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.

Your TAD drivers all based on early 1920s designs,the horn of the CAR is just a evolution of a 1940s design. OTL amplifier is from the 1950s sure you improved but you didn't create invent.

OTLs: yes I invented my circuit myself. I didn't know about other OTLs at the time. I got two patents- more than anyone else in the field. More on the way.

While the drivers might be loosely based on the prior art, the fact is nothing like them existed or could have existed as early as the dates above. The simple fact is that computer technology has made speakers better- including horn designs.

Horns are simply not the best in terms of accuracy but they do deliver exceptional SPL for little power - great for live music sound reinforcement.

Actually a good horn can be quite accurate- if you think about it, the driver does not have to have a lot of excursion to do its job. If its properly designed, it can be lower distortion as a result. Since the electronics don't have to work as hard to drive the speaker, its also possible for them to be lower distortion too.

My speakers at home are made by Classic Audio Loudspeakers. I may have mentioned this on this thread a long time ago.

They differ from vintage stuff in several ways. First, the midrange driver, which employs a 3" compression driver coupled to a machined maple horn. is different in that the diaphragm is built of beryllium, but using a Kapton surround rather than a metal surround. This extends the bandwidth of the driver and prevents breakups- the first being at 35KHz. It is also field-coil powered. The horn is a new design and does not have the typical peak at the bottom end of the pass band which is caused by an error in design- common in a lot of vintage midrange horns.

So as a result is it faster, smoother and more detailed than vintage midrange horns. People often comment that is sounds like an ESL, but of course its a lot easier to drive and has greater dynamic range.

The woofers are a pair of 15" TAD drivers with Alnico magnets. One of the woofers has a free air resonance at 22Hz. Both drivers can handle 150 watts no worries. They are in series so the speaker can handle 300 watts. I don't think any of the vintage stuff can do that. In addition, the Theil/Small parameters were not understood until the mid 1960s or so- so port openings were a bit of a guess in the vintage stuff. These days computer modeling has the ports spot-on.

The crossovers are 6db with Mundorf silver and gold foil caps. Those parts didn't exist in the vintage days.

The result is overall the speaker is faster, more transparent and has more deep bass than vintage designs (with a sacrifice of some efficiency since the speaker is bass reflex rather than horn loaded).

I like the vintage stuff and if priced right can be nice to play with. But they don't hold up to the new stuff.

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.

Mapman whats missing-  realistic sound quality, the ability to allow listener to feel the emotion of the music. The ability to easily hear the mix ie pick out the individual instruments and vocals along with the added studio work. Realistic image size and dynamic range.The at ease at any SPL the ability to sound wonderful out of sweet spot and through out home. Extreme lack of listening fatigue. A clear real sounding vocal ability the ability to do this all on massively low power. Extreme reliability and ease of service in field by owner. Today most all of this is missing and if present only a small part of it.

I also disagree. Vintage speakers of high efficiency really don't play bass right, they are less detailed and harsher due to breakups in the various drivers and they don't handle power well (are less reliable). So the statement above seems false on all counts.

Atmasphere cant do bass right! Maybe wee ones dont but full sized sure do. Less detailed maybe if you dont add a tweeter keep in mind these designs were only good to 8khz. Dont handle power well! What the heck dude that one boggles my mind its so so wrong come visit so I can prove you wrong on all accounts lol.

Vintage designs have proven there reliability modern has not. Functioning after near 80 years to atmasphere doesn’t show reliability? Then I dont know what standards hes using. Also arent you involved with marketing Classic Audio Reproductions? So maybe as Upton Sinclair said it { “It is difficult to get a man to understand something, when his salary depends on his not understanding it.”}

I often show with Classic Audio Loudspeakers at shows. In that regard I suppose I am 'involved' although John Wolff seems to do pretty well on his own. I show with him because his speakers work, and don't have the faults I previously described.

Johnk, I've had EVs, Klipsch, Altec and JBL. None of them are free of breakups in their drivers (in particular, the midrange drivers) and so they sound harsher and less detailed. I'm used to hearing drivers with no breakups, so I am used to them being smooth. A person might not know what I am talking about if they are not used to such drivers! Under those circumstances, older vintage stuff sounds just fine, but I would not call it state of the art!

Reliability- I've seen plenty of vintage drivers fail for the simple reason that they are old. glue failing, paper rotting, need I go on?? Setting the age aside, how about limited power handling? Or inability to handle excursion? Breakups (those are sought after in guitar speakers but cause harshness and distortion in hifi speakers; breakups in the Altec compression drivers can cause the diaphragm to crack; I've changed a lot of those in my time)? Reduction of cabinet resonance? Cheesy speaker terminals and wiring? These are problems that are solved or reduced in newer designs.

Now there is a reason why vintage stuff is valuable and expensive. Its not always due to performance though. It might simply be because lots of older stuff is cool and there isn't that much of it. I just sold a 1941 Indian motorbike and one would be hard pressed to say that it had anything over modern bikes except style points and it went for a lot more dough than most modern bikes do! And heck, you can still make music with older speakers but you have to deal with their limitations. In particular I like to play music a bit on the loud side and I like electronic music with lots of bass impact....

What does it even mean to "play bass right"?

That's easy! In addition to making amps, I run a recording studio and have done a number of recordings. One of them has the largest bass drum that was in the state of Minnesota at the time of the recording- it was 6 feet in diameter and was something you felt rather than heard, especially when played softly. Most older speakers simply can't reproduce it right- certainly nothing from the 30s can. Now I was there at the recording session since I recorded it... and I have the master tapes and the test pressings of the LP. I **know** what this recording sounds like and its a simple fact that all vintage high efficiency speakers can't play the bass right. Some lower efficiency speakers can, I had Fultons back in the 80s when I did this recording and the Fulton Premieres could do it. But they were not particularly efficient. Today I have speakers in my living room that do the job just fine and they are 98 db.

When you have a recording that you know because you were there when it was made then you have a reference. I do recommend that any audiophile do field recordings when they can and get some idea of how to place microphones and otherwise sort out what the recording process is all about. Its an eye opener. If you can further get that recording onto a format that is easily played (CD or LP for example) then you have a tool for understanding how any system actually sounds.

So to play bass right, the system has to be able to simultaneously have the extension into the low 20s, the ability to play it with impact and the nuance to do the subtle passages without loosing information.

The Theile/Small parameters (https://en.wikipedia.org/wiki/Thiele/Small) were not worked out until sometime in the early 1960s and 70s; what this means is that not many speakers before that time could have had the bass sections of their cabinets properly designed. Its pretty well known for example that the Altec A7 'Voice of the Theater' didn't have the port set up right. Being that's the case, the argument that bass is somehow 'right' in the prior art falls apart pretty quick.

EVs, Klipsch, Altec and JBL all are not 1930s. The Altec A7 you use as a example of poor bass its again not a 1930s design but is a affordable down sized design so expecting that to have deep bass and to be a example of design faults from the 1930s is very off. And you say this- Most older speakers simply can’t reproduce it right- certainly nothing from the 30s can- again since you admit no experience with 1930s how can you say such a all encompassing thing. Your argument about old wiring well I see cloths back in and costly as all heck and noted more than a few modern builders that are using screw type connections and bakelite. And you mention a 98db loudspeaker that good to 20hz I would like to see that since Hoffmans iron law it would have to be giant. So thanks for replying etc but you haven't changed my mind.

OK- so 50s tech is out- the gist I'm getting here is that for you the 1930s was the pinnacle of loudspeaker technology? Is that a fair statement?

Could you point out the spot where I admit to no experience with 30's loudspeakers? I don't think that is correct. Like Al, I've done lots of restoration of older pre-war radios, some of which were rather sophisticated, in particular several large Zeniths (our Novacron amp takes its design aesthetic from a pre-war Zenith) and an Allwave Scott. I've also had exposure to older Western Electric- the large 'Ramhorn' system (there's a set here in the Twin Cities), and at the Munich show there has been for several years a Western Electric system running in a large room that featured 13A horns. I thought it was one of the better sounding rooms at the show- when it was working (one day when I auditioned it one channel was weak).

But one thing that system simple could not do (despite the very large Altec subs) was play deep bass, although the Altec did sound quite nice.

If you want to see the speakers that go to 20Hz, the speaker I have is a custom T-3 made by Classic Audio Loudspeakers. Normally they cut off at 22Hz but I had my cabinets made a bit larger so they would go to 20Hz. They are the size of a mid-sized refrigerator, about 5 1/2 feet high and employ a pair of 15" high-excursion woofers port-loaded. 

That speaker employs a field-coil powered midrange that uses a 3" beryllium diaphragm which in turn has a Kapton surround. This technology did not exist even 30 years ago let alone the 1930s (although field coils were the only game in town back then)! The Kapton surround keeps the diaphragm from cracking and failing and reduces artifacts brought on by low frequencies. The speaker uses a 6db slope crossed over at 500Hz so this is rather important! Because the diaphragm is lighter and has no breakups, it is smoother and more detailed than compression drivers that don't use the same technology, which is to say: all drivers made in the 1930s.   Since the field coil has to be powered by a power supply, the power supply is thus part of the improvement: technology that simply didn't exist back in the 1930s. I know these days a lot of people go for Tungar rectifiers (which by all accounts seem to introduce hum). I have a box of them sitting in my office. The hum comes from the simple fact that the power supply can't be properly bypassed (without damaging the Tungar). This means that a certain amount of intermodulation with the hum frequency is impossible to avoid. That's a coloration. You might like it, but there is no way its more accurate!

So..it appears that John is right, there is no innovation in a true meaning of it, just some improvements in certain areas, maybe.
Speaking of cars, not from 30s. The original BMW M3, small and light, was a true driver's car. The same with Porsche. Now look at those modern computers on wheels that those cars have become. I don't need them.

I used to run a Ford Bronco, because I could load my hang glider on it and get to the top of any mountain that had a road up it. It had no computers and was easy to service, being very simple.

I replaced it with an Expedition, which has about the same cargo area. Despite having an automatic (the Bronco had a 5-speed overdrive transmission), the Expedition accelerates faster, due to having about twice the power, handles better, is very quiet inside, is also much more comfortable and despite the computer is a lot more reliable and just does not need the service all the time like the Bronco did. On top of all that, it gets about 3 mpg better mileage. That is a difference that was wrought in the space of about 25 years.

The funny thing is, the basic designs of the two are really similar.

This is true of speakers too. But if one ignores the effect that materials science has had on speakers one might likely throw out the baby with the bath. Kapton didn't exist 70 years ago. Neither did highly regulated power supplies. The impact of the Theile/Small parameters can't be ignored.

If I were to point to one thing that has really affect high end audio in the last 30 years its how we manage vibration. Speaker cabinets are much more dead now; literally that's the big improvement in most turntables, and killing breakup in drivers is still a pretty big deal.

I like the older designs but there's not a one of them that won't break up.

Its up to the individual to ascertain how important these improvements are. For my own part, I appreciate the size and efficiency as well as the refinement offered by the new technology that simply isn't there in older designs. 

But I make my own recordings. I know what they sound like...

^^ you are better at this than I. That is what I was trying to say for all that text.

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.

According to the same website that speaks of the Shearer loudspeaker the Voice of the Theater was an improvement over the earlier design (http://www.audioheritage.org/html/profiles/altec/vott.htm). The reasons why and what was done are outlined at that link.

Johnk, do you feel this is not the case- do you feel that the Shearer was a better system? If so, why (do you think something was lost with the succeeding design)?

With regards to the Shearer, while solving a lot of problems of the prior art in its day, it also had problems of its own. Many of these were addressed in the Altec VOTT designs. And they were pretty well universally acknowledged as improvements.

I ran VOTTs for a number of years. Then a friend lent me a set of FMI 80s. We set them up in the same place as occupied by the VOTTs and the improvement in imaging, nuance and bass impact was immediately apparent. Mind you, the FMI80 was a simple 2-way bookshelf speaker with an 8" woofer. The one thing that they could not do better was high volume, which one would expect.

These days the speakers I play have far more resolution than those FMI80s, far more bandwidth too, yet the efficiency is up at 98 db, allowing for that sense of power and air that you only get when the amp does not have to work for a living. So I see that as a huge improvement over the VOTTs, which were allegedly (as seen on the JBL/Altec site linked in the opening post) better than the Shearers. Now, if logic is still something you can use, that must mean that my speakers sound better in nearly every way than the Shearers. My speakers BTW are the Classic Audio Loudspeaker project T-3.2, equipped with the field coil midrange drivers. They are not the best that Classic makes, but they do fit in my room which is a plus (the T-1s do not).

I get the romantic experience that is part of the vintage scene. That romance is not just in audio; I love to ride a vintage motorbike or bicycle as well. Such things often have a certain charm. But that charm is only available through experience, regardless of the measurements.

Great article by Art Dudley in October Stereophile. He comes down squarely on the side of the best vintage speakers not having been surpassed or even equalled by modern speakers.

What is meant by 'the best vintage speakers'? old Quads? Hartsfields? AR-1s?