single driver speakers

I cannot answer for the speakers above but I have built field coil speakers that will take your breath away.  The need a fast sub to integrate with them but you cannot find or hear any other speaker that has the speed, clarity and musicality of them.  The drivers used cost $3500 and up per pair that I used in building them.  They are powered by a external power supply no crossovers here.  

Most speakers today are permanent magnet which means they have a fixed magnetic field created by a magnet. With a fixed magnet speaker the voice coil is suspended in a gap between the poles of the magnet. The voltage that is applied to the voice coil causes it to move in and out.

A field coil speaker uses two coils; the voice coil and a field coil. Instead of a magnet, DC is applied to the field coil creating a magnetic field. This takes the place of the permanent magnet in creating the fixed magnetic field. Field coil-based drivers claim to drastically reduce distortion levels, and are able to control the driver much more accurately. Drivers in speakers vibrate up to thousands of times per second. Some claim that permanent magnets actually lose strength slightly with each vibration, causing a loss of low-level information and a blurring of the signal. Field coil drivers, with their own power supplies should not lose strength and so have much less distortion than their permanent magnet counterparts.

Like electrostatic speakers, field coil speakers have to be plugged-in to work. The sound gets more relaxed as you lower the voltage, and the highs and lows will be more extended and detailed as you raise the voltage.  What you hear is just pure music beautifully reproduced.

Hope this helps.  Happy Listening.

single driver speakers can do good only on vocals and string quartets.
nothing else will be sounding up to par no matter whatcha do.

@czarivey 

I heard the Cube Audio Magus speakers at AXPONA, they were playing a lot of old-school jazz and big-band (Duke Ellington, Louis Armstrong, etc).  It sounded great - a lot more bass than you'd expect from a single-driver (the cabinets use quarter-wave transmission lines, so I'm sure that helped) and the treble was smooth and pleasant, I didn't feel like I was missing anything in the sound of the trumpets for example.  

I don't know how well they'd hold up to a full orchestral recording of Mahler's 2nd or Shostakovich's 5th, or if they'd be able to throw down some hard rock, I have a feeling that the single driver could easily get overtaxed if asked to reproduce a huge frequency range at high SPLs, but for what they were playing they sounded fantastic.  

@czarivey  -  'single driver speakers can do good only on vocals and string quartets nothing else will be sounding up to par no matter whatcha do.'

You have obviously not listened to the latest in single driver speakers.  I also heard the Cube at AXPONA and agree with tutetibiimperes on how good they sounded.  I have been the very happy owner of a pair of Omega Super Alnico Monitors, which are single driver speakers, and they are very good not only on 'small' music ranging from small acoustic combos, string quarters, Schumann vocal pieces, but also on 'larger' and more expansive music including Mahler (1st for me), Pink Floyd, the Who, and movie soundtracks (e.g., Pirates of Caribbean, Gladiator).  Granted, one will not get the deepest vestiges of bass or sustained very high SPLs from a 6.5 inch driver, but they sure can convey an incredibly satisfying and realistic aural picture across a very wide spectrum of musical styles.  You owe it to yourself to go out and hear what today's designers using single drivers are capable of achieving.

I heard most of Lowther single driver designs and made my conclusions after listening few. I couldn't become SET/single driver dude sorry.