Yes on it being volume limited. Dynamic range is a poor way to describe that because if they play loud enough for you (for most), they have fab dynamics. I'm speaking newer versions here. They are topologically the same but everything has been improved, especially the transformers and protection circuits. They are effectively like a point source emanating from a foot behind the speaker and nothing like a line source. It's concentric rings and nothing in line. The 6" disc represents the propagation from that point source traveling thorough that point in time and space. It also means it has uniform dispersion relative to plain as opposed to the very different dispersion that line sources and to a lesser extent even dynamics have vertically vs horizontally. The polar response of dynamics goes to pot vertically so sitting is also required for optimum character if they got the driver timing correct to begin with.
Best character from the ~6" full range center disc is limited to sitting between them for best response ( 3 folks) but who doesn't when listening seriously. The way panel speakers roll highs more slowly over distance mitigates the high frequency off axis roll for casual listening but nothing is perfect and I don't understand how that fits the discussion of bass capability.
If you look at frequency response graphs of the quad, you'll see high frequency roll. It built into the speaker with a cap and resistor because it wouldn't sound correct with more at the listening position. There is also similar down tailoring to make the bass linear but that's for a different reason.
I think you'll find that panel speakers(especially segmented ones) should be measured at 2 to 3 meters distance instead of the common 1m to get the best picture. 1m is used to help with room reflections when measuring dynamics but isn't a normal listening distance. In fact, it also totally screwed up a stereophile measurement of a Dunlavy that uses reinforcement of it's 5' spread woofers for low bass.
You are correct that dynamics are preferred for bass reproduction. For other ranges, it's up to the consumer. I don't like most panels for a variety of reasons but think the Quad is quite good but like all speakers, not perfect. That isn't what this discussion was about. I just used the Quad as an example since it''s the best known and most acclaimed example of modern electrostatics.
You can't curve a diaphragm and give it a large surface area. Phisically impossible. It needs to be segmented not to bow too much (it still does). Those modern electrostats that you speak of with bass, have none unless you add a large flat woofer panel as I described or add a dynamic. Much poorer bass response than a quad with the same panel area. They also run 1/2 the voltages, necessary larger gaps and much thicker diaphragms to make up for their design. Less control. They behave like line sources with better dispersion but their high frequency character is quite odd due to how large the radiating area is relative to bandwidth. Odd sounding to say the least. Soundlab does a better job with their segmented flat array. Let me put it this way, The qued is called the 63 because that is when Peter Walker came up with the design. It was made for 20 years because the technology wasn't there. The tech required for MLs or SounLabs was available before that.They just happened not to be. What you prefer is up to you but the quad is the most advanced tech panel out there.
Edited by goodvibes - 10/24/12 at 10:40am