being tall and with diaphrams from top to bottom?
Cool, an opportunity to be pedantic!
They're line *sources* but not line *arrays.* A line array would require multiple drivers, like the ALS or the Scaenas.
Acoustically, you can think of a line source as a line array with an infinite number of infinitely small drivers.
To an approximation, once you have about two drivers per wavelength of the highest frequency reproduced, an array will act like a continuous source, so they're acoustically very similar. (I say approximately because it's mathematically equivalent to listening to digital audio without a reconstruction filter.)
Anyway, an ideal line source would be a pulsating cylinder of infinitely small diameter. (So how would it pulsate if it were infinitely small? Beats me. I suppose it would have to pulsate with infinite acceleration. That way, it would only have to expand an infinitely small distance.) Since this can't be done in practice, a narrow driver or drivers are used, smaller than the highest wavelength reproduced for good dispersion.
Practical speakers also require some kind of crossover. A Maggie, for example, consists of 2 or 3 or (in the case of the 30.7) line sources next to one another, each handling a frequency band. The ALS has a central tweeter line, midranges on the sides (which join acoustically to make a single line) and a point source subwoofer.
An ideal line source is also of infinite length. In practice, that's hard to achieve, but nature provides a nice trick, which is that if you run a line source all the way from the floor to the ceiling, the floor and ceiling reflections make it behave acoustically like an infinite line. (Actually, losses limit that to a line of maybe 2-1/2 times the physical height, but "infinite" sounds cooler.) Shorter line sources sacrifice some power response because they don't run floor to ceiling.
