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
Convert?fit=crop&h=128&rotate=exif&w=128johnk
Love it.
Will it fit in my listening room...?🤔

Sure! Fits fine in mine and my 1/2 lansing 18w5 fits even in my office for near field use  http://www.audioheritage.org/images/lmco/photos/products/shearer/shearer2.jpg
1930s the largest corps in the world spent significant resources on loudspeaker development. Today very small corps invest small sums reinventing much of what was designed then.
Great progress for sure.

Fabulous. Unfortunately, many of the vintage horn systems are expensive, but compared to the cost of some uber gear today, may not be so crazy. I went to a modern horn/SET implementation a decade ago. I'm intrigued by the vintage stuff. 
Hi John,
    I assume that you started this thread for the sake of discussion, you know the drill as much as anyone.... So, I'm not going deeply to leave room for discussion out there....  As you know math is math. That and how a loudspeaker works hasn't changed.  What has changed is manufacturing technics,  manufacturing tolerances, materials Used (Neo magnets, cast basket materials, cone materials, crossover parts etc.)  Designs have improved some, (underhung magnets Domes, Ribbons and plenty of other things) .... So, plenty of improvements, but that doesn't mean that there weren't some  very good things produced through the years.  Every old speaker out there that I have worked on, I have been able to improve upon in some way with modern crossover parts or dampening material or coating a driver etc.
Hello and thxs for replying. The dome was used in FC compression drivers in the 1920s Walter H. Schottky developed the very first ribbon loudspeaker that used diodes about 1925. Wool tar lead cork rubber high mass all were used back in the 1930s and are still considered advanced today and you will find those materials in some of the most costly designs today. As far as rare earths while very high gauss for size they mostly are aranged in arrays and have little mass, since most transducers today that use such are designed for high power this reduced mass over alnico or ferrites can cause thermal compression. This causes listening fatigue why many systems sound great for 30-40 mins then you had enough.
Of course there's been progress, to deny it is foolish.  The manufacturing process allows larger quantities to be made at a lower cost than was possible 75 years ago.  That said, the best designs from that period are marvels of design/technology and sound amazing.  But to use a motorcycle analogy, nobody uses a Vincent Black Shadow as their everyday ride.
It seems that the primary objective during the area of classic vintage speakers was efficiency,   faithful reproduction of human voice and acoustic instruments. Current emphasis seems to be accommodating high power amplifiers and ultra level  detail and resolution. The resultant sound character  reflects the different philosophical approaches. 
Charles, 
In terms of performance vintage speakers have stood the test of time far more so than motorcycles. That analogy doesn't work for me. Much larger gap between old vs modern motorcycles. 😊
Charles, 
Thanks johnk for the link in your OP.  It led me to information I didn't know about the Hartsfield, probably the third super speaker system I encountered as a kid after the Electro Voice Patrician and Bozak Concert Grand in the early 50's.  Can anyone imagine using a Paragon as a center speaker flanked by a pair of Hartsfields as was the original intention?  There were a number of new "HiFi" shops in the area that a Venice canal rat like me could haunt -- in retrospect, I don't understand why they were always so accommodating.  My 90's-era KEF Reference 107/2s continue to amaze me.
Most speakers I find interesting are out of my price range. If I had 10k to drop I would spend a lil less and grab a set of ATC SCM40 v2.
My bud has these with a Krell Vanguard, they are so precise it's unreal. To think he is just entry level and gets the sound he has makes me weep. I need a raise, G'damn it...lmfao
More sound out of smaller boxes. But only with more power. Also many new transducer technologies and innovations since then.  Probably also way more really good ones to choose from  with unique strengths and weaknesses. 

Are they better?     Not sure there is a ton of difference between the best then or now.   Lots of advance in the source devices and amplifiers feeding them though. 
" More sound out of smaller boxes" is a great advancement.
The horn speakers. There are many who won't listen to them, either vintage or modern.
I assume we're talking about home audio speakers.   

Sound overall all at large outdoor concert venues has increased greatly.   So better things seem possible at the largest scale.   


Most home home listening rooms aren't any larger today than years ago so not as great a challenge to max out what can be done there.  
ESL's. Walker's originals were very musical, but today's ESL's are cleaner, more dynamic, with an extra octave top and bottom. Magnepans are another innovation. Especially with cost-no-object aftermarket parts.

What about MBL?

Well, efficiency without resorting to an electromagnet based speaker is one big issue compared to that design! :) Unplug them from the wall outlet and they are mute.

Horns themselves have improved quite a bit in terms of distortion, extension and coverage.  I don't care how good those sounded, I have no place for them in my house.

But, are we talking home speakers or professional speakers?  It's unfair to compare one to the other.

In particular, one big benefit a lot of well made auditorium size speakers still have is lack of compression, and especially thermally related compression, than their consumer counterparts.

BUT!! Here's another way to look at it. Find me a speaker from the 1930's that occupied no more than 2 square feet of floor space that sounds anywhere near as good as a current pair of Monitor Audio Silver floor standers.


No by moving away from high efficiency we have been moving backwards. 
There's no doubt that large theatre horn systems from the '30s are impractical for most homes. And many of the improvements cited have to do with smaller size to accommodate a home environment. (I remember early implementations of Villichur's acoustic suspension design, and they always sounded "wooly" and thick to my ears, even with powerful amplifiers). But, there is something magical about the combination of high quality horns and SET- an immediacy and "in the room" quality that is not squawky or ear-bleeding. 
Horns, at least in the States, were given short shrift by the hi-fi commentariat, and except for modern implementations (Avantgarde, Cessaro, Acapella) are still largely ignored as "fringe." (I think Art Dudley explores older horn gear, but I'm no longer a regular reader of hi-fi magazines). 
The biggest drawback I have found--using a modern implementation (Avantgarde) is the discontinuity between the horn midrange and dynamic woofers. The thing I like about them is the absence of any crossover on the midhorn. This helps, I think, give that speaker a quality that sounds less "reproduced." 
Interestingly, within the "fringe," field coils have made a comeback. 
No doubt these speakers and their more modern reinterpretations have their shortcomings. But, when I hear a big state of the art dynamic speaker system with multiple ranges of drivers, driven by large power amps, I also hear shortcomings- a loss of immediacy and inability to render musical "detail" at low output levels. 
I'm not advocating one school or another as "better"-anybody who has spent time around this stuff knows that there are firmly entrenched views based on listener experience and preference that I won't question. And, it's all trade-offs, isn't it? One strength gained in exchange for another weakness.
I was an electrostat (Quad) listener for many decades, and lived with the shortcomings of the original Quad (a/k/a the '57) because of the purity of the midrange despite the speaker's enormous limitations. That was a tradeoff I was willing to make for a long time.
Interesting comment from Terry9 that electrostats have improved too- but in sound quality or practical useability? I still have an old pair of Crosby-modded '63's and while they were a "better" speaker overall in terms of range, dynamic ability and size of image, I didn't think they had the magic of the original Quad in the midrange. Trying to get the '57 to work with ribbon tweeters and subwoofers at the time was a mess of incoherency-a glorious mess, but not something I could live with- I chose to listen to the Quads straight up, without supplementation of the bass or high frequencies.
Sometimes, I think of the analogies to the automobile (i know it is a cliche in hi-fi to make this comparison but...). A modern car is better in every way than a pre-war car. Size, acceleration, stopping, handling, practicality, reliability and ready availability of parts. But, there's something profound about the experience of driving one of the old sports cars that connects you with the road like nothing else.  I find the immediacy and visceral quality of horns to be very compelling and despite their size, they seem to get out of the way of the music. I'm no doubt within that segment of listeners that appreciates these things for their positives and is willing to ignore their limitations. 

Electrostatics and planars are all 1930s inventions. And for others small to me that sounds worse than many 1930s designs isn't a advancement in sound quality but a advancement in convenience  and  cost cutting etc. Think a few have missed my point and keep pointing to what they think is a modern idea but was created in the 1920-30s 
MBL are ribbons well designed ribbons but ribbon techs near a 100 years old
Johnk, by that standard there has been no improvement in wireless communication since Marconi in 1895?  Just because something was invented doesn't mean it
Walsh drivers were conceived and realized in the 1960s.   

Hi John,

      Even though what you post is correct. The arguments that you make are really out of context compared to the title of the thread that you have created... Yes, there has been huge advancements.  Yes the dome was invented around 1925, most of the technologies that we use were created between 1925 and 1930.

The Rice and Kellogg patents for the dome that your reference do not show a rim-driven, direct-radiator device designed for high frequencies, it wasn't until the late 1950's that the dome anywhere near how we know it started being used.... Rice and Kellogg experimented widely with all types of transducers.

There are too many to name above, but some excellent points made about advancements.  Maybe I mis took the original point. 

One of the best speakers that I had ever heard ... at least in high frequencies was the Hill Plasmatronic.  Not sure is Hill designed the plasma driver or if it was from the early days,  but there is a technology that I personally haven't seen before or since.

http://www.cnet.com/news/forty-years-ago-the-ohm-f-speaker-was-a-game-changer-it-still-is/

The modern day descendants of these continue to improve regularly as well.  

Definite game changers for me. 
The Acapella line includes a plasma tweeter, not sure what relation it bears to the Plasmatronic. (<What a great name).
@mapman  Really great memories of Ohm Fs. They were my first real audiophile speakers. I was just out of high school and $900 was a fortune then, but I had to have them. And I knew they were the best speakers in the world because Julian Hirsch told me so ;) The good old days.
The plasma driver can be traced to 1900 and William Duddles singing arc The point I tried and failed to make is were is the modern equivalent in invention of something new not just refinement of very old tech to a the ribbon, dynamic, planar, electrostatic, plasma etc. Sure we have the 1950s bending wave transducer like Manger but I feel as far as design advancement we have greatly stagnated since the early spurt in designing for audio use. Pro or in home.
I think in many fields it's been 80+ years of refinement and not much totally new invention...
but the new stuff, to me, sure is a lot better
Whart, you raise interesting points. As for the Quads, I have the new ones, highly modified.

Your experience mirrors mine in that the Quad 57’s sounded very good. What prevents the successors from sounding as musical is, in no particular order:
- step up transformers
- overpower protection circuits
- high dielectric constant ceramic caps in the delay line

But they have wonderful bones - the basics are there!!!

So, what I did was:
- change step ups to a Vanderveen toroidal design
- built power amps which had V+ / V- rails which could not drive the new step up transformers into the protection range, and so could safely by-pass the protection circuits
- daisy-chained aftermarket styrene caps to replace some ceramic caps, and built teflon caps to replace the others
- bought multiple pairs of speakers.

The result is that each speaker:
- has clean electronics
- is minimally driven
- and sounds glorious, from ppp to FFF.

I have played the system loud enough for the hearing challenged, on a few occasions. Volume is not realistically limited above 40Hz. So, for all practical purposes, volume is not an issue. Multiple speakers solves that.

Getting back to the OP:

Note that teflon caps were not available in 1930. The compound was not discovered until 1938. Applications took longer.

Transistors (hence low voltage circuits) were not available until the 50’s, and no-one knew how to use full complementary push-pull until at least a generation later. Not that many appear to know today, for that matter.
Another new thing - laser trimmed resistors. Can be made accurate to a few ppm. The new (dare I say it?) Vishay VAR series is in a sonic class by itself.
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.
Yes and no.  It would be very difficult to find whole speaker systems, and even modern speakers using vintage drivers, that would make compact monitors that sound as good as modern monitor speakers.  The same probably holds true for thin column-type floorstanding speakers.

But, for systems where one is not constrained by practical considerations, such as size and ugliness, I would go with a modern system built with vintage or replica vintage drivers over anything I've heard from modern speakers.  If size and cost is not an issue, something with Jensen M-18 fieldcoil woofers and Western Electric 555 drivers and 15A horn and 597 tweeter would be nice to have (and a room big enough for such a system would be really nice).  For a "compact" system, something with the Jensen/ERPI M-13 fieldcoil and a 597 tweeter would also be a nice choice.  I also happen to like my system which is built around the Western Electric 713b midrange compression driver (made sometime around 1939).

At the Capital Audiofest, held this past weekend, Deja Vu Audio was showing a recently-built speaker featuring vintage drivers.  The speakers had 15" Jensen woofers and midrange compression drivers from Yoshimura Labs (a 1960-70's Japanese company that made theater/public address systems that emulated Western Electric drivers) in an open baffle configuration (it looked like a box with a closed back, but the back allowed sound to pass through).  It is hard to beat this type of system for delivering harmonic "denseness" (rich, saturated sound) and a relaxed (not edgy) and natural presentation while also delivering terrific dynamics, speed and clarity.

The BIG plus with many vintage systems is that they can be run with a wide array of low-powered amps.  To me, the best sound is delivered by lower powered amps, regardless of whether one goes with tubes or solid state.
As usual LarryI has a balanced and measured post which means I agree with him.  There is no question that modern speaker design software and measurement tools have contributed to an overall improvement in speaker sound quality.  For those of us who were kicking tires in hifi stores in the 1960s and each decade since, I can say that there are fewer poor sounding speakers today than in years past.  This is especially true with lower price speakers and smaller speakers. 

But if we ignore price and size considerations, the very best vintage drivers and horns have some special musical qualities that are not equaled by today's speakers at any price.  I have only limited experience with the big Western Electric horns (and no experience at all with the Shearer horns mentioned by the OP) but each time I have heard them left no doubt they are capable of excellent sound quality.  On a much more accessible level, I find that my own speakers using a vintage 15" Jensen paper cone woofer and Altec 32A horn with 802-8G compression driver (dating probably from the 1970s) are very satisfying musically. 
Sal,
Yes, Larryi comments are consistently insightful and well-thought-out.  Larryi in general I agree with you preference for the lower power amplifiers in regard to superior sound quality. This point is driven home often when I hear the mega power amplifiers driving difficult load/inefficient speakers. 
Charles, 
Regarding Thiel loudspeakers, I certainly hope so. Happy Listening!
The Theil-Small parameters is something that has changed! It makes predicting the performance of a driver in a box possible. Prior to these specs, sorting out the right size for a port opening in a box was experience and guesswork. This has lead to wider range loudspeakers with less coloration.

Another thing that has improved is horn design. Its now possible to optimize in a way that was not 50 or 80 years ago. There are also improved materials for compression drivers, so its possible to build smoother sounding more detailed horns. My speakers at home benefit from this- the first breakup in the midrange horn is at about 35KHz. So it has the speed and detail of an ESL.


 It led me to information I didn't know about the Hartsfield, probably the third super speaker system I encountered as a kid after the Electro Voice Patrician and Bozak Concert Grand in the early 50's.

Classic Audio Loudspeakers has been making a Harsfield reproduction since the mid-1980s. The proprietor, John Wolff, has improved the detail and bandwidth by using materials and drivers that did not exist in the 1950s. They play bass much better than the originals! They are smoother and more detailed as well as being more efficient (I'm sure the field coil drivers he uses are part of that).

Its a simple fact that loudspeaker technology is significantly advanced over what was around even 30 years ago. Materials and modeling have gotten better and I expect that will continue.

I think the bottom line is loudspeaker technology has improved considerably over the years as is the case with most any active technology over time and that there is more possible today than ever before and many more choices for top notch performance case by case than ever before as well.

Has the best possible end result sound in most home audio cases improved?

Probably somewhat but the technology to solve the problem effectively has been around for many years in one form or another.

I am convinced also that source gear and amplifier technology has improved vastly in all regards over the same timeframe meaning the speaker technology applied, old or new, sounds better than ever.

My personal experience with the evolution of loudspeakers don’t extend for longer than back to the late 70’s, and though this mayn’t warrant calling these earlier encounters vintage speakers per se, there’s definitely been a tendency of speakers being progressively smaller (and then perhaps bigger again). As an example back in the late 80’s a pair of JBL 250Ti’s could be had for roughly $3,500 (following a decline in the exchange rate of the Dollar), and though you could arguably have a different, more "hifi-ish" sound for that amount of money (or even less), what you got was a big, versatile, high quality visceral sound, and two lovely pieces of furniture to boot. The JBL 250TI Jubilee’s could be had for about a $1,000 more a pair a little over a decade later, a fine value as well (as I see it).
I like seeing JBL go back to the use of compression drivers in tandem with bigger 15" bass/mid drives for the last decade or so with their "commercial" and monitor series (except of course the Everest’s/K2, which have been more or less less true to their heritage line), but the price for these, even where no real veneer was used, was/is steep, and a reflection of something other than inflation alone; the market sees a progressive use of smaller speakers that are refined into being quite expensive, and their bigger iterations are of course priced accordingly (i.e.: very expensive). Big, visceral sound is a quality in itself, I find, and a very important parameter in making you give-in to the music as something other than reproduced. It’s a shame then that where this is to be attained the price may be out of reach or requiring extra monetary priorities, if the desired size of the speakers is even to be had.
The main problem, to my ears, is the almost exclusive reliance on the direct radiating principle, as this generally shortchanges size (i.e.: radiation area) and not least sensitivity (the latter of which excludes the use of smaller-watts amps). I’ve no doubt that speaker technology has advanced significantly over the years, but its application into actual designs is hampered by before mentioned.
Perhaps an analogy to imagery is in place: seeing 2K or 4K films (or most any viable resolution, for that matter) on screens below 50-60" seems not to immerge you in the visuals as effectively as could. It is said that for the eyes and mind to properly exclude visual information not created by the screen itself, a particular minimum ratio of the distance to the screen in relation to its size is required (which generally equates to some +80-90" for home use). This way your eyes (and mind) can relax more effectively in the imagery, and hereby exclude the surrounding "noise" that is the environment of the room. Not only that; the effective resolution, certainly with 2K and not least 4K, cannot be taken advantage of unless the screen extends or certain size (again, in relation to the distance to the screen).
In a sense this extends to speakers as well: smaller speakers, highly refined and resolving, can’t seem to "unfold" the proper image in all its glory, but remains instead a minimized presentation of an event, and hereby too obviously reproduced. To me, one major parameter in sound reproduction is size, and I’d rather have that poorly resolved than a smaller ditto highly resolved. Combine the two, size and resolution, and we’re talking.
Added to that is the by-product of high sensitivity, which is not so much about max SPL per se (more like headroom), but the difficult-to-articulated sense of ease. It usually also incorporates the quality of low level resolution, which is an added (and very important) bonus to the ability to play insanely loud (not that that’s needed, but it’s an integral part of named "ease" and versatility).
Modern speakers are no doubt more refined, resolved, airy, and in a sense less colored, but it comes at the expense of a generally minimized presentation, and one that also plays too thinly or even malnourished (both of which could be called coloration as well, by virtue of absence). If the advance in technology were to be applicated with older designs of bigger size and higher sensitivity, I’d feel we could be talking about overall advancement. Thankfully there’s a wide range of speakers to choose among, and so the advancement may be had "locally."
Who among us has heard one or more loudspeakers from the 30's?

 I started with modern dabbled in vintage. I wanted to understand the past and learn more about loudspeaker design by exploring the past. I never went into collecting vintage with the mindset that it was better only that it was interesting. I would use my audiophile systems as mains and mostly ended up listening alone. The Shearers my Lansings and WE 13As even my Racon in mono make people dance sound more like real music. I have loudspeakers about from much of the history of cinema and many other famous home designs. I also have some of the most modern. My personal hands on experience with designing manufacturing, collecting, restoring, studying loudspeakers and loudspeaker design made me ponder the ? And I honestly still think we have lost much of the ability to innovate and are more just evolving loudspeaker tech. And much of what the past did so so well has been forgotten..
John what exactly has been forgotten?
We keep perfecting the wheel too. Once something basic is discovered, it's discovered.
But, yeah, the spirit of creativity is down everywhere. Rudimentary computer digital times. Sucks.
I don't think we have lost the ability to innovate- the goals and priorities are different. When those magnificent early theatre sound systems were designed, they were addressing the needs of an entire industry transitioning to the "talkies" and trying to accommodate the space limitations of existing theaters. But, the resources were there and the top companies were competing to develop product. 
Today, look at big data- the ability to collect and analyze massive amounts of data and apply it- to everything from serving targeted advertising to national security- is where the action is, and there are no doubt innovations in that field.  The trickle down to consumer level products- in the form of "smart" phones and appliances, as well as interfaces that are guided by past user selections is what we get, not necessarily better audio. (Though things like DSP have made woofer set up for modest home theatres pretty easy).
Materials science and acoustic models (aided by computers) may have improved, but some of the materials- copper in field coil speakers- mercury vapor tubes, or even the materials and tooling for most vacuum tubes are expensive or hazardous or obsolete. (Look at what happened during the "vinyl boom"- suddenly there was a need for record presses-and none had been made for years; now, those presses have been salvaged, rehab'd and new ones are being built simply because there is demand).   
I'm fascinated by the early days of audio. I'd love to see and hear your private museum at some point John. 
One book worth reading although it isn't strictly technical, and has some gaps- is Cowboys and Indies. Dumb title, but it is essentially the history of reproduced sound and the emergence of the industries and businesses that depended on it (music publishing, record companies and trends in listening behaviors from the 19th century to date). In the process, there is some discussion of the changes in audio technology and how that related to cultural changes at the time. 

Innovation in any field addresses the changing needs or wants of the times.

I like quality old stuff as much as the next guy but there are good reasons why things are the way they are.   Lack of innovation is not one of them.