Acoustic Research AR Classic Reference Manual

Seth=L

Seth=L

Audioholic Overlord
I am transposing a copy of a limited print manual for the Acoustic Research Classic series speakers. To my knowledge there is no place where this document is available online. I have only a rough copy provided to dealers as standardized manuals for this series were apparently not printed due to the limited production of the speakers and the company changing it's gears. My reasons for doing so: First, so that someone searching for information regarding the AR Classic series will find it and it will be use to them. Second, to bolster collectible value by increasing awareness of a very rare and great overall product. It's the duty of collectors to bring something to the table they've discovered if it is something that is really worth looking at. In the end our ears will make the verdict.

Licensing belongs to Acoustic Research formerly a division of Jensen Corp. The manual has been edited as many pieces of information are irrelevant (such as AR's contact information that is no longer in service).

AR CLASSIC

HIGH RESOLUTION LOUDSPEAKER SYSTEMS

OWNERS REFERENCE MANUAL edited from original by Seth=L

SRA SERIES

Congratulations finding a wonderful pair of AR Classic loudspeakers! We sincerely hope that your classics will add to your musical fulfillment for years to come. We designed the AR Classic with one primary goal: be faithful to the music, because, after ll, isn't that what this is all about? So welcome to the AR extended family! And if you need our help that's sad because we are no longer the company we were when these speakers were designed and manufactured.


Bringing your new found Classics into your finely tuned sound system with change your relationship with your system. We want that change to be for the better. We want you to get the most out of your investment in your new AR Classics, so we've prepared the following installation guide. We'll try to accomplish a few things.

First, we'll discuss the technology we've used to develop the Classics so that you can better appreciate your investment in fine sound. Second, we'll lead you through the process of unpacking and positioning your Classics in your listening room. Third, we'll describe the several options available for hooking up your Classics to their driving amplifier(s).

Acoustic Research has combined measurement and listening in developing the AR Classic line. After all, this approach isn't really new to AR. We've been developing innovative solutions to the problems of home music playback since 1954. We've given the world the acoustic suspension woofer, dome midrange and high frequency drive units, and liquid cooled drivers. Each innovation improved music reproduction in a tangible and practical way and evolved direction from two principles: First, the products must set a standard not previously achieved, or they must perform far beyond similarly priced competitors. And second, no matter how advanced the technology may be, music is always the essential purpose and ultimate measure.

We hope you find your new AR Classics achieve these goals.

Technical Overview

Classic SRA Series speakers systems are all build around one of AR's core technology modules, called the Symmetrical Radiation Array (SRA). This "building block" came about after AR's engineering staff conducted extensive reviews of all aspects of loudspeaker design and manufacture. Having enjoyed great success with the novel "mid over tweeter" drive unit topology employed in the Holographic Imaging Series, placement and integration of drivers assumed top priority.

What the designers were seeking was controlled, uniform dispersion within a moderately wide listening window, as distinct from the ultra-wide window offered by Holographic Imaging systems. In addition to controlled dispersion, the designers were seeking better integration between mid-band drivers and tweeters. The result is the SRA, featured in the Classic series of home loudspeaker systems.

The SRA consists of four major pieces, one 1" soft-dome tweeter, two midrange drivers and a crossover. Apart from one change in driver size, the SRA is identical in all Classic systems, from the 18 to the 36. The SRA places the midrange (or mid-bass) drivers above and below the tweeter in a vertical array, at positions dictated by the crossover.

This topology creates a virtual point source, i.e., all sound appears to emanate from one point (or acoustic center). This has long been the goal of loudspeaker manufacturers and there have been many interesting approaches to the problem, co-axial, co-incident etc. The Acoustic Research SRA overcomes most of the problems of a point source without recourse to horns, or waveguides.

The output from the midrange drivers must blend seamlessly with that of the tweeter (and with the woofer(s) in the three way systems) so the crossover must divided the signal electrically, and combine acoustically.

The design of the crossover considered the tree drivers as part of the circuit, and extensive computer modeling was employed to replicate the dynamic performance of the system. The network used in Models 18 through 36 cannot be split for bi-wire or bi-amp purposes as, in extensive listening tests, separating the networks degraded the performance. This is largely due to the low current demands of the SRA in 3-way configurations. Classic Model 12 is a 2-way SRA system, with low frequency extending down to well below 50Hz, some 2 1/2 octaves below the regular SRA cutff point of 200Hz. This does require high current and so the Model 12 is the only SRA system which the mid-bass units can be separated from the tweeter. All other Classic SRA sepakers provide for bi-wiring / bi-amping at the crossover point from the woofer(s) to the mid-band driver (200 Hz).

AR Classic Models 26, 30 and 36 employ dual woofers loaded in an Acoustic suspension configuration. Acoustic suspension is the low frequency loading method employed in the SRA series as it still offers the most linear method of producing low frequencies, irrespective of amplitude. The two woofers are used in a vertical array, but are separated by the SRA. Placing one woofer at the top of teh cabinet and one at the bottom reduces the chance of exciting nodes in the listening environment as the path lengths to any given point very rarely coincide. This reduces the upper bass congestion prevalent in many floor standing speakers, while retaining the weight and transient impact present in live music.

The drive units are all new designs from Acoustic Research [note from Seth=L: this means that finding replacement drivers will be difficult since these speakers were produced for only one year before AR changed their entire operation]. All the cone drivers employed in the Classic series feature cast-baskets, rather than the more common, and significantly cheaper, pressed steel type. This reduces vibration from the drive unit itself, providing a more stable environment for the moving parts. The tweeter is an all-new soft cloth dome design with 1" (2.54 cm) voice coil with liquid cooling for improved power handling. The same tweeter is used in all AR Classic series speakers, and like all components in all AR systems, was selected only after extensive listening.

The enclosures that house all this technology are designed to be as inert as possible. Trapezoidal in footprint, and with a sloping top, the cabinets are heavily braced internally and are finished in high quality real wood veneers. The trapezoidal shape helps to reduce standing waves within the enclosure and provide increased rigidity. The front panel (baffle) is as slim as possible for any given drive unit size and is heavily reinforced. This is to reduce early reflections in the mid to high frequency domain. All Classic SRA models are equipped with removable spikes and removable protective grilles.

In order to get the best from your new Classic loudspeakers, please take a few minutes to read the following instructions. These will help you get your system up and running, and offer some suggestions on system upgrading to improve overall performance levels.

Unpacking Your Speakers

Warning! These speakers are heavy! Some models may need two people to lift and move them.

Having opened the carton on the correct end, fold back all four flaps. Then turn the carton over, so that the open end is on the floor. Lift the carton off the speaker, then lift the speaker off the endcap and remove the protective wrapping. Do not discard the packing as it will be useful should you need to transport your speakers at some future date. Please take the time to complete and return the warranty card. [note from Seth=L: this information is clearly not pertinent but I left it in anyway for those that may still have the original box or maybe a NIB set of these speakers. My advise to those that have NIB models is to hold on to them and wait until the market is right if you don't wish to keep them.]

To be continued....
 
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Seth=L

Seth=L

Audioholic Overlord
Installation of your Classic Speaker System

AR Classic Models 26, 30 and 36 are floor standing models and are supplied with carpet piercing spikes. They may also be used with the Acoustic Research sound Basis, which are optional accessories available through your dealer. Models 12 and 18 require elevation for optimum performance. This can be achieved by use of the AR sound basis 12 or 18. If you wish to use another type of stand we suggest the use of rigid metal framed stands which can be filled with sand and/or lead shot. These should be equipped with carpet-piercing spikes or hard rubber feet for use on hardwood or tiled floors. For use with the Classic Model 12, the height of the stand should be 12" (30cm), for the Model 18 a stand of 8" (20cm) should be employed.

To install the spikes, lay the speaker on its back and screw the spikes into the threaded inserts in the base of the cabinet. In addition to the sonic benefits of anchoring the enclosure to Mother Earth, the threaded spikes can also be used to level the speaker.

Suggested Positioning


AR Classic systems are designed to provide a wide listening seat and maintain correct placement of instruments. However, like human beings and animals, speakers need room to breathe, therefore the wall facing your listening area should be relatively free of obstructions. The illustration provides information on MINIMUM distances from boundaries, there is no maximum. There are maximum limits to the distance between the loudspeakers, and the distance from speakers to listening area. This will vary from room to room according to the type of construction, layout, furnishings etc. but a good starting point is to make the distance between the speakers equal to the distance between speakers and listener. We strongly recommend you start with the speakers firing straight out as shown in the diagram.

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With the speakers positioned in your listening room, now we can proceed with connecting them to your system.

Please Note! Loudspeakers are mechanical devices that need to be 'burnt in". Therefore we do not recommend that any changes to the system be made for one week after installing your Classics. This period will enable you to familiarize yourself with the sound of your new system, and allow the speakers at reasonable time to burn-in. If you wish to accelerate the burn-in, leave the speakers playing at a moderate level for 24 hours. Then you can settle down for some serious listening.

Connecting Your Speakers

WARNING!! DO NOT MAKE CONNECTIONS WITH EQUIPMENT SWITCHED ON!!

All Classic speakers are equipped with high quality gold plated terminals which will accommodate cables terminated in many forms. They will accept spade lugs, 4mm banana plugs, pin plugs, and bare wire. Please note that there are two sets of terminals, linked by a gold plated jumper bar. This permits performance improvements at a later stage.

Level I Conventional Mode

To wire in the conventional mode, leave the gold jumper in place. Then connect one of the + (red) terminals to the + (red) terminal of your amplifier and one of the -(black) terminals to the - (black) terminal on your amp. Repeat for second speaker.

Level 2 - Bi-Wire Mode

This is our preferred method of connection as we have found it to yield significant sonic benefits. In order to bi-wire your Classic speakers, you will require two extra lengths of speaker cable. Please note we recommend SPEAKER cable - not lamp cord or electrical flex. First, the jumper bars must be removed. To do this, unscrew all four terminals until the jumper bares become loose, slide them outwards to remove them. Repeat for each speaker. Large Classic models all have metal terminal posts. To remove the jumper bar, the terminal lock nuts must be completely removed. The jumper bars slide off the posts, then replace the terminal lock nuts.

Removing the jumper bars separates the high frequency (tweeter) section from the low frequency (woofer) section. With the jumper bars removed connections must be made to all four terminals on each speaker or portions of the audio spectrum will be noticeably absent.

Connect the woofer + (red) terminal to the + (red) terminal on your amp and the woofer - (black) terminal to the amplifier - (black) terminal. Then connect the tweeter + (red) to the same + (red) terminal on your amp and the tweeter - (black) terminal to the same amplifier - (black) terminal. The speaker will now have one conductor running from each terminal and there will be two conductors connected to each of your amplifiers terminals. Repeat for second speaker. Most good quality amplifiers will hold two spade connectors, or stacking banana plugs may be used.

An alternative method to bi-wiring is possible if your amplifier has provision for two sets of speakers and you only intend to use one pair. Follow the connection instruction for bi-wiring but at the amplifier connect the woofer lets to one set of outputs and the tweeter leads to the other. If your amplifier has speaker switching, ensure both speaker systems are switched on at your amplifier.

Level 3 - Bi-Amp Mode

This is more complex than bi-wiring and requires the use of two stereo amplification stages in addition to the double cable runs required for bi-wiring. If you wish to use the bi-amp mode we recommend the use of two identical power amplifiers as gain structures and phase response are rarely identical even with the same manufacturers range. If you use amplifiers of differing power outputs, conventional wisdom recommends the use of higher powered amplifier to drive the lower frequency section. However, if you have two power amplifiers, we recommend listening to each one in the conventional manner (level 1). This will help you determine which is the more detailed amplifier. This is the one we recommend for driving the tweeters, as the ear is much more critical of the upper registers. It is not necessary to use an active crossover to bi-amp the Classic speakers as full crossover networks are built into each enclosure.

In order to bi-amp your Classics, you will need to remove the jumper bars as detailed in the Level 2 - Bi-Wiring. You also need to provide signal to the two power amplifiers. This can be done by splitting the output of each channel of the pre-amplifier. Use a "Y" connector, or better still, a custom-made lead. Some pre-amplifiers do provide two outputs, so adapters will not be required, simply double up on the interconnects. Having connected the pre-amp to the power amplifiers, then connect the amplifiers to the loudspeakers in the following manner. Observing the polarity convention (red to red, black to black) connect the woofer (lower terminals) of the left speaker to the left output of the low frequency amplifier. Repeat for right channel. Then connect the tweeter of the left speaker to the left channel of the high frequency amplifier. Repeat for the right channel. Check that all the connections are correct, with no loose strands that could might cause shorting. Then switch on and enjoy the music.

To be continued....
 
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Seth=L

Seth=L

Audioholic Overlord
Acoustic Research AR Classic Reference Manual continued...

Positioning for Performance

You will know fairly quickly whether the speakers are tool close to a boundary, as the upper-bass with be a little heavy. This is due to reflection from the side or rear walls. Move the speakers into the room and listen again. According to the wall treatment of the listening room, the amount of reflected energy will vary. Windows, glass picture frames, patio doors and mirrors are highly reflective and may make the sound overbright at the listening position. In this case turn the speakers inward slightly, toward the listening position. Do not turn them in too far or the stereo image will collapse. Unfortunately, there are no short cuts in this process, as all rooms are different, so it is a process of trial and error. When you feel you have found the best position, then and only then, should you consider making other changes in the system. If not you may end up with a permanent fix for a temporary condition.

We hope you get many years of music pleasure from your purchase, because that is what we designed them to deliver. For almost forty years, AR has manufactured quality audio components at competitive prices. AR was the first audio company to offer a 5 year warranty and can still service speakers made in the early fifties, so the longevity of your purchase is assured.

Thank you for choosing AR.

Maintaining the Appearance of Your Loudspeakers

Some AR loudspeakers are finished with a hand-rubbed, furniture grade real wood veneer. They should be maintained as a fine piece of furniture. To protect their appearance, we suggest periodic application of a high-grade furniture polish follow the manufacturer's directions for use.

The cloth grilles can be cleaned by periodic gently vacuuming using an upholstery attachment or crevice tool. This should be done with the grills removed from the loudspeakers to protect the drive units.

Here are some additional pictures of the Classic 18s. After the pictures is a roster of the speakers produced for the Classic series. You will notice that there are discrepancies between the list and the manual. I can conclude only that I have seen at one point or time for sale online the Classic 26 and the Classic 30. I have seen the Classic 18 discussed as well as the 26 and 30. I have never seen another Classic series model discussed or sold anywhere else. This could mean that some models never made it to production while AR was trying to decide what to do, or that some are much rarer than others. I hope this will help someone or give them an idea of what they are looking at if they happen to come across one of these models.

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Seth=L

Seth=L

Audioholic Overlord
If anyone has any questions about AR's Classic series speakers please post them on this thread and I or someone else will attempt to answer the question as best as possible. Please do not send PMs so all questions and answers will be viewable by the public.
 
Q

qquickk

Audiophyte
Order crossover

What order crossover is the Classic model 12? I have a pair that are in very good condition, almost flawless. They don't match up well in my small room. I'll let them good very reasonably if some one wants to pick them up. Zip 61114.
 
Seth=L

Seth=L

Audioholic Overlord
What order crossover is the Classic model 12? I have a pair that are in very good condition, almost flawless. They don't match up well in my small room. I'll let them good very reasonably if some one wants to pick them up. Zip 61114.
I wish I knew about the crossover in the Model 12. I may be interested in them. Rockford is probably a 5 hour drive from here. What finish are they?
 
Q

qquickk

Audiophyte
Classic 12

Black finish, email for pictures. they won't let me post email address, but I have them advertised on rockford craigslist. I found out they are third order cross at 2K Hz.
 
G

gdewey

Audiophyte
Is $300 a good price for Classis18ss in 'brown finish', near excellent, with blown woofers?
My first post.
Just found this site...
 
Seth=L

Seth=L

Audioholic Overlord
I would say not. The classic 18 is a good speaker system, however it is fussy about placement and has a limited range off axis. Factor in the near impossibility of finding factory replacement woofers (these speakers were made for a very short period of time before the company was re purposed) but without sophisticated tools and know how finding a suitable replacement would be difficult as well assuming no driver specifications can be found to draw from.
 
B

basel

Audiophyte
Thank you for your excellent work Seth=L! Jean-Luc taught you well! ;)
I thought I would ask the following questions for your advice. Any help would be greatly appreciated.

My family finally pulled my old Classic 30's out from their catacomb of storage, and the two lovely beauties are now on their way across the Atlantic to me. Therefore your hard work has ignited a new flame in my world, as I'm pretty sure my original manual is long gone... so thanks again for this awesome post! I am a working musician, and I currently use JBL LSR 4328P powered monitors to mix with. I was wondering, how good would the Classic 30's be for monitoring purposes? (i.e. how flat is their response?)

I used to power my AR Classic 30's with MTX-Soundcraftsmen MOSFET A400 amp & P100 preamp combo (also from the early 90's), but those babies were nowhere to be found. I am now on a tight budget, so I was thinking of getting the NAD C326BEE integrated stereo amp to power them with ($550). At 4 ohms it is rated to deliver a peak of 150W per channel (they call it "IHF Dynamic Power" whatever that acronym stands for!...) while they list it as having <0.009% THD and +/- 0.2dB across the 20-20k Hz range, so it seems to be a relatively quiet and flat integrated amp. Do you agree that for the time being, this is a good budget amp for these phenomenal loudspeakers? Or any alternate recommendations for a similar budget range?

Because I honestly remember them as being the best sounding loudspeakers I'd ever heard, though that was some fifteen years ago now! Thanks again mate, excellent effort on this transcription!
 
S

Sebastian Napoli

Audiophyte
I have a pair of near mint condition ar classic 26's... I love them - love their handling of mids and highs- really sweet sounding no harshness even in the highest pitches. Any idea of what these speakers are worth? I dont think id ever get rid of them but id love to know thier worth. I paid 700 but i cant help but feel they have to worth more. Once again thanks for all of your efforts here because thier is literally no info anywhere about these.
 
walter duque

walter duque

Audioholic Samurai
Seth=L since you seem to be an expert when it come to AR speakers maybe you can help me out, I did own a few AR's in past. AR3A's, LS3 or LS7 I am not sure they where 3 AR3A's in one cabinet. I did own a pair of AR's in the early 80's that stood about 5' tall with side firing woofers, do you recall that model by any chance???
 
Seth=L

Seth=L

Audioholic Overlord
Seth=L since you seem to be an expert when it come to AR speakers maybe you can help me out, I did own a few AR's in past. AR3A's, LS3 or LS7 I am not sure they where 3 AR3A's in one cabinet. I did own a pair of AR's in the early 80's that stood about 5' tall with side firing woofers, do you recall that model by any chance???
Old thread, but I believe that is the AR9.

 
R

Rich Bradley

Audiophyte
Seth, do you know anything about the crossovers in the Classic series? I have a pair of Classic 30's which I have had for about 5 months, and they sound great at this point, but I have not opened them up to look at the crossovers for the types of capacitors and whether it would be worthwhile to replace any.
 
Seth=L

Seth=L

Audioholic Overlord
I'm not sure what quality or caliber of capacitors were used, sorry.
 
R

Rich Bradley

Audiophyte
Thanks,
If I get around to pulling a woofer to see what the cross over looks like I will take some pics and post.
 
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