Loudspeakers have we really made that much progress since the 1930s?

Technology has advanced to such an extent that the '30's can realistically be seen as the cave man days, in many respects. Certainly with computer testing and engineering, what can be purchased today for say a week's wages versus the 1930's would be worlds apart. The modern cabinet, drivers, and crossover all benefit greatly from new discoveries, techniques and a body of knowledge WRT making a good speaker that the 1930's can only dream of.

Technology is one thing, another is its application. The size of speakers (i.e.: radiation area) and their efficiency has gone from large and high to small and low, both of which I'd say are among rather fundamental factors in achieving a lifelike sound reproduction, and where advancement in technology can only bring you so far with smaller and less efficient speakers; there's no escaping fundamental physics.

An analogy: think about the state of technology in the 60's in the beginning of the space age, and where it got the Saturn V rocket and its inhabitants: to the moon - a feat that hasn't been replicated since the last moon landing in '72. You'd imagine going to the moon in our present day with its highly advanced technology and crazy computer power would be a piece of cake, relatively speaking, and yet it hasn't happened. A priority, obviously, but some 45 years ago a select group of astronauts stood on the moon and looked at the Earth - having had only the computer power of a poor pocket calculator of todays build. This is not to say the space age in the wake of the Apollo missions has been in vain, but no (wo)man has since gone that far into space and walked on another celestial body. 

Making loudspeakers that effectively approaches a lifelike sonic imprinting "simply" requires the will, skill and materials to do so, with no excuse nor catering to size constraints or other marketing-laden interferences. They apparently got off to a good start over 80 years ago, and perhaps part of the recipe here was a predominant reliance on the ears coupled with a goal that involved a natural reference, rather than an industry-established, navel-gazing hi-fi agenda where branding and small size is all-important.

This is for  Salectric here is the excellent cabinet Akers address 
http://crsacoustics.com/ P s Chris sells the Drivers also  research the Apple ply Baltic birch top stuff 3/4 thick. Good luck

I noticed no one has mentioned the Heil Air Motion transformer; that came out in the 70's I believe, and there were some two way speakers that utilized it. Although I liked the highs that two way produced, the mid-range just wasn't mellow enough.

@orpheus10, if you look back through this thread you will find I mentioned a tweeter made by High Emotion Audio. It has a lot in common with the Air Motion transformer. Its high efficiency and very fast, while also being very smooth and detailed. Essentially its a bent ribbon, pinched in the middle to give it a horn shape. It goes low enough (2KHz) that it can be used in a two-way system.

Creating a quality speaker for home use is a problem that has been solved thousands of different ways by many over the years.

Which solutions solves it best is more a matter of opinion than fact.   There are many viable candidates for that using various technologies applied.

So clearly there have been many innovations and different designs and approaches to the problem since the 1930s.   There are more choices than ever not to mention continuous refinements to quality over the years.

So other than there being more larger homes and rooms these days than in the 1930s,   the problem has not gotten much harder to solve, in fact improvements in amplifier technology make some speaker design problems, like size and bulk, easier to solve.

Needless to say it is possible to build a much higher output  high quality speaker today than in 1930.     But who needs that?   Professional applications in large venues do but cost will likely be the barrier there, not the technology availble to build the best and highest output speaker possible.