tysontom

I think this book should be generally about the company, its people, financial reports, products and how the company changed the course of high-fidelity history. I also don't think a lot of people would want to read the book if it were too technical; therefore, I think it should be about the people and products, and how they contributed to the remarkable success of the company. One thing I don't have are pictures of the original operation in Cambridge. I have very few vintage, original pictures of 24 Thorndike Street in Cambridge. I have nothing on the Mt. Auburn location where it began. In Norwood, I personally took a lot of pictures of testing, the anechoic chambers and production lines, etc. In the book, there would be some technical discussion to explain what AR actually accomplished, and how it was done, but no heavy technical stuff. References to the many disclosure articles by Villchur and Allison would serve that purpose. This is one reason I wanted to get feedback from people on the forum as to what they would want to see in this book. Specific models, how they were built, what years, and that sort of thing. AR's Music Rooms, AR 5-Year Warranty, AR's Live-versus-Recorded concerts, and that sort of thing, too. There might be chapters (such as the AR-3a restoration guide, with permission, to be included) that go into some restoration hints and so forth. Most of the books that I have seen on the subject (there are books on Paul Klipsch, JBL and so forth) deal with the products but not great detail or specifications, particularly. Thoughts? I would really like to hear from everyone who might be interested in this book, what they would like to see it become. There are very few of the original AR employees and individuals still alive now, so this is a problem. Many of that generation left have forgotten many details, thus some things remain mysterious. Fortunately, I have the AR Archives, and there are secrets held there on marketing/development decisions, etc. --Tom

>I also recall having read the same detailed information from Stereophile, and I assume its correctness against what appears to be a sort of revisionist article containing conflated timelines, unattributed premises and boot-strapped conclusions. >I've been wishing & hoping for Tom Tyson's definitive AR history for years...would a GoFundMe effort be in vain? —ar_pro Book: The History of Acoustic Research Any and all suggestions and ideas here would be greatly appreciated! Any thoughts about what you would like to see would be great as well. To do a complete history would be difficult, but a history of the "Classic Period," from 1954-1974 (or 1980 perhaps) in one part and the Teledyne/International Jensen/Recoton/Voxx period in another part or in a revised edition. The most important part of AR history is the first 25 years or so. Anyway, please reply with your thoughts and ideas, for example: The best title for such a book? The period covered with this book; part of all? The amount of detail to be included in this book? The size of this book, a small book with 150 pp or so, or comprehensive with perhaps 300 pp? The other questions you might have. There are also many people here on this website with detailed knowledge of specific aspects of AR history and technology. Therefore, give me ideas about how you would like to see such a book. —Tom Tyson 06Jun2017

Dear Glitch, I'm glad to hear (though this is a few months later) that you are happy with your L1590s! I think the 1590s were superb, especially in a large room, but the speakers have to be positioned properly for best results. When I had them at first, I had them in a large, relatively damped, living room, and they sounded superb. I still have my L1290s, and although they are excellent speakers, I never liked them quite as much as the 1590s. I suspect that the 1590's lower midrange crossover and extended deep-bass output accounted for that difference. Have you compared the two systems yet? I'd be curious to know your impressions. By the way, it's really hard to believe that there have been nearly 60,000 views of this one topic concerning the this one superb loudspeaker system. When I began the topic, I made a mistake: I said they were "a/d/s/ L-1590," but I meant "ADS L-1590." The new logo had not been adopted until the "M" series arrived a few years later! I wasn't thinking, but then it was too late to change the topic. --Tom Tyson

I overlooked this post regarding the less-expensive option for mahogany vs. walnut for cabinet finishes. In the years prior to the growing popularity of oiled-walnut finishes used in the furniture industry, the typical wood finish for furniture cabinets was mahogany. For many years prior to the high-fidelity industry, case-goods furniture manufactures had perfected lacquer and varnish finishes for mahogany, walnut, cherry and birch, etc, and it was natural for speaker manufacturers to follow furniture trends and to get cabinets from their vendors in lacquered mahogany or lacquered walnut (or birch, cherry or korina, too). Production costs were lower, too, due to the popularity of mahogany during that time. When oiled-walnut came along, the costs did go up somewhat because applying oil finishes is somewhat more labor-intensive—often done by hand—for the cabinet manufacturers, and this cost was passed on to the speaker companies. In addition, walnut was more more expensive than mahogany. Therefore, the oil finishes had a slightly higher mark-up in the price list than lacquered finishes. —Tom Tyson

There is really no prettier loudspeaker than the lacquered-mahogany AR-3. Here are a couple of other pictures for reference: The lacquer finish is not glossy so much as it is semi-glossy, smooth with no grain showing. It is akin to the Steinway piano finishes, done the same way. The speaker (one of two) looked shiny, but it was due to the flash used. --Tom Tyson

Hi Luigi, You're right that it is the "New-Look" Mark II version, but I think the AR "Advanced Development Division" marketing people probably used whatever they had to make the cutaway versions. The "ADD" moniker went away pretty soon after the "New Look," too. These cutaway versions were also very early in the Mark II process, but there are no serial numbers on either of the display speakers. AR also made a beautiful, single AR-3 cutaway, but it was apparently dismantled at some point. This speaker was on display in the AR Music Room in New York's Grand Central Terminal. It was powered by a 5 Hz sine wave, with the woofer slowly pumping back and forth to show the acoustic-suspension principle. There was a Plexiglas AR Turntable, but it too was destroyed. Fiberglass was used well into the later versions, but I don't know the date of change to polyester. Another thing: fiberglass can be placed in "squares," to appear to be neatly packed inside the cabinet, whereas polyester would be all over the place. The woofer voice-coil former is Nomex, commonly used in this woofer, but late in the 70s AR began using aluminum for the former. Aluminum dissipates heat better, yet Nomex can stand higher temperatures. --Tom

Yes, yes. There I am explaining the intricacies of the Electro-Voice Interface A. That is Steve F "glazing over."

Hi Luigi, I'm unsure of the details of the England and Holland production protocol; I do know that the drivers were originally produced in Cambridge, Massachusetts (and later in Norwood) and shipped to Europe. Later, some drivers were produced in Europe along with cabinets. I need to research this a bit to find out what happened. However, I honestly don't know how Teledyne AR worked the serial-number range. For example, I always understood that the orange tweeters were non-Ferrofluid drivers and that the black tweeters were Ferrofluid, yet the serial number of Jasper's (Patagora's) AR-10s fall into the Ferrofluid-tweeter range, another mysterious thing in the world of high-fidelity loudspeakers! I do agree with you that the "E" and "H" preceding the number indicated England or Holland production. Veering off topic a bit, Acoustic Research at first used an export service, Delrama, Inc., to ship products across the globe, but later expanded production and testing into Europe. Delrama became unnecessary, and I acquired quite a lot of NOS products that came from Delrama inventory, including the last existing AR-3a "cutaway" speaker. It was number 2 of 2 made, I believe; the first two were dismantled after the AR Music Room was discontinued in 1973. The AR-3a "cutaway" was a hand-made work of art made by Sumner Bennett with the help of AR's cabinet-maker. After this one, the "cutaway" AR-3a is extinct, but it will be protected. The AR-3a "cutaway" is similar to the AR-11 "Visible Speaker," another rare item. The AR-3a "cutaway" was used in Italy, Germany, England, France and Holland as well as in shows in Australia and China from time to time. It traveled the earth.for several years, starting in 1968, accompanying executives from Acoustic Research, such as Roy Allison, Sumner Bennett, Martin Borish and Gerald Landau. After AR went to internal, self distribution, Delrama was out and didn't know what to do with the AR-3a "visable," so I acquired it from them along with their existing inventory of NOS AR-3, AR-3, AR-3a and AR-1 service-replacement parts. I've given most of those parts to AR friends in need. The AR-11 "Visable" was an attempt by Teledyne AR to do the same thing with their Advanced Development Division speakers, and several (probably a dozen or more) of the "Visable" speakers were made available for franchised Teledyne Acoustic Research dealers in the US (and perhaps Europe, too). It could be purchased with a small sine-wave generator and amplifier and an AR metal speaker stand, but only a few dealers opted for this interesting sales aid. I apologize for straying off topic (original topic was the AR-10). --Tom Tyson

As others have indicated, these are definitely AR-10π speakers—the original version—sometimes unofficially called the "Mark I" version. The original version is characterized by the use of the brass logo plate, the yellow-orange ¾-inch soft-dome tweeter, the earlier AR-3a-style woofer and the solid-veneer back panel (which easily delaminated in use and was later changed). Serial Numbers in the 4600 range. I think this particular pair are European (Holland) versions and judging by the serial number, this pair was likely built in October or November, 1976. In the US, AR began using Ferrofluid tweeters on September 22, 1976, beginning with serial number 6278, and this pair has a later serial number; however, most of the Ferrofluid tweeters were black rather than orange, so this might have had the earlier tweeters, perhaps shipped to Europe. The second version of the AR-10 with the "new look" came in June, 1977. —Tom Tyson

Checking the crossovers might not be a bad idea, but the likelihood of bad capacitors is not high considering the quality of the components ADS used in this speaker. To check each capacitor, you will have to remove at least one lead from each capacitor (being checked) on the crossover board. It's also possible that something might have happened to the speakers before you acquired them, and they may have been subjected to excessive input power levels for extended periods, which could affect the crossover as well as the Ferrofluid in the voice coils. I can also see from the images that it looks like the woofers (at least the top one) may have been removed. The edge of the cabinet above the woofer seems to be slightly scratched, but it could be an optical illusion, as the picture is not completely in focus. If a woofer has been removed for some reason, the phasing and integrity of the wiring should be checked. Again, explain the amplifier being used, what type, rating, etc. I didn't look it up to see what configuration. Some amplifiers don't work well with these speakers. Thanks, and good luck with these speakers. I hope you get to the bottom of the issues! --Tom Tyson

Can you send some pictures of your two recently acquired ADS L1590s (are they first models or Series 2?), your amplification and input-source setup and the room in which they are being played? What you describe about the sound quality is the exact opposite from what most people sense from these speakers, and it makes one think the following: You have major electro-mechanical issues with the speakers themselves (have been over-driven, modified or damaged by a previous owner); You have issues with your electronics, either incompatible or insufficient to properly drive the speakers; Your room is not well-suited to the speakers or they are arranged improperly; You have the speakers out of phase; You have become too familiar with the sometimes excessively "bloated" bass response from the Definitive Technololy BP7002 home-movie speakers. Thanks, --Tom Tyson

Yes, it's always tough to part with something you have enjoyed through the years. I hate to admit it, but I grew attached to audio equipment that give me musical enjoyment!. Nothing is forever, though, and perhaps it is better to pass these wonderful speakers on to another music-lover to enjoy for another 30 years or so. I'm lucky that these ADS 1590s held up so well, and I really never had to do anything to them, but I never abused them. A good friend, and my family doctor at the time, wanted them very badly back in the early 90s, and I sold them to him. He kept them for several years and played mostly small-ensemble chamber music with them, and they were never ever stressed to my knowledge. The most important thing is that I held on to the speaker cartons (I kept them sealed in plastic bags to protect the cardboard), even while he owned them, and then one day I had them back again. I think the new owner, I think a perfectionist and ADS-admirer in his own right, seems to be very happy with them! UPS was a little rough on the cartons during shipment, but the big boxes did what they were designed to do, and the contents were protected in transit! Big ADS L1590 in its protective shipping carton. As for my collection (and I still have a way to go), I will thin it down to a few pairs of speakers. I enjoyed collecting these speakers, and many have grown in value over the years, so it wasn't a bad investment! I still have KLH Sixes and Fours, AR-2s, a pair of walnut ADS L1290/2 speakers (which I like nearly as well as the 1590s), a pair of AR9s that I am slowly restoring, a pair of mint AR-LSTs and a very early pair of AR-3s, etc. I also have a pair of AR-303As (I'll probably sell these at some point). Some of these items are gone, but many are still in place! Time to let other people enjoy them. --Tom Tyson

I recently sold these beautiful ADS L1590s after nearly 30 years of ownership. I have been downsizing some of my equipment, so it was appropriate to let someone else enjoy these wonderful loudspeakers. Packing and shipping a speaker system this large is not an easy task, but with the original shipping cartons, the speakers are safe for normal shipment. The importance of keeping the original shipping cartons cannot be over-stressed. I took pictures of the process and I've attached a document showing that process. ADS-L1590-2_Packing_Tyson.pdf --Tom Tyson

No, I haven't bi-amped these. It is easy to do, but I haven't tried to do it. By the way, I am downsizing some of my equipment, and I have decided to put these L1590/2 speakers on eBay (322343347803) These are the same ones shown in the original pictures I put on this post. They have been great loudspeakers (as good as anything I've ever owned) and very musical and enjoyable, but I need to slim down the size my audio collection. I still have a lot of equipment, so it's just a small dent. --Tom Tyson

Nothing fancy. I use a QSC PLX3602 pro amp with a Crown preamp. The QSC is in a cabinet that closes off the sound of the fan. In the past, I've used a Crown Macro Reference amp and a McIntosh MC2275 and later a MC2500.

Ha-ha! Good one. First of all, the ADS (and a/d/s/) speakers were for the most part American-made except for the very early versions, which used the Braun drivers. Strangely, the cabinets on several models were fabricated in German and shipped to the US! The 1090, 1290 and 1590 cabinets were made by a German company, but those speakers used US made and designed drivers. What is the "superior" quote? Don't get me wrong, I greatly admire just about anything designed and made in Germany. I own both AR and ADS speakers, too!

Hi Glenn, You are certainly fortunate to have so many outstanding speakers in your collection! The midrange restoration on the AR-3 done by Roy is a step in the right direction, but the smoothness and accuracy of the driver after the change is not assured; only in output is there an improvement. So there would be a trade-off in output quantity for output quality, yet the old midrange drivers (those with the white butyl-rubber substance around the gap) do drop off in output over time in most cases. It's a shame that your LST-2s had bad tweeters! The original 3/4-inch hard-dome tweeter is a very fine unit when it is working correctly, and it contributes a great deal to the natural AR-LST-2 sound. One problem I found with the LST and the LST-2 is that the output sensitivity from each of the tweeters began to vary as the speakers aged a bit, thus putting the tweeters in peril if one got too much energy. It actually takes a pretty good amount of power into the tweeter to cause thermal issues, but people always manage to do it. The 910 is certainly a fine, accurate speaker, and it was widely used professionally for many years, too! It actually has a nearly ideal balance between wide dispersion and good on-axis performance, and many listeners prefer this characteristic. The ADS tweeters are consistent and well-behaved, and they tend to be durable, too! I listen a lot with my ADS L1290/2 and L1590/2 speakers, and I never tire of their sound. --Tom Tyson

Glenn, The ADS 910 has always been considered a fine loudspeaker, but when you say you found them to "outperform... AR12s, AR-3s, AR-LST/2s, KLH Fives..." I think you mean that you prefer the ADS 910s to those speakers, not that they will outperform them, for they won't. For example, the AR-LST/2s easily have flatter and more uniform power response into the reverberant sound field than the 910s, meaning that the LSTs are much more spacious and 3-dimensional when properly placed and when listed to well back into a listening room. The 910 has superior low-frequency output when compared with the LST/2s, but throughout the midrange and treble, the dispersion and smoothness of the LST/2s is far superior to the 910. On axis—and up close—the 910 is certainly as smooth or smoother than the LST/2, but not off axis. The AR-3, if it is in 100% original working condition, has slightly lower harmonic distortion than the 910 down in the deepest bass range, but the 910 has a somewhat lower resonance frequency and bass extension, somewhat greater overall power-handling capability. The 910 can't equal the AR-3's woofer in low harmonic distortion, especially at frequencies below 40 Hz, but few speakers can match, let alone surpass, the AR-3/3a in low distortion. The AR-3, in original working condition, is probably smoother in the midrange and treble as well, but high-frequency response declines more rapidly in the AR-3 than with the 910, making the AR-3 sound more reticent, and the biggest problem for the 55-year-old AR-3 is that only a rare few models left today still have sufficient output in the midrange and treble to be comparable to their sound when new. The sensitivity of the dome midrange and tweeter in the AR-3 (and the tweeter in the AR-3a, AR-5 and LST/2) tends to drop off the older the speaker get, unless these speakers had been stored in climate-controlled areas for many years in boxes, etc. Yet overall, it's what a listener prefers that counts in the long run. Some speakers do better when listened to up fairly close; others do better when listening back in the sound field, as with most of the AR speakers of the earlier generation. Nevertheless, the 910 is one of the premier loudspeakers from ADS, and it has always been a reference standard in the industry. —Tom Tyson

DavidDru, I'm glad to learn that you have restored your L1590s and got your midrange and tweeters refurbished from Richard So. I think he is the one from whom I bought several ADS replacement parts, such as woofer cone/voice coil replacements, new midrange and tweeter dome top plates, etc. I've never had to use any of them, but it is good to have those replacements, and it is nice that ADS went to the trouble to make their drivers so easily restorable. Let me know how you think the 910s sound when compared with the 1590s. The 910s were very fine speakers, but they were not quite as robust and refined as the 1590s. I honestly can't imagine the need to replace the crossover components on any of the up-scale ADS speakers in the L series. ADS L1590 and L1290 (and L1090, among others in this family) crossover capacitors are computer-grade throughout, and all of the crossover components are premium quality, and I think they will last a long time. The impression I have is that few people have to update the crossovers in ADS speakers of this generation. I have never attempted to replace anything on either my 1590s or 1290s, but both sound pretty much exactly as they always have sounded! Neither my 1590s nor the 1290s has ever been driven hard (other than brief bursts of high power) over the years, and neither has been in constant use over the years. I really don't see any signs of deterioration over time, but I'm sure all speakers gradually deteriorate very slightly as the years pass. As for the cabinets, the finish is lacquered, and to repair or refinish will require more detailed steps than the simple oil finishes. However, use of the new poly finishes, such as premium-quality Mohawk Pour-n-Wipe, and similar wipe-on polyurethane finishes, can probably be used on these lacquer finishes once the original finish has been sanded sufficiently. The end result would probably be very similar to the matte-type luster of the original ADS finish (done in Germany, incidentally). —Tom Tyson

Roger, The large AR live-versus-recorded concerts were with the AR-3/Fine Arts Quartet. 75+ concerts in 5-6 cities across the US: New York, Boston, Chicago, LA, Philadelphia and Washington, DC. Probably 10-15K people attended the Fine Arts Quartet concerts alone. Next were concerts done with classical guitarist Gustavo López and finally a demonstration with a 1910 Nickelodeon. No one has ever attempted a facsimile live-versus-recorded demonstration with a full orchestra; Wharfedale attempted it around 1955, but the comparison was flawed. Looking back in history, only AR has successfully attempted live-versus-recorded demonstrations where the audience was unable to consistently detect the switch-overs from live to recorded. Important: neither Ed Villchur nor Roy Allison ever "voiced" AR speakers for a particular sound. Both were interested in power response; i.e., the maximum amount of energy propagated into the reverberant field. Both were interested in maximum smoothness and maximum dispersion; both were interested in the lowest harmonic distortion, but there was never any "voicing" of the speakers. "Voicing" is a purely subjective way of designing a speaker, and a lot depends on the whims or tastes of the designer or engineer. AR was more into the objective results of quantitative testing and measurement. These end results were done primarily in the anechoic chamber and reverberant chamber with final listening tests to verify results. What measured well nearly always sounded good, anyway. Speaker designers such as Henry Kloss of KLH and Advent, and Andy Kotsatos of Advent and Boston Acoustics did "voice" their speakers almost exclusively, and they got good results, but AR did not. --Tom Tyson AR-3s and Fine Arts Quartet Concert Carnegie Hall AR-3 guitar LvR, Dave Jones with Ampex 351 in background.

I certainly agree with Steve's assessment of modern-day costs, if only based on the current "inflation" calculations for costs. In reality, I think an AR9 might easily exceed even $10k considering the types of components, etc. Unfortunately, the inflation calculator is based pretty much on the rate of inflation, and with a very depressed economy for the past 8-10 years, it's really hard to make a clear judgement on actual costs since our economy has nearly approached the point of retraction rather than growth. Labor rates would be significantly higher, too, and a speaker such as the AR9 would have significant manual labor involved, especially with the large oiled-walnut cabinet. But at $10k, I would think the AR9 would be a bargain in today's money! There are probably few loudspeakers -- even current models -- that can outperform the AR9 in overall performance. I really can't name any speaker that is smoother in overall response, has lower distortion with lower bass resonance and wider dispersion than the AR9. Some might outpoint it in one or two respects, but none to my knowledge is better overall. Can we name any? It would be a good comparison. As for the modern "equivalents" to sealed-system loudspeakers, the formula for the "pure" acoustic-suspension" woofer has constantly evolved. In the early days of AR's AR-1, AR-3 and AR-3a, the woofers were very, very compliant and contributed to less than 20% mechanical restoring force vs. 80% or so with the contribution of the sealed cabinet's air. Mechanical restoring force was the minimum necessary for physical centering and stability of the voice coil in the gap. For years, the lowest-distortion woofers were made by Acoustic Research and were rarely equaled, let alone surpassed, over time even to the present. However, today's drivers are built more for longevity than low distortion, insofar as most listeners can't readily discern levels of distortion. Today's woofers are significantly less compliant (I've heard that it's more like 60:40 than 80:20), even those with low free-air (fs) resonance similar to the originals. Therefore, there is more contribution from the mechanical components of the woofers themselves -- such as the inner (spider) suspension and the outer (skiver) surround suspensions -- in the interest of mechanical durability and reliability. With today's taste in music, probably a smaller group of listeners (those still interested in audio) listen to classical, organ or jazz than listen to modern pop music, so the deepest registers of bass are rarely plumbed with today's equipment. Some do like electronic music, but there is no analog in real life, making distortion is very difficult to detect. Major exceptions to this would be large, powerful subwoofers, particularly those with servo-tracking voice coils. Velodyne Acoustics comes to mind, of course, and the woofer servo mechanism counteracts the fairly significant mechanical distortion generated by the big, stiffly sprung woofers to give very low harmonic distortion in the final output. But with stand-alone speakers, it is a different matter. --Tom Tyson

Audioholics, an on-line audio publication, has just published my tribute to Roy Allison: http://www.audioholics.com/news/a-tribute-to-roy-f.-allison --Tom Tyson

Roy Allison, from Steve Mowry interview in Australian HiFi, Jan-Feb 2011 Roy Allison, 88, died on March 1, 2016 in Manchester, New Hampshire after an extended illness. He is survived by his wife and three children. Mr. Allison was an acoustics researcher, loudspeaker designer and author of dozens of audio articles and a book, High Fidelity Systems, A User's Guide. His contributions to the science of sound reproduction are well-known and respected throughout the audio community. In 1959, he began work at Acoustic Research, Incorporated as Assistant to President Edgar Villchur and soon became chief engineer and then plant manager; by 1967, he was made Vice President of Manufacturing and Engineering. He helped the company maintain its industry leadership for many years and was instrumental in the creation of many of the company's most time-honored products, including AR-3a, AR-5, AR-4x, AR-6, AR-7 and AR-LST loudspeakers, the AR Amplifier, FM Tuner and Receiver, as well as improvements to the AR XA Turntable. His continued vigilance of AR's industry-leading customer-service policies and internal employee relations helped the company maintain its industry-leading position for many years. After leaving AR in 1972, Mr. Allison did research into room-boundary acoustics and its interaction with loudspeakers, and in 1974 he cofounded Allison Acoustics, Inc., to build loudspeakers of his design (under his 1975 patent #3,983,333) to specifically address these room-boundary problems. Allison Acoustics manufactured many highly respected, successful speakers during this period, such as the Model One, Two, Three and others. By 1990, Mr. Allison formed two other companies, RDL Acoustics and RAL, primarily a mail-order loudspeaker business. In 2000, Allison Acoustics was revived by new owners and moved to Kentucky, where new products emerged, and by this time Roy Allison retired to write and to perform freelance speaker design. —Tom Tyson This is a brief obituary on Roy Allison. Further information and a detailed obituary will follow.

Attached is the owner's manual for my pair of ADS L1590/2 loudspeakers, and it may have some helpful information for those with the series 1 as well, but there are some differences, some noted on the final page. ADS_L1590-2_Owners-Manual_Tyson980.pdf --Tom Tyson ***Update: the manual supplied by ADS was actually for the Series 1; but rather than print a brand-new owner's manual for the Series 2, ADS added a supplement at the very end (shown with my manual) describing the differences. Therefore, this manual works for either the Series 1 or Series 2.

Claudel, I just now read in detail your post from back in October and your interesting story about Vietnam and your AR Amplifier, AR Turntable and a pair of AR-4x loudspeakers. What you had was a excellent combination that was pretty much unsurpassed for a small but very accurate sound-reproducing system! To this very day there aren't many systems that size that would sound better! Overall, I don't see that we're in too much disagreement, but I think I can see some discrepancies in dates, etc. The AR Amplifier was definitely introduced at the New York High Fidelity Music Show in October of 1967, but it is true what you say that the first full year of production was 1968. If you got your amp in December, 1968, it was well into production with many thousands of units having been produced, and your unit was by no means an early version. I'm pretty confident that first production commenced about that time of its introduction in 1967, as the amplifier had been pretty carefully sorted out and tested for several months leading up to its introduction. There may have been some delay, but not much. AR was eager to get it into the hands of dealers worldwide. The first AR Amps definitely had the closed-in perforated screen that covered the heat sinks, and the amp had adjustable bias and several other things that were changed later on. The first AR amps did, of course, have the "Inc" printed on the front panel beside the "AR" inscription. This changed to "AR" at some point after the amp went into production because there was no more "AR, Inc." after 1967. It was simply "AR" and then "Teledyne AR." AR was sold to aerospace company Teledyne, Inc., in June of 1967. I suspect that when the stock of "AR Inc." plates ran out, all new ones were printed with simply "AR," but this may have been well into 1968. Early AR Amplifiers had a tendency to overheat (although some soldiered on indefinitely while the back of the case would get so hot you could not touch it), and many went into failure mode and would blow out the output fuses, etc. Those who foolishly over-rode the protection fuses would find huge dc-offset in the output, which would fry any woofer's voice coil and "freeze" the woofer in place. That's another story, but it was not uncommon, and this failure happened to two of my early amps driving my AR-3 loudspeakers. AR took care of everything, of course, and I suffered no damage to the 3s. To improve the heat-sink heat dissipation, the screen cage was pulled back away from the heat sinks to allow better air flow, and this helped the amp run a bit cooler (though AR Amps always dissipated a lot of heat once running along). This happened sometime in 1968, but I'm unsure of exactly when it occurred. I've attached some images that may clarify this situation. Note, too, that unless you bought your AR equipment in Europe of Asia (not the US commissary), you would not have come in contact with Delrama, Inc., the AR exporters of equipment prior to AR's UK and Holland plants. This is an original "file" photograph taken of the Amplifier before it was officially introduced in 1967. Photo was consigned to me. This shows a close-up of a rather battered early version (#131) AR Amplifier made around November, 1967. Shows the "AR Inc" on the front panel. This was used until well into 1968 or perhaps 1969, but probably after stock was depleted of old units. Thanks, —Tom Tyson