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

I think if we go from one type of technology to another, it's impossible to say things got better or worse.  If you want to talk giant auditorium speakers as the "standard of 1930's" then we have to compare them to the current giant theater speakers as well.

I think for movies, encoding, amplification and speakers are much better than it used to be. Encoding alone is about 8 generations ahead of what it was then. Single track optical, double track optical, Dolby Surround, multi-track magnetic, Dolby Digital and SMTE locked DTS.  Standards for measurements, calibration and room acoustics have also improved greatly. Mind you, the movies haven't really gotten better though. :)

So apples to apples, yes, things have gotten much better, from stereo to television sound, living room sound, and car audio.

As I've said before though, some critical parts of speaker technology Have improved, but not every manufacturer cares to pay attention. Distortion, compression, thermal compression, and stored energy.  Not everyone cares so not everyone bothers. I do. :)

Best,


Erik

As one who loves my vintage Altec and their horns, I can listen to them until I just can't keep my eyes open any longer, no fatigue from my diy Altecs.
Great sounds, and low cost compared to what I see today.

I can't resist tossing my 2 sense into the fray...*G*

Theory and the math behind remains the same; we measure them better and more precisely now...

Materials and means have improved; 'mass market' offerings have improved, but are subject to 'cost analysis' and ROI, yielding 'meh'.  'High end' has become a garden or a wasteland (depending on your POV) of what's selected and applied and how, yielding endless posts on 'X does what and how better than Y or Z' here @ AG and anywhere else you bide your time.

I'd rather waste my time DIY'ing my Walsh's.  More bang for my buck, IMHO, since I'm faced with either vintage of unknown use/abuse, HHR, or German Physiks.  And I can fix them myself. ;)

Anything really new?  DML's...although I suspect if one digs long enough you'd find something somewhere that would (at least) allude to the concept.  The "we set a loudspeaker face down on this suspended panel and it sounded funny" sort of thing.  Nobody made any $ on it, so they walked away....*L*  Now 'they' are exciting plywood, glass, and composites, tinkering with it.  I'm intrigued...watching for now...

Vintage....hmm, I'm sitting on some '80's JBL 3 ways looking for a box to inhabit.  Cabs were trashed by mindless geeks, reconed the woofers, ready for their 2nd life.  A reconed EV 15" dying to be a New Age sub.  A pair of horn/woofer Utah 2way wanting a home that looks 'cool' (I want the horn visible...so few people have actually heard a horn these days...

What boats my float of late is the 'what if' of combining an array of Walsh, DML, and a distributed bass (DEBRA, if you're inclined to find) and taking over the space with active EQ on all of it.  Purpose build a 'puter to push it all around.  See if imaging can be taken to another level...

*G* Y'all have your 'quests'.  I have mine.  

In terms of new physics or fundamental technologies (as someone pointed out, planar was also from the 1930's), there is nothing new since then for loudspeakers. We are still pushing air to make soundwaves and the method of generating air motion is down to moving diaphragms/membranes/cones.
Where there has been new technology advances is in electronics i.e. amplification via solid state devices and digital technology (both for amplification and source recording/playback). The advances in electronics allow for much greater power to be send to speakers which have allowed for smaller speakers that can more readily fit into modern living space and even automobiles to generate the same or greater SPL (sound pressure level) as large horn speakers of 1930's. Solid state and digital technologies have allowed for miniaturization of components and also reduce costs and ease of mass production to enable the mass public to enjoy high fidelity music. This is where there has been advances. In the 1930's, high fidelity music was limited to the wealthy and the few. 
I myself enjoy low powered SET amps and single driver high efficiency loudspeakers and I do enjoy a good horn speaker and generally prefer them to modern speakers. And in this regard, I don't feel that modern, contemporary loudspeaker systems sound better than the vintage ones that have been setup appropriately ... at least to my ears. FWIW and IMHO.

But it is clear that speaker systems
for concert performances have improved dramatically from the experiences I had in the Boston Garden in the early 70s. Sometimes there was so much distortion it greatly detracted from the enjoyment. Now we mostly hear very clearly at high volumes.