Nice thread, and something I've been thinking/exprimenting a lot with lately.
There is a sonic coherence to single driver sound that is very, very, hard to match with multidriver systems having crossovers in the critical range. Not impossible, but generally beyond the capacity of most speakers.
When done properly, it seems that music eminates from a single, seamless, tapestry - just flowing forward. And, there is a realism that can be spooky and addicting. tonality can also be unworldly.
But, like all things in audio, there are tradeoffs and problems. Bass being the biggest for me. There's no problem with deep, tuneful, bass, many achieve this. It's power, authority, and punch that is difficult to achieve. I'm talking about tactile sensation of a drummer's padded kickdrum being hit. That sudden pressurization of air that buffets your body. For that, you need driver excursion or large driver area, something most single-drivers do not have.
I've got Cain & Cain IM-Bens w/ the Fostex T-900A supertweeter pods AND a pair of C&C Bailey subwoofers. I also have the Hammer Dynamics Super-12's. Both speakers are fantastic, albeit vastly different price ranges.
You can get amazingly punchy bass with the Hammers, not doubt about it. They also handle complex passages extremely well. With some affordable mods, they can be real top performers. If anyone is looking to get into high-eff single-drivers, they are a perfect first step. You can get years of complete enjoyment out of them without betting the farm.
The six foot C&C Ben's are in another league 3 steps up the ladder in almost every capacity. And they should be for almost 18x more(w/ dual subs). Their rated frequency range is 45-36kHz. With that, I get nimble, deep, tuneful bass. The type that lets me hear all the minor inflections and decay of standup bass strings. The minute sounds os a bow drawing across cello strings. The ability to sense the wooden body of cellos and pianos in notes.
But, in both cases, I'm still in search of the chest thumping "thhtt, thhtt, thhhtt!!" of kickdrums. Or, the deep buffeting waves of kettle drums and timpani. The C&C Bailey subs seem to be primarily designed to enhance the nimble midbass and bass of the Bens instead of absolute authority.
The other factor has been sub amps. The pro audio 275wpc Samson Servo 550 amp I had for a short while was simply not up to the task. I also tried a Pro Hafler 500 amp last weekend, but the fan was so loud it was unusable for music.
I'm hooked on single drivers, but I did hear some ATC 100 litre active speakers two weekends ago that did bass in a way that made me almost want to jump ship. This last weekend I listened to some 3 way speakers using vintage 15" Truesonic fullrangers with an added midrange driver and tweeter that had punch galore. They were driven by monster 211 SET monoblocks. Yowsa!
