$5k! Whew that's an expensive pair of mini speakers.
The amount of cables, amps, power supplies, etc...Is exactly the reason I'm leaning toward active with built in amplifiers for my "someday" speaker build. More expensive but only 2 cables needed.
That's a cram packed little speaker. Did you think about moving the active 3 way section closer to center and mounting the PR's on the ends with perhaps an end cap on each? Wasn't sure if you thought about that arrangement or if it would even work.
Damn it Ricci! Your comment just cost me another $5000 because you just suggested something that opened up a whole bunch of new possibilities for improvement for this speaker! Now I can't call the speaker I'm building as good as it gets for a small speaker!
In all seriousness, I did consider that, but I originally brushed it off because if the speaker is used as a stereo pair, it would be placed vertically, and the PR's would sag from being mounted vertically, especially with all the added weight. Also, the speaker would need feets on the right side, so when vertically placed, the PR has a slot for the sound to escape. However, the protruding feets would not look nice when placed horizontally.
However, I didn't consider all the benefits that this configuration can bring that I only realized after you mentioned this again.
1. First, the speaker can be made smaller! . I really didn't like having to increase the speaker size from the planned 14" x 6" x 6" WHD to 14.5" x 6" x 7". I can probably drop the size to 13" x 6" x 7" with this configuration. The depth increase isn't so bad because it is not very noticeable, but decreasing baffle width from 14.5'' to 13'' is very noticeable.
There is a lot more baffle space for the TMW drivers, which means the driver can be placed in the same plane, like a TMW. There are several benefits
2. There is a lot more baffle area around the tweeter. This opens up the possibility to make a waveguide for the tweeter. It would be a very shallow waveguide that only controls directivity above 5000-6000Hz where the tweeter stops radiating 180 degrees and starts narrowing. This would make for a smoother power response above 6000Hz, as well as reducing diffraction effects.
3. I can use the Audax HM100Z0 midrange. This is a slightly larger but much more (~5dB higher, 93dB @ 2.83V 8 ohms) sensitive midrange. This would allow the speaker to play even louder and more dynamic than it already is, and likely exceeding most bookshelf/floorstanding speakers, but of course below high efficiency pro speakers. The 2 woofers can do ~110dB to 400Hz, but the original Scanspeak 10F mid can only play to about 102dB in its pass band. This mid can play ~107dB across its pass band. Many have mentioned this as one of the most detailed drivers ever, and some have mentioned this midrange to be even more detailed than the Scanspeak 10F.
4. I can use the Tang Band W5-1138SMF as a PR without increasing the speaker size. On the original, I would need to increase the baffle width by 0.375" if I wanted to use the TB woofer as a PR. When placed on the side, the speaker can still maintain the smaller baffle size! This woofer will provide higher excursion limits than the Peerless PR currently used.
5. There is space for another tweeter and midrange on the rear baffle for dipole configuration.
But what's potentially more interesting is that this configuration would make the speaker a lot more deceiving as it seems like the speaker only has 3 drivers, and only 1 woofer that is pumping out the ridiculous amount of bass rom a mini speaker.
So all of this would go into the V3 of this speaker. There is way too much complexity to be adding this to the V2 speaker I'm building now. I thought the V2 will be as good as it gets, and I won't be able to improve on the physical speaker itself much more. But looks like I can! However, I need a lot more knowledge in dipoles and waveguides before I can tackle this. If you know anyone that can help with waveguides, please let me know.
As to the cost, I probably only need $4000, about $900 more for extra drivers for dipole, and still not as expensive as your nuclear options! But really, even the current speaker I'm building will spank any traditional (non HE) commercial $5000 speaker for sound quality. In fact, if I do this right, it might be quite difficult to find any traditional commercial of any price that'll outperform this speaker for sound quality. It will take a special speaker, like high efficiency, horn, all out DSP speakers like JBL M2, B&O Beolab 90, Kii Audio Three, or others to outperform this. It is using some of the finest drivers available with a proper crossover implementation that takes into directivity, off axis response, power response, lobing error (where it has none), phase (linear phase), time alignment, group delay and of course flat response into proper account with no compromises to dynamics or maximum volume compared to traditional speakers. Most mega bucks high end speakers do poorly for most of those aspects of speaker performance mentioned above, which is kind of sad.