Which sounds better 2 way or 3 way speaker design

All I can say to that is dhh, for the obvious! 
well wired, quality engineered, the wider the sound stage period. I’ve 4 column 5 ways that out perform most 2-4 ways hands down. Little speakers are just that…little !
Happy new year 

Cheers 

The crossover design is critical with both 2-way and multiway speakers, but it’s considerably more difficult to achieve balance and coherency with more than two drivers. If the objective is for the speaker to be able recreate a music wave realistically, with all harmonics intact, the wave has to have a consistent shape and amplitude, and the correct phase and timing whether it’s coming from one driver or multiple drivers....the more drivers you add, the more difficult it becomes to recreate that music wave and have it replicate the original.

Single driver speakers have appeal because of their simplicity and lack of a need for crossovers to shape the sound to reproduce a music wave. Their phase coherency is excellent, and they tend to have less smearing and latency caused by crossover components. Their downside is that when frequencies that are smaller in diameter than the driver, those small frequencies tend to beam straight ahead, and have poor off-axis performance. The larger the driver, the more beaming.

There is always a downside to every option, but the marketing hype leaves that part out. Thus opinions that are formed based on the same marketing hype tend to echo only the upside, unaware of the disadvantages. Making an assumption that more drivers are better, is similar to saying more salt is better in all recipes.

@ditusa wrote:

See here a two way monitor with attributes of a three and four way design.

Mike

+1

OP: There are a lot of variables involved here. As has been pointed to by several in this thread already it’s about the design goals and juggling different trade-offs, however pragmatically speaking design goals may take a backseat to what’s dictated by the physical outlay of the speakers and the kind of drivers that’s typically used; a 1" direct radiating dome tweeter only goes so low (i.e.: ~2kHz), and in a 2-way design an 8-10" woofer/midrange is about as far as it goes in size to sufficiently "meet" that dome tweeter above, and at the same time avoid severe beaming or break-up modes. The woofer/midrange in such designs will cover most of the voice fundamentals (both male and female), while harmonics are sitting much higher in the treble range of the tweeter. The downside is IMD and Doppler distortion with a single driver covering bass both LF and midrange, and coming down to it there’s also only so much such a driver pairing can do macro dynamically. The power response at the crossover usually isn’t great either, making more obvious there’s a driver division here. Introducing a dedicated and well-implemented midrange driver for a 3-way design (i.e.: where a direct radiating tweeter is used) to my ears tend to be an advantage, both in freeing the mids driver of LF and being given the opportunity for more woofer displacement, even if it means high-passing in the lower midrange area.

On the other hand, waveguide loading a fitting, relatively low fs 1" dome tweeter with a properly sized and designed waveguide can significantly lower the crossover point to the woofer/mids (fairly comfortably down to around 1kHz) while also providing for a smooth directivity pattern at the crossover, significantly lessening the influence of crossing over in the vital midrange area. This way a larger woofer/mids can also be used with up to about 12" in diameter, and with a higher sensitivity pro woofer the dome tweeter can be replaced with a compression driver, and now you suddenly have a high sensitivity 2-way design with smooth directivity characteristics at the XO and prodigious output capability. Depending on the specific pro woofer choice LF may be restricted and which then calls for augmentation down low with subs. This way we’re entering what’s effectively a 3-way design of a different type, and with the further opportunity to highpass the woofer/mids driver with even cleaner lower to central midrange to boot. To my ears such an effectively 3-way waveguide-loaded design choice has a lot going for it.

Many of the larger high output JBL designs with pro/studio origins (as referred to by poster @ditusa) adhere to above model being waveguide or horn-loaded 2-way designs with compression drivers and 12-15" woofers - sometimes augmented with a super tweeter above 10-15kHz, but which nonetheless doesn’t deter from the fact that they are basically 2-way designs. Myself I also prefer what is basically a 2-way high efficiency design variant crossed at just over 600Hz, though augmented in either end of the frequency range with subs and dedicated high eff. slot tweeters (i.e.: <85Hz and >11kKz). With only a single XO-point in most of the audio band that clears the power region and has neat power response, the augmented areas, and thus technically a 4-way setup, help in ways that doesn’t impede with but rather exacerbate the basic traits of a 2-way approach with a virtually unlimited macro dynamic envelope to boot. Being also that my speaker setup is configured actively, delay has been carefully implemented at the XO points, and having most of the fundamentals of the central midrange + harmonics covered by a single large format horn + compression driver element is a major advantage.

Not sure anyone knows what a two and a half way is

I agree that it depends on the speakers and other variables such as room size and configuration. I recently replaced 3 way tower speakers with 2 way stand mounts and the 2 way speakers sounds way better to my ears. Improved soundstage, mids, and tighter, more well defined bass. In all fairness, the 2 way speakers cost more than double the 3 way towers (13K vs 5K) and are much better suited to my small listening space. I did not conduct a comparison in a larger room at a greater listening distance.