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


Since I have a slight grasp on the history or loudspeaker design. And what is possible with modern. I do wonder if we have really made that much progress. I have access to some of the most modern transducers and design equipment. I also have  large collection of vintage.  I tend to spend the most time listening to my 1930 Shearer horns. For they do most things a good bit better than even the most advanced loudspeakers available. And I am not the only one to think so I have had a good num of designers retailers etc give them a listen. Sure weak points of the past are audible. These designs were meant to cover frequency ranges at the time. So adding a tweeter moves them up to modern performance. To me the tweeter has shown the most advancement in transducers but not so much the rest. Sure things are smaller but they really do not sound close to the Shearer.  http://www.audioheritage.org/html/profiles/lmco/shearer.htm
128x128johnk
Speaker evolution these last rather many decades roughly seems to have been more about refining a concept born by Edgar M. Villchur when he brought forth the AR-1's in the 50's. Few would or should really contest the perhaps most notable feature here being the catering to a domestic demand (rather than the search for and proclamation of a more real sound), or certainly seeing a product's more widespread use through the limitation of size (made possible with the advent of the more powerful transistor amps to counter another limitation: sensitivity). Within this concept I can see some progress through the years (followed not least by an uptick in price), but in the bigger scheme of things the older, much larger and much more sensitive (horn-)speakers, though limited in the frequency extremes, to my ears are still substantially in the lead (particularly combined with low-wattage, single-ended valve amps) when it comes to an effortless, dynamic and encompassing live/emotional imprinting. From this perspective it could be argued that over a longer timeline speaker evolution has really seen a decline, in some vital aspects at least, in not re-accepting the need for sheer size and high sensitivity of speakers. From my chair we'd need to re-visit these older horn designs more frequently, and build/design further on from them to truly make progress. 
Atmasphere -Look at 1920s WE 555- 1930s 596A compression driver your saying TADs design isn't based on these early compression drivers?  Whats so different besides materials used?                                   I never knew you invented OTL I assumed it was created in 1954 by Mr Cecil Hall for EV. 
Phusis,{From my chair we'd need to re-visit these older horn designs more frequently, and build/design further on from them to truly make progress}  Much of modern design is about making things smaller maybe with loudspeakers if ultimate performance is end goal we might have taken the small approach a bit to far. 
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@johnk

What about non linear affects from compression in the throat of the horn? This usually results in high 2nd harmonic distortion. Since it is caused by air compression, my understanding is that it is an inherent design limitation of horn transducers.

Here are some measurements of various high end horns. They ALL without exception suffer from high 2nd harmonic distortion.

http://www.pearl-hifi.com/06_Lit_Archive/14_Books_Tech_Papers/LeCleach_Jean-Michel/Horn_Shootout_ETF...

I am surprised nobody is aware of this. It is not a secret.