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

   I never knew you invented OTL I assumed it was created in 1954 by Mr Cecil Hall for EV.

Probably a topic for a different thread... the Hall amplifier was not made for EV- but EV did use the Circlotron circuit in their Wiggins amplifiers. There were several other OTL patents issued in the 1950s for various different topologies. My implementation used a Circlotron like the Hall amplifier, but the driver setup is different.

With regards to the driver design: the materials used in my speakers simply were not available in the 1920s. I've heard the same setup using aluminum diaphragms instead of the beryllium with Kapton surround and the difference was pretty obvious. The aluminum had breakups which made it harsh. The first breakup on the Classic Audio diaphragm is at 35KHz so its a lot smoother- its the sort of thing you hear right away- and it can play a lot louder without becoming oppressive. That's a significant improvement in many audiophile's opinion, not just my own.

But as I maintained earlier, the really big improvement is probably the introduction of the Theil/Small parameters, which allow you to design the cabinet and crossover properly for the various drivers without having to build it first.

People like Ed Villchur and Gilbert Briggs knew as much about loudspeakers as anyone around today.

Some of the stories about Briggs live v recording shows are still wonderful.

One thing is indisputable, high quality sound has never been as affordable as now. Hi-Fi for the masses, if they want it. Those ba****ds responsible for the loudness wars have blighted a generation.

Hopefully we are now in a new era where low bit MP3 is a thing of the past.

After receiving a good num of modern state of the art transducers and horns I still stand by my statement that we have not made much progress in sound quality since the early spurt of development during the 1930s even the newest designs I have received have more in common with 1930s tech sure we have modern material tech but many of these modern materials are not better than the old just cheaper to use and do not hold up near as well. I just had a manufacturer send me a FC driver they just developed its near same as an old WE driver just computer optimized. In the 1930s the largest corporations on earth and some of the best minds designed loudspeakers this has not and will not happen again and it's why that tech has held up so well and is basically still in use today.

Yes, unfortunately it looks as if major improvements are a thing of the past. Since the 1930s it’s difficult to think of major breakthroughs.

Maybe only 2 -

1947 Tannoy Dual Concentric by Ronald Rackham

1954 Edgar Villchur invents the acoustic suspension loudspeaker

[1957’s Peter Walker’s Quad Electrostatic is an alternative design but it’s difficult to ever see it attaining the popularity of the moving coil design].

The rest seems to be a case of endless experiment and refinement within certain budgets. Whichever way you look at it loudspeakers remain tremendously inefficient, wasting up to 99% of energy fed in through heat.

Still the search for improvements goes on with different approaches proving that there is still no one set formula for designing a loudspeaker. In fact there’s no clear evidence that even the original cone material (paper) has ever truly been improved upon.

Two recent approaches I am aware of include the Monopulse designs which are distinctly different with their obsessive devotion to timing to merit an audition.

The other is the approach taken by the Ohm Walsh 2000s which are steadily generating a good word of mouth following.

Both, with their alternate approaches may be significant incremental steps forward as opposed to mere refinement or just a reshuffling of sonic priorities.

Whether either will ever demonstrate a clear superiority over existing designs remains yet to be seen.

In fact there’s no clear evidence that even the original cone material (paper) has ever truly been improved upon.

I believe, it is pretty demonstrable, that other materials other than paper, are: lower in resonance, lighter (improving transient response), stiffer (decreased flexing lowering distortion), better magnet materials and coil materials, better damped, and more.

Yes, there are some great paper divers around (SB Acoustics Egyption papyrus mids, for example), but even these have a lot of technology beyond original paper cone materials.

Two recent approaches I am aware of include the Monopulse designs which are distinctly different with their obsessive devotion to timing to merit an audition.

The other is the approach taken by the Ohm Walsh 2000s which are steadily generating a good word of mouth following.

Also, check into bending wave technology, as produced by Goebel speakers. They are pretty impressive, to say the least.