The two situations are very different. The electrostatics and Maggies are driven over the whole area, so the nulls occur at the sides, and the bass falls off with a direct relationship to the size of the panel, as the wavelength increases then the bass output falls, in a predictable fashion. A very large electrostatic panel has a good bass response.
A cone loudspeaker on the other hand has a small dimension compared to wavelength and if there is no baffle has virtually zero bass response.
When you put the speaker on a baffle then only a relatively small part of the panel is driven, and the baffle being wider then the drivers results in all kinds of reflections with nulls and peaks, as they cancel or reinforce as they get to the edge. So, in order to solve the problem you need an active network to drive the speakers.
The late Siegfried Linkwitz did a lot of work on open baffle speakers, and
produced some successful designs but they are very complex.
However, the whole design construct is acoustically very inefficient. Moving coil speaker designs can be made much more efficient in the lower frequencies with proper loading by either Helmholtz resonators, pipes or horns. The reason is that these systems convert air pressure to air displacement controlling cone displacement and lowering distortion while increasing efficiency. The only advantage of a sealed box is reduced cabinet size, but requires brute force for a decent bass response.
I personally use pipes in my reference systems as this can provide good efficiency with low Q and provide aperiodic loading.
There is really no inherent advantage to having rear radiation in a domestic environment, in fact it tends to be a detriment. There is a lot in favor of the half space forward radiation pattern, converting to omni-polar radiation below the transition frequency, which describes most speakers. As long as the transition frequency is properly handled the results can be excellent. A small width to the front baffle is an advantage as it reduces front baffle reflections contributing to an irregular response because of peaks and nulls resulting from those reflections. That is why that concept is so popular. A bi-polar radiation pattern on the other hand makes placement very fussy and deleterious in many domestic situations. However in the right environment with careful positioning, di-pole speakers like the Quad ESLs can sound very good, but domestic environments and domestic bliss often mitigate against them.
Lastly with modern digital media and powerful amps, speakers can be constructed to produce concert hall levels and dynamics, that are only achievable currently with moving coil cone loudspeakers efficiently loaded. The design pictured by 3db. at the top of this thread is just a dumb design any way you look at it.
The Quad current dumping amps, 405-2, 606 and 909, are comfortable with loads down to 4 ohms, but not below that. A speaker presenting a load of 1.9 ohms is an incompetent design and there is no excuse for it. As Billy Woodman of ATC points out, these speakers with low impedances a crazy phase angles pretty much always have electrical resonance issues in the crossover design, but their designers are too incompetent to know it.
