reflex was what was selling. To get an acoustic suspension woofer you either had to design your own or pay a supplier to build something special for you which, of course, is more costly than standard designs.

And closed box is hard to sell now. It sounds different. Bass reflex sound is what most people have heard and what they think bass sounds like. There are very few closed box designs today. Off the top oif my head there's Magico, a top of the line design. But I don't know if they are acoustic suspension or closed box though I think they use the term acoustic suspension. They use closed box because they know it has less ringing that bass reflex.

@dynamiclinearity Wouldn't Legacy Focus SE be sealed enclosures? 

I may be too old school to "like" the new stuff. I really don't know. I get curious about the open baffle stuff, find it interesting but that's about as far as it goes for me. I have absolutely nowhere to listen to any new concepts or designs. I am very accustomed to what I do listen to and I don't ever get tired of it. I also have a pair of KEF R107's. They have a nice sound as well.