@thespeakerdude wrote:
Hence bracing, The large the panel dimensions, the greater the bracing. A superior shape is of little benefit if we cannot manufacture it, added shipping costs ameliorate the benefit, or it causes difficult in use for the customer. ...
Hence DIY; in principle every design, shape and size (and weight) can be pursued. I’ve gone the horn route with subs where the horn "innards" are elaborate bracings. Large behemoths, but constructed in 13-ply BB with CNC-cut and interlocked panels they’re very sturdy. Further damping can be applied and accommodated as one deems necessary.
Distortion isn’t only cabinet vibrations but as well mechanically induced noise from the direct radiating and exposed woofer(s) during high excursions. Horn-loaded woofer cones, while concealed inside the horn, move very little for a given SPL, potentially both due to high efficiency and the way the woofer cone can have minimum excursion at the tune (via Tapped Horns; not the more traditional Front Loaded Horns where the woofer is usually placed in a sealed chamber). Avoiding mechanically induced noise here is not trivial.
Very few audiophiles have been "exposed" to the sound of horn-loaded subs (or their variants), not least for the reasons you outline as a MFR, which is a shame, because they deliver a very smooth, enveloping and effortless bass reproduction when carefully implemented - certainly audiophile qualities in bass reproduction to aspire to. Their ability to produce truly prodigious SPL’s is part of their perceived prowess here (and so not only about loudness per se), because significant headroom equates into cleaner/less distorted and more relaxed bass.