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AR-3a and AR-11's


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I was wondering what the difference is between the AR-3a's and the AR-11's? they look almost identical. It even looks like they have the same drivers. The only difference I can see is that the AR-11's are shorter and fatter. Which one is better?

THanks,

A

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The AR 11 was a contemporary of the 10pi, without the environmental controls...it was basically an AR3a in a newer, more "modern-looking" cabinet. They made a steel stand (designed to fit the 10pi and 11) that raised the speaker about a foot from the floor...it was an attractive combination, and is not often seen. These were top-of-the-line speakers that were then replaced by the first iteration of the AR-9 tower design. Arguably, the AR-11 was the last "real" AR-3a !

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  • 4 months later...

The AR-11 was introduced in March 1975, along with the 10Pi and AR-MST as the initial products in AR's ADD (Advanced Development Division).

It was a 12-inch, three-way speaker, using the same foam-surround ferrite-magnet woofer, and 1.5-inch dome midrange as in the AR-3a. The .75-inch tweeter was new, however. Although it was the same size and looked outwardly similar, it used ferro-fluid cooling around its voice coil. This was one of the first speakers in the industry to do so, although there is a little controversy as to whether AR or EPI was actually the first company to get a ferro-fluid cooled speaker to market.

The use of the liquid cooled tweeter allowed AR to re-do the crossover and considerably raise the drive level to the tweeter, since its power handling was now so much greater. The result was that the 11 (and 10Pi ) have a greatly improved high-end response compared to the 3a, while retaing all the 3a's attributes of smooth response, low distortion, and wide dispersion.

The 11 can be considered the ultimate development of the basic AR 12-inch "bookshelf" speaker. It's response was exemplary. It's smoothness and lack of distortion were unexcelled. Most speakers today would be hard-pressed to match its performance. A pair of AR-11's in good working order is a superb speaker, by any standards.

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  • 2 weeks later...

I agree, the 11's are superb speakers. I bought mine in 1976, and only in the past few months have I rebuilt them and returned them to original. They sound absolutely awesome!! My question is........how big of a step up is it going from the 11's to the 9's? I've never heard a pair of 9's, but I've heard a lot of good things said about them.

Helix

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Hi, Helix -

The Model 9 shares the sonic "signature" of AR's best efforts, but with some significant differences. Acoustic Research achieved its finest low-end reproduction with the 9 - it is effortless, powerful and natural, with an extension that qualifies it as a legitimate subwoofer. The dynamics of this system are also unmatched by previous AR designs (the superb LST not withstanding - it is a master of dispersion and neutrality, but it cannot achieve the absolute full-range output of the 9), and are truly awesome when the speaker is driven by sufficient wattage. The 9 also effectively addressed the issue of imaging, by way of its vertical driver alignment and Acoustic Blanket - two important attributes (along with that outstanding low-end response) that make the design a superbly musical and viable high-end loudspeaker a quarter-century after its introduction.

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Helix;

You will never forget the first time you heard a pair of 9's. It is like your first kiss, your first......

I heard a pair in 1978, but did not have anywhere near the money to get them. Came close in 1982, but not quite, girl friend got AR91's, did not have the budget for 9's.

The AR91 is basically a floor standing version of an AR11, with the drivers arranged in a verticle line.

Five years ago, I started watching e-bay, and finally 1½ years ago, I got a pair in very good operating condition. I have since picked up a 2nd pair that needs refoaming.

Nigel

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The AR-11 had the 3a-style midrange with the damping pad and metal-mesh protective screen; the 91 had an exposed 1 1/2" dome midrange in a shallow horn-loaded structure.

The 11's woofer to mid x-over was 525Hz; the 91's was 700Hz. I owned both of these speakers and A-B'd them at length in my home. Although the 91 was very good and quite attractive as a floorstanding speaker, I actually preferred the 11 slightly.

Steve F.

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Yes, the 91 was a nice 3-way system with the 12" woofer, but I agree that the 11 or 10pi was a smoother-sounding loudspeaker. Perhaps the use of the upper-midrange dome from the AR-9 series (a 4-way system, that also used an 8" lower midrange driver) was not an appropriate choice, and with its higher crossover frequency, was asking for too much midrange performance from that 12" woofer. I wonder if this was a marketing decision (the 91 essentially replaced the 10pi and 11 as AR's big-woofer, 3-way system), or if the designers really believed the 91 to be superior to its predecessors.

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With all this discussion of 3a's and 11's, I am hoping someone is familiar with what AR did in creating the 58s's. I have a pair of these I bought at a second hand store a while back. They have the usual 11" woofer with a 3/4" exposed dome tweeter amd 1.5"exposed dome mid. These drivers do not look like those in the 11, but more like those in the 9. These speakers sound pretty much like the 11's. Were these made after the era of quality and thus use inferior mid and hi drivers???

Thanks

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In my opinion, for what it is worth;

I think that the 58/48/38/28 were amoung the last of the better ARs.

There are several different models in this series, some with dome mid ranges, some with larger cone midranges.

Nigel

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>In my opinion, for what it is worth;

>

>I think that the 58/48/38/28 were amoung the last of the

>better ARs.

>

>There are several different models in this series, some with

>dome mid ranges, some with larger cone midranges.

>

>Nigel

I must admit, my off-the-top-of-my-head total knowledge of AR speakers begins to wane after the AR9/91/92 series. But the 58/48 et. al. speakers started off as very respectable speakers though they certainly were not the engineering standouts from their competition that the original 3, 3a, 2a, 2ax, etc. were.

This series went through several iterations (48B, Bx, Bxi, etc.), and if you paid really close attention to the specs, you could see evidence of cheapening and corner-cutting as the years went by.

The woofer to midrange crossover frequencies went up over the years, which shows that cheaper, smaller chokes were being used, and the company didn't care as much about things like midrange dispersion, energy response, etc.

This was the time when AR really began their final market slide, away from the tenets of the original founders, to just another box-stuffer, trading on a great name of the past. The "58Bxi" was not anywhere near as significant a product on the audio market as was the 3, 3a or 11.

Steve F

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I've always wondered about the 28, 38, and 48 series of speakers, because it seemed as if they had little in common with the Model 9 and its derivatives - almost like they had been designed and manufactured by someone else...I'm betting that these vinyl-clad boxes had OEM drivers in them! This may also have been the first iteration of the "different lines for different dealers" approach (remember the "Connoisseur" series?), a bone-headed notion that helped to drive the once-great company right into the ground.

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Just looked up the paperwork on the 58s. The original booklet was printed 1981 and the pair I have was purchased new for $550 plus tax. I am second owner but have orig receipt. The booklet confirms 3/4 liq cooled hi dome and 1.5" liq cooled mid dome with a "semihorn dispersion ring. these 2 drivers appear just like those on the 9, even down to the white ring on the tweeter flange. The booklet does confirm lesser components for the rest of the series, like a 1" dome tweeter for the 48s. I will try to scan this sometime and submit it.

I am assuming that the "s" series may have been in the early phase of the decline??

Steve

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>Just looked up the paperwork on the 58s. The original

>booklet was printed 1981...The booklet confirms 3/4 liq cooled hi dome and 1.5" liq cooled mid dome with a "semihorn dispersion ring.

>these 2 drivers appear just like those on the 9, even down

>to the white ring on the tweeter flange.

The original 58 was essentially a 91 in a bookshelf format, although in light of today's typical 6 1/2" 2-way 15-lb bookshelf speaker, what "bookshelf" would hold a 50-plus lb AR-58?

Around this time, AR farmed out their driver manufacturing to Tonegen/Foster of Japan, a large OEM supplier to many speaker companies. They made close copies of the AR drivers, even down to the truncated 12" woofer basket and the metal mesh over the 1 1/2" midrange. The switchover in driver sourcing took place in the mid-80's. so the early 58's may have had domestically-produced drivers. I'm not sure.

(BTW, why is AR's 12" woofer sometimes referred to as an "11-inch" woofer? It's a 12" woofer, since industry-standard practices are to measure the outside of the frame, not the cone itself, or even to the edge of the surround. It's just the standard driver measurement technique, and no one--not AR or any other company--is trying to "get away" with anything.)

As AR slipped further into decline, the later versions of the 58 (and 48, 38, etc.) had a cone midrange and a gimmicky decorative plastic flange around the midrange and tweeter.

Steve F

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  • 3 weeks later...
  • 2 weeks later...

 AR 11 and AR 10 PI were the last products with AR "original philosophy" and, in my opinion, they are the best speakers manufactured by Acoustic Research.

AR philosophy was to get crossover frequencies as low as possible to obtain more dispersion thanks to their wonderful dome speakers.

AR 9 was a completely different design. Low and high midrange drivers were different; the 200003 woofer, for the first time in AR history, worked in a different volume from that it was designed for.

I have listened to all these speakers and in my opinion AR 11 and AR 10 pi are AR masterpieces. They are very hard to drive to get their best performances but they are AR best speakers ever.

Luigi 

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To be sure, the 10pi and 11 were the last top-of-the-line bookshelf designs from AR (assuming the extraordinary LST is a "special" speaker, and apart from the standard line), but the original 9 has to be included as a legitimate extension of the AR design philosophy. True, it is a 4-way system, but it shares 3 of its 4 drivers with other AR products - only the midrange dome/semi-horn is new. The superb low-end response of the 9 could not have been achieved in a conventional design - the 2-woofer system, increased cabinet volume, and electrical control of Q is a sophisticated (and EFFECTIVE) approach to bass reproduction that could not be approached by any of AR's previous designs. The crossover points chosen are also very much in keeping with previous design experience, and combine for a dramatically increased output capability while maintaining CONTROLLED dispersion - the 9 was the first AR system to address cabinet reflections and vertical driver alignment & symmetry. This takes nothing away from the 10pi & 11...simply stated, it's doubtful if AR would have produced the 10pi design WITHOUT having previously built the LST, AND it's doubtful that the 9 could have happened without the 10pi and 11 speakers that preceeded it. This sounds like evolutionary engineering progress to me!

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Actually, AR 9 shares only the woofers with previous AR flag ship speakers  as you can see in the engineering files in the library. You can also note the driver differencies only by looking at them. Maybe AR 9 was a more sophisticated and expensive speaker. But in hi-fi more sophisticated and expensive doesn't always mean a better sound!

 As regards AR LST, it also had some important measurement defects that are never mentioned both in anechoic frequency responce and polar diagrams . Infact,  although It had an excellent dispersion,  frequency responce and polar diagrams were  poor and irregular because of constructive and destructive interferences of 4 tweeters and 4 midranges sounding in the same frequency range respectively. Moreover, purists don't like that the same drivers sound in the same frequency range for different reasons: the already mentioned interferences that affect polar diagram and frequecncy responce and especially because  the "same" drivers (midranges, tweeters or woofers) are not perfectly the same, in other words they can't be perfectly identical. They say that the sound is not so clean as when it is a single driver sounding in a given frequency range.

AR LST frequency response in an anechoic chamber was not so smooth as 11's or 10's and Roy Allison did improve a lot this aspect in the successive Allison One he designed few years later. The in-room response,  assessed with third-octave filtered pink noise, showed that bass frequencies were not so good as AR 3a's or 11's or 10's.

Ar 11 and 10 Pi laboratory measurements were much better in any aspect (except dispersion at high frequency also if it was excellent as well) than any previous AR speaker and, at the same time,  they did keep AR classic philosophy both in design and sound.

 Stive F has already mentioned in post #3: "The 11 can be considered the ultimate development of the basic AR 12-inch "bookshelf" speaker. It's response was exemplary. It's smoothness and lack of distortion were unexcelled. Most speakers today would be hard-pressed to match its performance. A pair of AR-11's in good working order is a superb speaker, by any standards." 

Furthermore, the autotransformer use in 10 Pi was an evolution in comparision to LSt's. Differently from the only 6 frequency responses allowed by AR LST, AR 10 Pi autotranformer  allowed 27 different frequency responses!

  I have listened to many AR vintage speakers (2ax, 3a, LST, 11, 10 PI, 9, 91 etc) and I have had the opportunity of comparing them in difeerent circumstances. In my opinion, as already said,  when correctly driven, AR 11 and 10 PI are probably AR best sounding speakers ever, at least in the listening enviorement I've listened all these speakers. The power amplifiers used in these comparisions were very good and famous amplifiers: Jadis 200, Mark Levinson 20.5 and 29, Krell KSA 150s, Krell KSA 50 MKII, Manley  100/240, VTL 75/75, ANTHEM Integrated, Copland 501, Electrocompaniet EC1, Chord.  Unfortunately no one of these very expensive amplifiers is mine. A friend of mine is a Hi-Fi dealer and he (and some other friends) lent me those amplifiers.

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No doubt that AR 9 was

>probably a more sophisticated and expensive speaker. But in

>hi-fi more sophisticated and expensive does not mean a

>better sound.

Well, sometimes it does...like in this case - the 9 has all of the attributes of AR's best bookshelf speakers, PLUS extended low frequency response, greater uniform spl capability, and controlled mid & HF dispersion. Having the vertically aligned drivers at (seated) ear level doesn't hurt, either. Cost-wise, while the 9 was more expensive than AR's top-of-the-line predecessors, it was still real-world affordable, and relatively less expensive than the AR-1 was for its era.

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  • 1 year later...

You mention the AR 58, they made AR78 , AR98LS and AR 9LS. This forum discusses the superb AR9's but what about the updated version, the AR9LS? Was this model an improvement over the 9's? I use the 98LS which I think are just outstanding. If I had had the money at the time I would have gone for the AR9LS but they were twice the price at £1000 in 1982.

My Dad has a pair of AR 3a's. He bought them in 1969. They still have their original foam / cloth? surrounds. I checked them last night and they are still intact. Many years ago I replaced the pots in the back. Should they have new capacitors in the crossover network or any other work done. Any advice would be much appreciated.

Regards Mark

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Mark,

I've written about the history of the 9LS in a previous post, but I don't recall offhand exactly where that post is located.

However, I save all my longer posts as Word docs (I actually write them in Word first, so I can check them for spelling and grammar before I post them), and I've pasted it below. Hope this helps.

(Written Feb 21, 2004):

The AR-9 was introduced in 1978 after a relatively protracted development period. Remember, AR’s model numbering scheme in those days was chronologically sequential, so when the AR-8 was introduced in 1974 and then the 10pi and 11 followed in 1975, it was apparent to sharp-eyed AR-watchers at the time that they had "missed one." In 1976, the 12 and 14 followed (no model 13, for the obvious American-superstitious reasons, just like there is never a 13th floor in a high-rise building in the US). So we were all waiting for the mysterious, secret model "9" to make its appearance.

It finally happened, 2 years later, and boy! What a speaker! So many innovations -- the acoustic blanket, the vertical-alignment of the mid and hi frequency drivers (with a complete, industry-first technical explanation of why it was important to do it that way), the side-firing woofers, a la Allison’s research into the effects of room boundaries on low-frequency power radiation, and more. This was a ground-breaking product that genuinely advanced the state of the art of music reproduction in the home. It was a high water mark for the company, and like the LST in 1972, the 9 sold extremely well despite its high price.

The accolades rolled in form all the magazines and critics. As good and well-respected as the 11 and 10pi were, they didn’t bring AR back to the top spot in the industry’s and the critic’s view. The 9 did, and AR was back, all the way.

Not content to rest on their laurels, AR set about refining and improving the 9. One of the slight defficiencies of the original 9 was that, while the horizontal dispersion was extremely wide and very uniform (thanks to their vertical alignment), AR noted that the 9’s VERTICAL dispersion was somewhat irregular. Vertical dispersion is not as important in a real-world listening room as horizontal dispersion (listeners can easily be scattered 5 or 6 feet horizontally about the listening area, but their ears will always be within 5 or 6 inches of each others’, assuming a normal height chair or sofa and people within a foot in height), but nonetheless, it can affect the near-field tonal quality when standing or sitting, and irregular dispersion will always have some effect on far-field power response.

The 9LS addressed this when introduced in 1982. Their solution with the 9LS was the Dual Dome driver, whereby the 1 1/2" and 3/4" drivers were mounted very close together and driven by the same magnet structure. Having the two drivers that close (within about an inch or so) allowed them to avoid the usual side-by-side response irregularities of conventionally-mounted drivers. Mounting the drivers in this manner meant that the 9LS’s dispersion was consistent and uniform in both the vertical and horizontal planes, yielding a somewhat smoother, more refined sound.

The LS also went from side-mounted 12’s to a forward-facing 12" and an internally mounted 10", outputting through a slot just above the 12" driver. AR claimed this arrangement made the speaker less placement sensitive, while still compensating for the "Allison Dip" effect.

The critical response to the LS was just as enthusiastic as the original 9, maybe even more so. High Fidelity Magazine said the 9LS had "…perhaps the deepest, cleanest, firmest, most natural reproduction we have ever heard." Quite a speaker.

Steve F.

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>When driven well, in my opinion, AR 11 and 10 PI are the best sounding speakers AR has ever made.<

Luigi, it's great to read you again.

Can you tell us (me) what it is you find so admirable about the 10pi/11 sound that seems to be missing in the 9?

Bret

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