Which speakers will fill 5,000 cubic ft coherently

Springbok10 -

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What Tvad says about subwoofer implementation, however strange, is certainly true. Incorporating subs can be very tricky,as you need to place them in such a way as to blend with the speakers you have already. Purchasing speakers with pre-engineered and pre-optimized inboard subs removes obstacles that you otherwise might never overcome. It is also advantageous to consider powered speakers which have onboard amplification and generally exclude passive crossovers and the compromises they introduce. The better powered speakers often have a separate amp for every driver and an electronic (active) crossover on hand to handle crossover points and slope assignments.
It is also advantageous to reproduce as wide a midband as possible without crossing over at all. This is usually the province of very small limited range dynamic drivers like Lowther and Fostex or rather large planars like Sound Lab or Magnepan. The former will not begin to fill your spave and the latter is too large for where you need to put them.
While we are at it, Beveridge is not only too large to fit but needs surrounding space which you certainly can't provide. Another suggestion called for Infinity Kappa Nines. These, if I remember correctly, hold a special place in the H.O.F. for hardest to drive speakers of all time. A very, very unwise choice for an OTL owner.

I'm a Zu guy as is well known but there are some other speakers that might suit your purposes. Perhaps Vandy Fives would fit.

>>3-22-08 Macrojack :I'm a Zu guy as is well known but there are some other speakers that might suit your purposes. Perhaps Vandy Fives would fit. <<

Not Coincident Total References?

Specifications:

Frequency Response: 20 Hz – 27 KHz
Impedance: 8 ohms (never dipping below 6 or going above 10 ohms)
Sensitivity: 97 db @ 1m – 1 watt
Power Requirements: 3 watts – 500 watts
Dimensions: 56.5” H x 9” W x 24” D
Weight: 230 lbs ea.
Driver Compliment: (per speaker)
1 Isodynamic Planar Ribbon Tweeter

4 Carbon Fiber 5.25” Midranges

4 Nomex Fiber 12” Woofers

I'd concur that integrating a good sub effectively with a pair of speakers definitely improves upon soundstaging abilities of the mains in my experience. These improvements have been in the 3-dimensional depth and width of soundstage, and in pinpointing and resolving images in space. It does not, in my experience, however, do anything to increase the "vertical soundstage" (from your original post)...or at least what I'm interpreting your meaning of that to be, which is to say, the scale of imaging. Though more impactful (did I just made that word up) in ways I have never found it to increase the scale of the images produced by the mains. I have certainly heard systems where the scale of the imaging seems larger than life, as it were (I'm assuming this is what you mean by "vertical soundstage"). I'm not sure that I'd appreciate that on a long term basis though. Perhaps. It certainly is a novel experience when I hear it. I wonder if the novelty would wear off. I don't know what qualities speakers/system need to have to pull that off. One such system that impressed me that way consisted of NHT 3.3's and all top-shelf Levinson gear. It wasn't my cup of tea, but it was memorable and impressive in many ways. The scale of everything it reproduced seemed larger than life, and the space it was in was quite large itself, both in footprint and volume. A piano seemed larger than it should in real life and human vocals made the singers feel like giants in some way. If you are looking for this from a speaker/system that doesn't already render something like it already, I don't think a sub will move the sense of scale in that direction. Apologies in advance if I've misinterpreted your meaning.

How about Vandersteen 5A's? Builtin sub amp - easy speaker to drive and fills my room perfectly - 23x15x14 with open back.