Allow me to point out that there are and have long been not only 2-way, 3-way and 4-way speakers, but also 5-way and even 6-way designs. So to my mind the multi-way concept in general is clearly a scalable one, and don't let the 17-way thing throw you -- it's not fundamentally different in kind, only in degree.
There's nothing so complicated about it in theory that it couldn't be done, and in fact my supposition is that it might actually be easier to cross-over drivers whose passbands are more restricted and whose physical designs can therefore be made more similar to their adjacent neighbors. Certainly it would seem to me the crossovers themselves needn't be anything but simple, first-order types, without extra compensating elements, since each driver could be electromechanically optimized to have its flatest reponse within its narrow passband, and out-of-band misbehavior would be far enough removed to not be an issue even with a low-order rolloff, I think.
Likewise, my point about not needing 'exotic' tweeter materials, like diamond or beryllium, doesn't imply the use of "junk" drivers. It simply means that if a tweeter isn't called upon to handle 3 octaves by itself, but rather shares a divided workload, with a more restricted passband, then each tweeter can be sized optimally for its particular passband. So the elimination of the need for a relatively large 1" diameter in the top-octave driver ("large" relative to the wavelengths in that octave, in order to go down to a circa 3KHz crossover point with the midrange, as in most conventional designs) naturally leads to lower mass and greater rigidity without resorting to exotic diaphragm materials, while pushing the breakup resonance well above the audioband as well as gaining wider dispersion in the process. (A 1" tweeter becomes significantly directional above 10KHz.)
By the same token, each driver in this system would experience less excursion, meaning lower distortion (and heat), perhaps mitigating some normally conflicting motor design demands. But of course none of this would mean the drivers in such a system couldn't or wouldn't benefit from the decades of development that's gone into making drivers capable of high performance in covering much wider passbands.
For me, the question of why is it that conventional tweeters are commonly allowed to run past the point that they begin to beam in the top octave, raised the further question of just how many -- let's call it n-ways -- 'should' an ultimate speaker design be? An idealized number (like say, one)? Or an arbitrary number? Because that's all dividing the audioband into bass, mid and treble ranges represents -- an arbitrary division, having no particular physical, musical, or acoustical basis, although 3-way design can work decently, as can 1-way and 2-way designs, and we're used to it. A two-range division might have the most basis in reality: Fundamentals producable by pitched instruments and voices, and above that their overtones. But that's clearly not precise enough for audiophiles when it comes to describing either music or especially sound, which is why we talk crazy about stuff like "upper mid-bass" and "low treble", and it isn't necessarily the best engineering solution either.
How about 1/3 octave divisions, like are found in a studio graphic equalizer? Seems like too much, and again it's arbitrary. But eventually I hit on the idea -- given that the loudspeaker is the leading source of harmonic distortion (and also nonlinear distortions) in the audio reproduction chain, and given that the prevailing distortion product is the second harmonic -- that a reasonable basis for arriving at an 'ideal' number of divisions could be to take advantage of the crossover network to help usefully surpress the second harmonic of the lowest fundamental within each driver's passband, leading to at minimum half-octave divisions (assuming the minimal -6dB/octave slopes). And in this case as in many others, the minimum required level of complexity to acheive a certain engineering goal seems best -- thus a 17-way system (assuming my math and the overall concept aren't basically in error concerning this whole notion*).
But some of you posters are getting close to something that I should bring up now, which is of course that there's nothing new or unique about the idea of using many more drivers than is typical in order to help lower distortion and increase power-handling/dynamic capability, which is a big part of what I'm proposing. Elevick above mentioned Pipedreams -- just one of the designs that have aimed to achieve a simulated or quasi-line-source radiation pattern through the use of vertical line arrays consisting of multiple, closely-spaced monopole or dipole point-source mids and tweeters, and all of which I guess are spiritual descendents of the Infinity I.R.S. design, ultimate versions of which used up to over 100 drivers.
Obviously, dividing up the workload among that many drivers, with that much total radiating area and motor volume, will bring the THD way down vs. conventional singled- or doubled-driver designs, even without employing my 2nd harmonic crossover-surpression theory. So what's the benefit of considering a very 'high-way' design such as what I'm proposing, when these existing mega-designs can achieve that low-THD end using only a standard 3-way configuration? Next post...
*Here's the frequency intervals in cycles per second (Hz), calculated by starting with 20Hz and proceeding upward in 1/2-octave steps (multiplying by 1.5), rounded to the nearest integer:
1) 20-30
2) 30-45
3) 45-68
4) 68-101
5) 101-152
6) 152-228
7) 228-342
8) 342-513
9) 513-769
10) 769-1,153
11) 1,153-1,730
12) 1,730-2,595
13) 2,595-3,892
14) 3,892-5,839
15) 5,839-8,758
16) 8,758-13,137
17) 13,137-19,705
Interval #18 in this series would be 19,705-29,558, though of course there would be no need for an upper cutoff, and the whole interval may be considered ultrasonic and therefore perhaps unecessary. Alternatively, if the series is begun at 20,000 cycles and divided by 1.5 in 17 steps, it does end very close to 20Hz. In any case, the precise numbers aren't what I'm presuming to be important here -- it's that all of the driver frequency ranges are restricted such that they permit at least a >3dB surpression of the 2nd harmonic for any fundamental tone within each particular range, thus in theory providing what could hopefully be a worthwhile reduction in aggregate THD over the entire audioband.
