I've never heard a single driver dynamic speaker that I thought I could live with - there's always a deal killer at some point in the trade-offs that have to be made.

Now, electrostatic/planar single drivers...those I could live with. Do those count?

As you note with your system, you're not using a single driver...you have a tweeter for 10K and above. I've heard some greatness on some music with single drivers and utter cacaphony with the same speaker with other types of music. I may be a boorish rock'n'roller, but they just don't cut if with loud, complex rock passages. But hey, if you love your system, who am I to judge.

The function of a speaker (driver) is to create ripples in air. Big ripples, small ripples, medium ripples. If that were the only part of the function, it would be simple. But a speaker must produce all the size ripples at at the same time, or some combination of sizes at the same time.

So while the cone moves in and out 100 times per second, it is also moving in and out 200, 500, 1000, 10000, 20000 and any number of place in between. Kind of like driving your car all speeds at once.

So, any electro-mechanical effort a driver uses to hit one frequency must take something away from another frequency. There simply are not enough resouces to do all the tasks.

By using different drivers for different tasks, you reduce the workload of the other drivers and allow them better control of the task at hand. Dragging physics into this, you cannot take a large (heavy) cone, needed for lower notes, and expect it to accurately move at the frequency required for higher notes.

So, IMHO, single driver loudspeakers almost always loose dynamics and corrupt the highs.

Graph from my site under Hertz101

Disclaimer: This chart is for conceptual use. I chose four octaves plus one octave for the distortion/roll-off range. This is to define the best operating range for any "Joe driver". Clearly this does not present all drivers in any size group. Many drivers have a broader operating range than the six octaves shown, particularly very expensive drivers and really cheap drivers A driver's published range is usually the mechanical limit, not the distortion limit. Before you write me to tell me I am nuts, consider two questions: 1) how far below the f3 are most drivers at the bottom of the yellow range; 2) how bad is the off axis at the top of the yellow range? And please don't write me about your 4" driver that goes to 20Hz in a TL.

what is hot in single driver speakers would be Zu Druids and Definitions. I know they're not strictly single (tweeter above 12k) but in fundamental character they are, plus 101dB efficiency. Visaton B200s in resisitve port boxes by Omega are also pretty interesting (96dB) and truly single driver. Both have been enthusiastically discussed on Audio Circle
http://www.audiocircle.com/index.php?page=2

Neat chart pjay!

My 4" 'single driver' TB's sound really good.

http://www.zillaspeak.com/PortQ.asp

I still haven't figured the box yet... and they do need a tweeter and (sub)woofer for best sound. Very clear and good sounding without.... but also without much volume or slam factor. I think they will make a wonderful extended midrange and look forward to listening to them.

Peace,
Godzilla

Single drivers, or two for stereo, are fun for listening to music. Explaining why this is impossible is also popular ... Just get a pair and see if you like it or not. Physics is great mental exercise, but, it is not the only worthwhile human pursuit

I use a pair of "full range", 8" dual cone speakers in my kitchen. They are vintage drivers and mounted in semi-open baffles. I use a tiny 10wpc(20 max)amplifier to drive them and they sound quite nice for the application. We also have a proper 2-way set of Focal-JM Lab speakers in the dining room that are vastly superior (and equally more costly of course). Rather than to have to suffer mono sound due to the walls between the dining room and kitchen, I set-up this small set of on-wall speakers for use in the kitchen. It also allows for individual level adjustment for each room of course.
-Bill

A single driver speaker (although it's tweeter technically makes it a two driver unit) that is often overlooked is the Tannoy Dual Concentric found in the Prestige, Kingdom, and Prestige line.

http://www.tannoy.com/PrestigeOverview

Still a very entertaining design IMHO.

How about the Ohm Walsh? Pretty damn good today and even 30 years ago.