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....