Jeep Street Comanche Registry


If you're into vintage audio, sound engineering, or American history this article covers them all!


A Tale of Two Speakers

..with apologies to Dickens...

A rambling narrative regarding the history of Altec 836A model loudspeakers.

"The Lido"

I just kind of stumbled into researching the Lido after my sister passed along to me these old speakers that had been our fathers. I remembered him having them over many years, from the time I was about 6 onward. So I took them and put them on the workbench and used them in conjunction with some other unused audio gear I had on-hand and put together a garage audio system. But frankly they didn't sound very good. So I pulled them out of service and set them aside thinking I'd find some new drivers to put in them and refinish the cabinets. And as I thought about them, I was pretty sure I remembered my brother telling me that he may have had to replace one or more of the drivers in the past. And thus the seed was planted.

I started searching the web off and on pursuing specifications for Altec OEM driver replacements initially. The more I learned the more intrigued I became. The reading prompted me to open up the cabinets to see what I actually had and I found myself drawn into a tale of two speakers....

Over the years I had come to appreciate that my dad had a shrewd ear for audio. He didn't always spend tons of money on gear. But his systems always sounded really good. How could I NOT be impressed? I was a young male child with a father that liked listening to loud music! So I grew up sharing his thirst for and enjoyment of great sounding audio components and now with researching the Lido, I've come to wonder if even he knew just how shrewd his ear really was.

Seeing as they are sound reproduction devices, it's ironic that the tale of the Lido really begins long before recorded music was even common. In fact, we need to look back as far as 1869 and make a somewhat superficial examination of the history of the iconic Western Electric Corporation to really understand why these 50 year old speakers would still be so coveted.

Western Electric started essentially as a supplier to inventors. In pursuit of products and technologies related to the telegraph among other things, the company grew by leaps and bounds. Even as far back as the 1876 Centennial Exposition, Western Electric was earning acclaim for its inventions, taking home 5 Gold Medals. It just so happened that this was also the year that Alexander Graham Bell patented his “telephonic” contraption, eventually going head-to-head with one of the largest, most well-funded companies in the U.S. at the time, Western Union.

As the 1870s rolled over into the 1880's, years of hard fought battles and complicated legal wrangling between Bell Telephone, American Union Telegraph, and Western Union culminated in the creation of the American Bell Telephone company.

During all those years Western Electric courted and manufactured for all  these companies and was growing swiftly to become a titan of industry. American Bell Telephone would take various forms as the years went by including being known as American Telephone and Telegraph  or AT&T, a name we know still today..

American Bell Telephone's dramatic growth created a strong need to secure a manufacturer with the resources to make large volumes of quality parts. In 1881, in pursuit of that goal, they were able via stock acquisition to gain a controlling interest in Western Electric, by then the largest and most prestigious electrical manufacturer in the United States.

Within a year after gaining control, Western Electric became the exclusive manufacturer for American Bell Telephone. Research and development of the telephone and related technologies began in earnest.  By 1914 the sophisticated engineers at Western Electric had perfected the first high-vacuum amplifier tube. That tube provided the means by which Bell could extend telephone lines from coast to coast and indeed across the Atlantic by 1927. Bell Lab's high-vacuum tube device was essentially the beginning of the electronic age, revolutionizing communications and making possible radio, television, public address systems and movies with sound!

The Roaring 20's were truly the best of times. The Cotton Club was packed with jazz patrons in full swing and Bessie Smith was singing the blues. Henry Ford was mass producing automobiles and Gershwin, Astaire, Crosby and Valentino entertained the masses with silent movies, song, dance, and theater, all drawing strong audiences. America's fascination with technology was on a high rolling boil and Western Electric was right in the center of the action in many ways. But in October of 1929, it all came crashing down on most Americans. The “best of times” were over and the follow on years of the 1930s were just as truly the worst of times for many in the United States.

Now looking for inexpensive ways to entertain themselves, the largest part of America turned to home-based entertainment, playing parlor games, board games and for those who could afford one, listening to the radio. And although Western Electric had literally revolutionized the theater and movie industry with amplified sound, most families were destitute. Even though there was strong interest, a great many people just could not afford movies and theater. As numbers dwindled at the box office, so did profits for the behemoth Western Electric. By 1936 economic devastation was pervasive and even the largest of companies had to cut costs. So Western Electric determined that they would dissolve the Electrical Research Products group, as a cost cutting measure. But as Western was moving to divest itself of it's motion picture service organization, those who worked in that group had other ideas. Though the economy was in shambles, hopes and dreams were not, and entrepreneurial spirit flickered yet in a few key players.

Resolute that they should keep the development of theater and movie sound systems alive, in 1937 Altec (All Technical Service Co.) was born. Initially and primarily the intent of these determined souls at Altec was simply to continue service and maintenance of Western Electric theater sound equipment. But as the business started and grew, the group decided that they should also pursue the goal of developing new systems as well. And just as Bell did in the early years, they knew they were going to need competent manufacturing facilities to do so.

Four years later, to resolve that need, Altec purchased a struggling speaker company called Lansing Manufacturing Co. in Los Angeles. And thus was born, Altec Lansing.

As were so many, Jim Lansing's company had been in financial trouble and was nearly bankrupt. But they produced what were considered by many to be the best theater sound systems available. Consequently Altec gained more than just a competent manufacturing operation. That acquisition provided truly outstanding production facilities and excellent design work already in progress at Lansing, which formed the basis for many of Altec Lansing's later systems.

As the 40's progressed, Altec Lansing flourished with military contracts which helped them develop a diverse set of products. As well, radio, Hollywood, and theater helped propel amplified sound technology  forward in earnest. As amplified sound and loudspeaker production became more well-developed large halls, churches, and auditoriums provided the stimulus for even more improvements and ever larger-scale public address and sound systems. High quality, life-like sound was more and more in demand and Altec Lansing delivered.

By 1945 the first home loudspeakers and amplifiers were also being produced. This too was the year that he infamous Voice of the Theater commercial speaker system was released. These very highly regarded speaker systems became the system of choice in the most renowned concert halls, cathedrals, and theaters around the world.

But of all the things Western Electric manufactured in the 40's, of  specific interest to us here is this particularly stellar example of engineering prowess: The model 755a loudspeaker.





The 755a was introduced in 1947. It is an 8” full range speaker, meaning it covers lower as well as upper frequencies of the audible (to humans) sound spectrum. In the early years, this driver was found most commonly in train stations, business PA systems, recording studios, and radio stations where they were used as broadcast monitors.

A somewhat lowly beginning for this now-coveted driver.

Some readers will remember seeing the silver cases shown in the image on the left hanging from walls and ceilings in train stations, government buildings, bus stations, and other commercial buildings “back in the day”. These familiar housings most commonly contained a 755 full range speaker.

I have learned that this driver has the remarkable distinction of being what is called nearly “flat” in its response over its designed frequency range of 70-13000Hz. Most speakers will have better response at one end or the other of their range or respond differently at various frequencies within their range.

Not so the 755a.

It can really not be over-stated how amazing this feat was in those very early days when development of these types of products was still in its infancy. Indeed the design specification and quality control exhibited in production point out clearly that Western Electric was actively trying to design the very BEST loudspeaker possible. After all, they intended to market these speakers through their own Graybar subsidiary. They were their own customer and of course wanted the best product possible. I suspect that manufacturing parts for the military contributed significantly to a culture of quality at Western. With the company being a significant government / military contractor for many years and military specifications being what they are, building the highest quality components likely became the everyday way of doing business.

The 755a speaker featured a large AlNiCo magnet and a relatively large voice coil compared to other speakers of the time. Walt Bender, the former publisher of Audiomart and an expert in vintage American audio, has been quoted as saying that the process of creating the cones for these drivers was very intensive. The specially curved, vacuum-formed paper cone reportedly contained silk and cotton components. This special cone also cast a fairly narrow concentration of sound (approx. 70 degrees) allowing very focused sound reproduction.

This cone material and its design characteristics are what give the 755a its heralded clarity and accuracy.

Now, by the late 1930's Western Electric had become HUGE. So much so that the US government had begun to push Western to divest itself of some of its business units by filing anti-trust lawsuits. Some feel it was this +/- 20 years of constant interference by the government in the giant manufacturer's business that was responsible for creating the conditions under which the Electronic Products Group had to be spun off. Others would argue that Western brought the continual harassment upon themselves however, as they held a majority share of the theater sound business throughout the 1930s and often acted as a tyrannical monopoly as the years progressed. Either way, governmental intrusions continued into the 1950's when they  essentially forced Western Electric to stop manufacturing nearly anything related to the theater sound industry.

Some audiophiles, considering the quality of commonly available loudspeakers today, have wondered how much better products might be had Western Electric had been left alone to innovate and manufacture without intrusion.

In any case, in 1950 production of the 755a was passed to Altec and they continued manufacturing the “Western Electric” 755a through 1953. Construction details were altered under Altec's watch, so if labels are missing, details such as the number of welds will reveal the manufacturer. Western Electric originals have six small welds around the bell, while drivers with three welds are Altec manufactured. Also telling is that the Western Electric drivers have four or five different stamps on the gasket, indicating the various and stringent quality control processes that they were subjected to during manufacture. (see image above) While quality control was definitely a primary focus, the Altec versions will have only one or two stamps. The color of the driver can also reveal something about its manufacturing dates and who the manufacturer was.

It has also been noted that some 755a drivers have been observed bearing no Altec or Western Electric logos, labels or markers at all, only a stamped “KS14703”. The KS stands for Kearney Specification. The Kearny Works plant in Kearny, New Jersey was one of the “full plants” for Western Electric, meaning they manufactured a wide range of products. Drivers bearing this mark are reported to have been manufactured all through the 50s and into the 60s. An industry expert reported that 755a and 755c drivers show up with the same KS number on them and even some Jensen 8” drivers have been noted with a KS label. It is thought that the KS spec probably specifies something like an 8"speaker with a certain frequency range and impedance, which various units could fulfill.

In the very late 50's-early 60s, Altec produced a blue-grey colored model 755b for just a short time. It has been offered that this blue/grey color may actually be U.S. Navy Haze Grey. And it looks “haze grey”. But I don't know. It wouldn't be a stretch to think so. Western Electric being heavily involved in military contracting undoubtedly had access to all they wanted and at bargain prices. But this basically was a woofer made mostly from leftover 755a parts with a different cone support, just after production of the 755a stopped. It is thought that this driver appeared only in the first Lido series of speakers starting about 1959. By then, home audio was advancing quickly and power output of amplifiers continued to rise. The impedance of the 755 driver was changed from 4ohms to 8ohms to match it with a 402a woofer and the 15 watt Lido speaker series as well as the 755b were born.

Other than the different impedance, there are other telling differences from the venerable 755a. The 755a had an integral paper hinge that sufficed as the suspension for the cone. The 755b has a cloth surround that appears to have been glued to the cone edges. That makes an unmolested 755b immediately recognizable as the suspension has an orange color as opposed to the common black on all other 755 drivers. It has been offered that the cloth should give the 755b a lower resonant frequency giving this driver more “bass” response and making it more of a woofer than the full range 755a. However, as there are so few samples, I've not yet encountered anyone with a frequency spectrum analysis of the 755b. But given that information and the fact that the 402a driver was also a woofer, the Lido probably has a very full lower-end as it has no tweeter at all.

Altec 755c drivers appear in the early 60's handling 15 watts of power and sporting a green metallic frame. But most telling is the flatter “pancake” shape on the back as a result of changing from AlNiCo to a flat ceramic/ferrite magnet. However, this change along with a modification to the cone material and suspension resulted in a different sound. Magnets had to be changed as AlNiCo magnets are not particularly strong. They worked well in the early days of sound reproduction when affordable home-stereo components had very little power. But as amplifiers became ever more powerful, a stronger magnet was required to accommodate higher currents. As well a more cost-effectivecone material was suspended on a heavily doped suspension with one or two additional rolls, making the speaker more able to move freely, increasing bass response. Frequency response increased to 40-15000Hz but the flatness suffered. Audiophiles report the sound thicker, more bassy, therefore it is generally considered that the Altec 755c is no longer a full range speaker but a mid-to-mid-bass range speaker. It also has a dispersion angle closer to 90 degrees than 70 which affects the imaging.

In 1968 Altec introduced the 755e 20watt driver, white in color with different terminals for the wiring connections. These units are typically doped less heavily on the suspension, resulting in the lower frequency response being more solid, if moved up spectrum somewhat from the 755c. But aficionados generally agree that neither of these “pancake” models carry the full clarity and balanced tone of the venerable 755a although they are still considered to be quite nice and desirable drivers.

It is the original silver Western Electric 755a that appears to be the most desirable amongst true aficionados at this time. Even so, the 755b is the more rare offering due to their limited production. However collectors are by nature very specific in their desires and it is thought that if a measurement could be made, the 755b may be more bassy sounding than the crystal clear full range 755a.

Having opened the cabinets, I ultimately discovered that this particular pair of Lido model 836a speakers was supplied with Altec 402a woofer and model 755b full frequency driver so must have been the first series. Dad knew these Altecs sounded great. I wonder if he really had any idea why?

I also found that that one of the units has drivers that are both pristine. Unfortunately in the other unit both the 402a and 755b drivers have been damaged. Also unusual is that these 755b drivers have no logo/tag at all on them. 755a drivers are typically tagged as either Altec or Western Electric, or have the KS label.

While replacement cones have been noted on eBay, it is widely believed that there are no NOS cones remaining and what is seen are “reproduction” cones although they do not usually state this. Therefore an accurate rebuild is not practically possible. The good news is that during the course of my research I learned some repair techniques that enabled me to effect what I believe to be a satisfactory repair of those torn cones. The voice coils seem intact with the damage limited to paper tears.

I think the speakers should sound about as good as they did 50 years ago. However I have also learned that it is very important to listen to them properly. The 755a/b was designed with an unusually narrow sound channel so they should not be separated great distances. Which makes them perfect for home audio use. Also owing to that narrow channel, it can be argued that they reproduce stereo effects much more clearly than almost any current design. As has been noted, power handling for the 755b is in the range of 15 watts. Meaning that even inexpensive modern car stereos have enough amplification to overpower and damage these delicate antiques. Originally these speakers would have been driven by relatively low-powered tube amps of the day, so listening with modern high current amplifiers must be done with some care.

Having consulted with family, I am sure that the original grille cloth has been replaced, and somehow the original Altec logos got discarded accidentally or just for lack of interest. (blasphemy!) I have however scored replacements and will reintroduce them to their rightful place on the front of the Lidos. Those badges are shown at the top of the document.

My intent is to refinish the cabinets and enjoy the Lidos for some years to come.

Oh yes. I did mention the drivers being desirable among audiophiles, so what are they worth...?

Some searching on line seems to indicate that mint condition, matched response pairs of Western Electric 755a drivers are said to be worth anywhere from $4k upward to what a buyer will pay. Unmatched but pristine examples can bring $2500+.  Even repaired versions can fetch in the neighborhood of $1500+ as many feel that tears in the cone, if repaired properly do not affect the sound quality to any great degree. I recently found on EBay a slightly torn 755a sold at $1225. Even a pair of 755c baskets with voice coils intact but very rough looking, having no cones at all and needing a complete restoration...sold for $400 for the pair. But as previously noted, my research indicates that it is generally felt that no NOS cones exist any longer making a true “restoration” impossible for the average audiophile.

Altec 755b drivers are unique, reportedly having been used only in the Lido series of speakers. But due to very slight sonic differences, their value to collectors may not be similar to the 755a. A purist in search of specifically Western Electric” drivers may not be inclined to pay a premium for this rare Altec driver. However eastern aficionados seem to have an extraordinary interest in model 755 speakers. If it is the sound quality they are passionate about and not thelabela buyer may offer a similar bid for either model. As with anything collectable, the value is what the market will bear and markets are fickle. For example, 755c and 755e models are not nearly so valuable or sought-after due to the changes in design and the affect those changes had on the sound reproduction, although they are still very competent drivers.

I also have to admit curiosity about what their value might be if fully restored to original, cabinets and all. I suspect there may be a collector that would find an intact pair of Lidos in great condition worth more than the simple sum total of the drivers inside.

The website: is dedicated to documentation of the history and accomplishments of Jim Lansing, Lansing Manufacturing, and thereby Altec Lansing.   In that site's library is a brochure from 1963 identifying component prices of some of Altec Lansing's offerings.  To note on the last page of the catalog (effectiveJuly1,1963...)

836aLido Walnut cabinets$117.00

755c8" Wide Range drivers$29.95

402b8" Bass Speaker$19.50

It is interesting to note that this is a 1963 Pro series catalog and that neither the 402a nor the 755b drivers are listed. The 836a model cabinet is specified, but the drivers are shown as 755c and 402b. In the course of my investigation I have been advised by an expert in the field, that Altec produced two Lido versions. The early version with 755b drivers. And a later version with 755c drivers. Our family knows very little about the actual purchase of the speakers other than they were likely purchased at Allied Radio Electronics in Chicago circa 1962, which fits with the 755b driver. I suspect dad got them on sale, as the 755c driver was hitting the streets by 1963. So a clearance special makes a lot of sense. Dad would have been just about 27 at the time and having 2 boys and a daughter on the way I'm sure he was not flush with disposable income. Based on the spec sheet, my best guess is that the Lido probably sold in the range of $170-180 each. A princely sum in 1963, but 50 years later, that would make for a nice return on an investment.

Following are specifics for each unit as well as some supporting photos and documents.

But no matter whether labeled as Western Electric or Altec, 755 drivers are among the highest quality drivers ever manufactured and provide unparalleled clarity and true-to-life sound reproduction.

Altec Lansing like many companies has been restructured, acquired, renamed and and sold perhaps a dozen or more times in the ensuing years. But today, as the legendary name Altec approaches it's 75th anniversary, it is still synonymous with some of the very best sound reproduction in history.

Note that the suspension color on all these examples is black. The 755b sports a stylish orange color due to the different suspension material, it being cloth as opposed to paper.


Below, the s/n 271 755b driver. Note the stamped number 600760.
To the left is a symbol. It's the same symbol displayed on the speaker's labels, but I'm not sure at this time what that indicates.
Under the cones are another series of numbers that I guess are batch numbers for the cone manufacture. This one sports #21011 underneath just like the other 755b.

The schematic tag from inside s/n 271 confirms model 755b.

At least in these two specific cabinets:

Here is an image of the 402a driver in cabinet s/n 271. This driver shows a stamped 20889 on the underside of the cone, just like the other 402a driver. 

Then there is the stamped logo and the number 601130 on the gasket. It is generally known that this number represents the EIA mfg. code followed by the manufacturing week/year. Typically on 755a drivers, this is a 391xxx number, the EIA code for Altec being 391. The last 3 digits are supposed to indicate the year and week (YWW) of manufacture. So a code 601130 SHOULD indicate a driver manufactured in 1961, week30. It makes sense from what we know about the 755b.

But the paper tags on the back of the speaker cabinets show 611610. The scheme falls apart.  The speakers certainly couldn't have been produced in 1956 from drivers made in 1961!  And if the EIA code for Altec is 391, then who is 601?  Or 611 as noted on the cabinet tags? Given the discrepancies, and having discussed them at length with experts in the field, the markings on the drivers themselves will likely remain mostly a mystery. Altec (as do many manufacturers) produced various one-off builds, short runs of odd models, and various things such as this driver and many times they just aren't well documented.

Indeed one contributor offered:

You're not alone, being confused with Altec numbers. Often, part numbers are stenciled that have little coherence with typical mfg. process numbering schema. Additionally, Altec was known for using previous model components, transitional component models, and arriving at full production model components, all within one designated model speaker system. 

This is further verified by reports from the field that there have been found at least a couple of variations of Altec speakers labeled "Lido".

Referencing the image below, a close examination of the inside of s/n 271 reveals some interesting details (other than the nice set of fingertip prints ):

  1. On the left side of the cabinet, (bottom in this image) note the schematic tag (shown above). It is actually stapled to the wood inside the walnut veneer cabinet.

  2. Maybe it's just me but the wiring in here looks...well...amateurish. Strange criticism from one known to use bolted-together dog chain sections to suspend exhaust systems on Jeeps ...which worked fine for many years now that I think of it... but this just looks wrong. This is jacketed solid-core copper wire with the ends stripped /twisted and wrapped w/ electrical tape. Which obviously is not staying stuck together. The insulation in some cases seems to have been stripped back too far leaving a lot of copper exposed. The tech in me is cringing even though there is little chance for a short. The bell wire is stiff and stays where you bend it. But I can't imagine a manufacturer doing work like that. On the other hand I can't imagine my dad making connections like that either, but since I know the cloth was replaced, they had to be opened. He may have cut wires to pull the fronts out for replacing the cloth. At least the joints are soldered under the electrical taped connections.
    In any case it will be cleaned up and rewired. I may use the original wiring if possible just to maintain as much as possible the original components.
    As I have researched these speakers I have read many times that, especially in older speaker systems, in many cases they did have pretty tacky wiring inside.

  3. WARNING!:  Heads up to anyone who might have opportunity to come into contact with any very old hardware. 

    Some will note the yellowish/white head on the screws. The ones holding the speaker to the cabinet and the ones holding the bell to the basket on the 755b all look this way.

    It didn't sound right to me, but I thought they were nylon at first. Well they're not nylon but 1950s steel with a nice ...patina... I suppose some would call it. It's also noted on the 402a drivers. The “C” shape that bears the label is coated with this powdery substance. But the speaker structural support has some kind of slick coating on it and so is not dusty. The painted support of the 755b is likewise not dusty with corrosion. So when the cabinets were opened to have the cloth replaced, it seems unlikely that the drivers were unmounted.

    And apparently that is a good thing.

    I have been advised that this is likely Cadmium Sulfide dust which comes from the zinc compounds used in the manufacturing of the screws. It is a known carcinogen, a respiratory irritant, can cause nausea, diarrhea, abdominal pain and pulmonary edema as well as anemia, liver and kidney damage.


The interior of Lido s/n 256 looks similar to the above image of s/n 271.

It is somewhat interesting to me that the cabinets do not bear sequential serial numbers.

Likely I'll never know why they aren't.

Below is the 402a driver from cabinet s/n 256 sporting cone# 20880 and rim marking 600930.

This is one of the damaged ones. Doesn't look too bad does it?

Looks can be deceiving... Below is a closeup of the damage.

Yes the dust cap over the voice coil is pushed in.  BUT the paper is also torn along the face of the cone.

Then one side of the divided cone is separated from the surround for about 2”.

What is less obvious is that the cone is also separated for about 3/4”around the voice coil cap.

Below is that repaired driver from the top. The dust cover didn't pop out nicely as I'd hoped but is much better. The repair is smooth and seems secure.

In retrospect, I might have been better off applying the glue to the split from the back side of the cone. The repair from underneath looks even better.

See the images near the bottom of the document that show the repair from the bottom side of the cone.

Below is an image of the 755b driver out of cabinet s/n 256 bearing also cone# 21011 and gasket marking 600760. The damage is a little more obvious to the eye, but really not much more severe.
Is sort of an inverted W shaped tear. It doesn't go all the way to the voice coil, but cuts across the cone with a little waver in it before running back up to the suspension material. It was a little loose along the surround by less than 1/2”. Also has a small piercing just above the “middle” of the W. The dust cap is significantly dented

And after the repair...

WOW! Look at that dust cap. Popped back out quite nicely!

Repairs again seem solid and I think will provide minimal to inaudible coloring of the sound.

Below are images of the repair from underneath.


Above , the backside of the 755b cone

On the left, the underside of the 402 driver cone.

As can be imagined, after 50 years of moving and families and passing from one to another, the Walnut veneer on the heavy plywood cabinets is actually quite “distressed”, but in the coming months I plan to work them over and be listening to these beauties once again!


Subsequent to my publishing a link to this article online at a couple of forums I became aware of some specifically interesting information on these drivers here:   Blogger J-Rob is an anthropologist and archaeologist, Sound Practices Editor, and Consultant to Silbatone Acoustics.  He compiled a fantastic list of images for the 755 drivers that I've reproduced below.

This is the early Western Electric silver circa 1947.  Only made for about 2 years, this is the one that collectors covet most.
J-Rob notes that he saw a pair of these in mint condition sell online for $7,000+ in 2012.
Nice photo shows 3 of the six welds that  identify the Western manufacturing process vs. the Altec process.

And this slightly later version with the changed paint scheme.

Again, still Western Electric manufacture,  six welds showing.

And this 1952-1953 date coded Altec grey wrinkle finish.  

Note the missing weld(s)

And this which is the most common 755a found it seems. 

Was used in the Acoustic Research AR-1 speakers. 

Manufactured 1954 through about 1958, some silver Altecs have the old-style decal as noted on the grey wrinkle unit shown above.  

And the KS spec driver.   

These were procured for Western Electric internal use and show up in WE wall cabinets and telephone office each mount cabinets and the like.  

They are obviously made by Altec although they do not state the manufacturer in plain language, only via EIA code and it is not on all of them. The number of welds is also revealing.

Wallcabinets like the ones shown here may still be found in old churches,bus terminals, etc. and likely would have the KS 755a driver inside.

For some unknown reason, KS units can cost more than identical Altecs and some people have themselves convinced that they sound better too even though the manufacturing process and the components used therein are identical to other 755a examples.

Here is the cone of the KS spec 755a.

Note the Western Electric inspection stamps on the gasket.  

It also shows the mfgr. code 502588

HOWEVER, the EIA code for Altec is 391xxx and that is what is usually seen on KS-755As. 

It's apparently unknown who the 502 EIA code was assigned to.  Could some of these KS units have been assembled or marketed through a third-party subcontractor?