Any Large Acoustic Suspension Speakers Being Made?

Sealed box and acoustic suspension are not identical. All acoustic suspension loudspeakers are sealed, but the opposite is not true.

Sealed enclosures are obviously unvented, but the box is big enough to leave plenty of room for the back wave, and the speaker drivers have normal suspensions, rigid frames, and strong magnets to return the drivers to the neutral position.

Acoustic suspension speakers rely on a specific volume of air to power much of the rebound to center after an excursion or incursion of the driver. Thus the acoustic suspension model doesn't need as powerful a magnet, nor as rigid a cone because the air in the sealed box performs much of that function.

As for sealed box speakers, both Magico and YG use sealed enclosures. I'm sure there are more.

One thing about the Dunlavys (and the Duntechs that preceded them)  that is very important to some people is that they use first order crossover slopes, and also that the drivers were staggered to be time-coherent.  Not that many speaker manufacturers do that these days (Vandersteen, Green Mountain, Thiel).  There was nothing really that special in terms of parts in the crossover (although they did use air core inductors, I think), and some A-gon members have made upgrades to the parts in the crossover with some success.  All in all, it was an extremely well-engineered speaker.

rcprince: If you read the Stereophile review of the SC-IVA, you’ll notice the fanatical attention to detail Mr. Dunlavy used in building his speakers. How about a frequency response of +/- 1.5%? He would hand-trim every crossover to match its companion driver. Mr. Dunlavy said this speaker could pass a square wave better than most tube amplifiers! I would love to hear these speakers driven by BEL 1001 Mk V amps (also built with fanatical precision). Try to find a maker that would go to these extremes today!

PBN Montana KAS-2, WAS-2, and Master Reference.  Similar to the Dunlavy speakers, but look better, built better, use better parts and drivers, and IMHO sound much better.  All this comes at a cost.

I also agree that the PBN Montana speaker is similar to the Dunlavy but a good bit better. I have owned the Dunlavy V so am very familiar with their sound. Have owned the PBN Montana EPS 2, and currently using the WAS 2. If you liked what you heard from the Dunlavy's you will LOVE what the Montana's do.

Must investigate!

(((I also agree that the PBN Montana speaker is similar to the Dunlavy)))
 How can you say this?
 All they have in common is both are a large box design.
 one has 6 DB per octave the other steep order
 
 (( Mr. Dunlavy said this speaker could pass a square wave better than most tube amplifiers!))  If square wave or timing is important
 You would need to check out a 6 DB phase and time correct design
 or ask the question is your speaker out of time?
  Best JohnnyR

All I know is that I had a "eureka!" moment with the Dunlavy SC-IVAs.
Everything sounded real -maybe better than real -everything.
This speaker was obviously conceived and built by a master of the art.
Of course, there was probably some "paradigm shock" involved.
I.E., when the mind is exposed to something significantly better than it's used to, it tends to overreact and possibly hear things that aren't really there. This wears off in time as it becomes the "new normal" and the "searching for something better" cycle resumes (seeking the next "eureka!" moment).

dweller,
you did not realize this at the time but you were ahead of the game when you had that eureka moment listening to the SC IVA speakers. The sonics from that speaker had less to do with the drivers being acoustic suspension & had a lot to do with their using 1st-order x-overs (like rcprince wrote) & the fact that John Dunlavy designed them to be time-coherent. I've seen time-coherent speakers to be ported & sealed box with the sealed box speaker giving a slightly better quality of bass. Careful design of a ported time-coherent speaker can yield very good bass as well.

In the S'phile review link you posted if you look at Figure 8 in the measurements JA took you can see step response of the SC IVA that clearly shows the time-coherency of the speakers - the sound waves from all the drivers reach the listener's ears at the same time - there is just one rising edge. In speakers that are not time-coherent you will see several rising edges as the various drivers sound waves reach the listener (look at the step response of any B&W speaker in S'phile's reviews).

if you wanted to repeat your eureka moment again today you would need to buy another time-coherent speaker. Unfortunately Dunlavy speakers are no longer a choice but you do have several other choices - Green Mountain Audio, Eminent Technlogies, Sound Lab ESL, some older Quads (maybe even incl the original ESL 63), Vandersteen, older Thiels made when JT was still living.

The use of a 1st order x-over in time-coherent speakers is not a coincidence - the math shows that a 1st order filter is the only filter that will preserve the phase relationship between any 2 signals over the entire 20Hz-20KHz region. All other higher order x-overs can only maintain the phase relationship at the x-over frequency & over a very small freq range above & below the x-over frequency. That makes speakers using higher order x-overs only phase coherent (which is quite easy to do for most speaker designers) but it is far from sufficient to give the listener an eureka moment when listening to music.  I've been harping about time-coherent speakers for quite a while & how they are the only way to go if one wants to listen to music with a realistic sound over the long-term i.e. get off the speaker merry-go-round. Fortunately for me a few Audiogon members converted their existing speakers to time-coherent using software (DEQX) & they have reaped tremendous benefits from doing so. They couldnt be happier....

it would be great if you could read thru the following threads so that you can educate yourself about time-coherency & its high importance to speaker design & music playback. Sometimes these threads ramble on - needless to say skip over those sections & concentrate on the important posts esp. those by Roy Johnson (of Green Mountain Audio):

https://forum.audiogon.com/discussions/is-deqx-a-game-changer?highlight=is%2Bdeqx%2Ba%2Bgame%2Bchanger

https://forum.audiogon.com/discussions/sloped-baffle?highlight=sloped%2Bbaffle

https://forum.audiogon.com/discussions/time-coherence-how-important-and-what-speakers
(this, i think, is the best thread ever in Audiogon. it's really long but there are many details & technical discussions re. time coherent speakers that are very enlightening. Try to comprehend & assimilate the info in this thread. if you want to read just one thread, this would be it).

bombaywalla: I agree that the first-order crossover is probably what did it. Furthermore, I think what sets these speaker apart is Mr. Dunlavy going the extra mile and hand tailoring each crossover section to its respective driver. Most manufacturers probably arrive at their ideal on paper and assume that "if the parts we receive from our supplier are within spec then the speaker will sound "good enough"". Mr. Dunlavy was a true believer and why I got into high-end in the first place. Unfortunately, my means at the time didn't allow me to purchase the SC-IVAs. I'm moving back east (from Las Vegas) and will be assembling my last system.
Hopefully, I'll find a speaker close to the Dunlavys. 

George, The Alexia is way-more speaker than I need. I'm thinking about some used Sashas partnered with the new D'Agostino Classic stereo amp and an Audio Research Ref 5SE. Can't see needing more than this in my Golden Years...

If you have the room you might consider checking the ads here from time to time, used Duntech Sovereigns/Princesses and Dunlavys show up from time to time.  While I sold my Princesses after about 15 years with them, I still have a soft spot in my heart for them.

I shy away from equipment when the original maker can no longer fix them.