For me, I expect the extra cost due to the extra components & expertise involved in dividing the sound 3 ways & getting the directivity correct for 3 drivers, etc.
I feel that, just by being a quality 3-way, it should and would cost more. Also, due to the less economies of scale of production.
It will probably cost more buy a substantial amount for similar qualities.
Today the most important criteria when evaluating speakers is, according to Toole, the on-axis amplitude response. Second comes bass extension, and third, maybe, directivity once not too bad (otherwise it could be second).
On bass extension, is 30 better than 40, and by how much, etc. There is no unified, or agreed on metric. Of course there is the Olive ranking, but that‘s taken after the fact. The speaker has to be ready to be evaluated as a whole. Conversely it won‘t help with the design of it. It renders speaker design an iterative process.
Cost would suggest to start with a 2-way. Optimize as such, easy. Then extend the bass, or likewise ask for more output. A more capable bass/mid driver is needed. Get away with same size but more costly motor/surround, triple the cost of the most expensive component in an instant. Or go for two sizes bigger (+6dB) to make a real differences, the enclosure size increases a bit. A matching tweeter would become a challenge, horn? Conflict!
Where‘s the problem? We face unavoidable limits in cone etxcursion especially if the mids are to be played by that same cone. It is halfway mitigated by a more sophisticated driver design or, raising new probs, solved by more cone area.
But there‘s a third alternative, the third way. It would relax the demand on the bass‘es capabilities by a fair bit. You could accept HD, intermodulation in the low mids, if it wouldn’t affect the higher mids also— at least some gets distributed to lower effect on the listening experience. That would allow for the increased excursion needed for bass.
I tested the latter approach.to some success. Expensive, sophisticated bass/mid plus likewise expensive tweeter versus cheap high x-max bass, mid-driver, also cheap, and again a cheap tweeter. The subjective evaluation resulted ‚tie’ as the English may put it. No clear preference for one of them, while the 3-way in total is more practical, easier to live with on a daily basis, more consistent one might say. More undue excitement with the expensive 2-way, when played loud(er). Not too bad, even more hifi-ish, loudspeaker-like, but …
Sidenote: the digi x/over for the 3 was readily at hand, the analog mid/tweet was a breeze to do, extra amplification (Fosi 3) is cost effective. The wide dispersion is inherent to the design, and it came out to be homogeneous except for sharp, hence less disturbing (!!) interference from the enclosure‘s edges.
