Single driver vs traditional 3 way loudspeakers

I have dabbled in single-driver full-range speakers.  At least with Mark Audio "Alpair" drivers, they can be quite pleasing in the right enclosure.  For me, they worked best in nearfield in MLTL enclosures.  The paper coned drivers work better than the larger metal cone drivers which for me tend to develop cone breakup in the upper midrange. 

The Alpair 7M works quite well in a MLTL enclosure in nearfield,  Nicely balanced with a very detailed and smooth sound, reasonably deep bass, exceptional imaging.  Slightly soft on top (lacks "sparkle" of a dedicated tweeter).  A little "doppler-ing" but not objectionable or bad from my perspective.  Very dynamic.  Can sound "thin" on some recordings.  Some head-in-a-vise imaging.

IMO, the Alpair 10P is the best in the Mark Audio Alpair line.  Better bass than the Alpair 7M, a bit warmer tone balance but not muddy.  Very smooth, detailed and clean.  Quite good dynamics.  Better developed / tighter / more substantive imaging - more than placement, the image has "weight."   MLTL produces good bass, I'm guessing 60's.  Very musically satisfying without warts except for maybe a slightly soft top.  

Either of these drivers can produce a very nice single driver system.  And they are inexpensive to buy and their MLTL cabinets are inexpensive to build.  For just a couple hundred dollars, an audio enthusiast can experiment with single driver system to hear the advantages and shortcomings (mostly just full dynamic range).  A good place to start.   

And it's not necessary to limit dynamics by using low watt SET amps.  I was using Herron Audio M-1 150 watt SS amps.  

Footnote:  I went back to larger multi-way systems since I have a large listening room and wanted to listen to the full dynamic range of a large symphony orchestra going full tilt at actual live levels.  I didn't want to be concerned with a voice coil wizzing past my ear.    

A 3 way design will most likely "blow away" everyone at first listen compared to a single driver.
The simple reason is that 3 ways that blow away have tweeters running hot in the 10+kHz zone, and that creates an amplified spaciality feeling. However, listening to that for extended time will be tiresome and leave you jaded as music is not like that in real life. True, real life has the "extension" but it is not exaggerated. Although I have to add you can do a 3 way (or 2 way) design without running the tweeter so hot, but then the blow away factor will tremendously decrease... and trade for the ability to actually play a wide range of music,without listening fatigue.
However, no matter how well the drivers are integrated, the crossover regions will ALWAYS make the sound more MECHANICAL.
Single driver solutions are best when the frequency range is balanced: eg 60Hz-16kHz, or 40Hz-18kHz. 60Hz-20kHz is imbalanced, just as 30Hz-10kHz. If the material is not centered on the midrange, but shifted up or down, then it will always sound unnatural. The frequency response curve has to work with the brain's natural freq sensitivity. (Look at equal loudness contours). Listening to a 60Hz-16kHz single driver has the same effect as listening to the 3 way while playing QUIETLY. When you listen at quiet to medium levels, your ears CAN NOT interpret frequencies below 40Hz or so, nor above 16kHz or so. (The quieter, the more the ears/ brain cannot interpret). So, the brain perceives a single driver speaker as true full range at quiet volumes.
Hence, single driver speakers are king when going for lower listening levels.3 ways are on a roll when you blast them.
Nowdays everyone is going deaf, and seem to be a race who can listen louder... in that case, 3 ways only.
Quiet listening - single driver is ultimate.So, next time you got a chance to compare single driver VS 3 way - try them out when playing quiet music.... and also try out how long until listening fatigue sets in. Single driver will be a winner there as well.
Every method has a compromise, we need to pick our choices to match our habits.Eg no multidriver can touch violin rendering by a single driver...and no single driver can beat taiko drums or the Wannamaker organ on a 3 way...

Picked up a used pair of Gallos recently. Little FR sphere speakers. They have their drawbacks at the ends of their range but sending them a high pass signal and letting a sub carry the low end has given me the best imaging and instrument separation I’ve achieved so far for my desktop setup.

I used super tweeters with Altec 604E coaxial for many years.
I also listened Altec 604E without super tweeters for couple of years.
For last two years I use Fostex T90a super tweeters.
It is always was some trade off between “audiophile” sound with super tweeters and more “musical” sound without.
Super tweeters make sound more refined, more air, detailed… But harsh in upper midrange, more fatigue, more smearing.
But when I changed super tweeters 1st order crossover to 4th order – the results I got are win-win! I got all the best all together! The sound is even more refined, detailed with huger soundstage and clarity versus 1st order crossover. On other hand it smooth (no harsh, no smearing), even more musical interpretation details compared to without super tweeters configuration.

I think the same should be true when using super tweeter with full range driver!
I wonder, why most people use super tweeter 1st order filters? It Is so religion stubborn stupidity!

Most of classical speakers like JBL L300, Harbeth HL5 use super tweeters thought 3rd order crossovers.