





A.R. Loudspeakers
(Early production)
Acoustic Research, Inc. ("AR") was founded in 1952 and incorporated on August 10, 1954 by Edgar Villchur (inventor, writer, audioelectronics researcher and teacher) and his student Henry Kloss. AR1 In 1954, Acoustic Research introduced the small AR1 bookshelf loudspeaker that used the acoustic suspension principle developed by the company cofounders. The acousticsuspension woofer (or air suspension woofer) uses the elastic cushion of air within a sealed enclosure to provide the restoring force for the woofer diaphragm. This principle revolutionised the loudspeaker industry in the late fifties because it provides a way to design a small speaker system (instead the refrigerator sized cabinets previously used to get halfway decent bass) with effective and more linear low frequency response. It will results very clean reproduction of deepbass tones by drivers with relatively small cones (e.g. smaller than 1216 inches in diameter) not mounted in a horn or other increased coupling at low frequencies enclosure. The acoustic suspension enclosure has one disadvantage: it is less efficient as the conventional and more large speakers (which in the fifties were driven by 1020 watts tube amplifiers). Instead of 10 or 20 Watts, this new loudspeakers needed a more powerful amplifier. The Model AR1 was showed in September, 1954, at New York Audio Fair. The 12 woofer, designed and built by AR was coupled initially with 8 high frequencies driver produced by Altec and based on Western Electric design,. Both units were in a sealed ^{3}/4inch thick plywood cabinet filled with fiberglass. Lately the high frequencies driver was replaced by one cone driver for midhigh frequencies.
Dimensions: 25" x 14" x 11" Weight : 50 lbs The speakers should be used in horizontal position.
Almost contemporarily AR introduced the AR1W (a woofer only speaker), intended to be used with a separate high frequency unit.
AR1 speaker input ( I cant explain it)
AR2 In 1957, AR introduced a smaller, less expensive, acoustic suspension system, the Model AR2. The original AR2 was a 2way using two 3.5" cone drivers for the midhigh frequencies. These were mounted in a plastic 'cup' located above the woofer. This cup angled the drivers slightly toward one another. One smaller diameter woofer (10) Dimensions: 24 x 13 ½ x 11 ½ The speakers should be used in horizontal position.
AR3
In 1958 AR introduced the model AR3, which used the AR1s acousticsuspension woofer in conjunction with the first commercially available hemispherical midfrequency driver and highfrequency tweeter, the socalled dome tweeter. The AR3's 2inch dome middriver and 1^{3}/_{8}inch phenolicdome tweeter were the first directradiator dome drivers commercial manufactured. Dome diaphragms had been previously used, but these diaphragms were always used with horntype and compression drivers, never as directradiator, widedispersion dome tweeters.
Dimensions: 25 x 14 x 11 The speakers may be used in horizontal or upright position.
AR2A
A bit later than AR3 (1959), Acoustic Research introduced the AR2A. The AR2a added the AR3 tweeter to the existing AR2 system.
The AR2A technical specifications are available on request.
AR3 ST (1958) Supertweeter only to add to the AR3 or AR2A speakers. It converts an AR2 to the equivalent of an AR2A or can be used to extend the high frequency range of an AR1 (from the original AR advertisement) Dimensions : 11 ½ x 6 ½ x 5 ^{1}/_{8}"
AR3 T (1958)
This is the tweeter system of the AR3 (midrange and supertweeter). It converts an AR1 or an AR1W to the equivalent of an AR3. (from the AR original advertisement) Dimensions : 14 x 7 ^{7}/_{8} x 6 Ό It should be used in horizontal position.
AR4 (1964)
In 1964 AR introduced this small twoway loudspeaker with an 8" woofer and small cone tweeter (3.5). Dimensions: 19 x 10 ½ x 9 ½
AR4X Introduced in 1965, this loudspeaker has the same 8 woofer but a smaller cone tweeter (2.5), crossed very low [1200 Hz], so failures are common. The tweeter level of AR4xs is controlled by a single continuous knob on the back of each speaker. The potentiometers tend to corrode over time, eventually silencing the tweeters, although the tweeters are in working order. Dimensions : 19 x 10 ½ x 9 ½
AR3 A The AR3 was later (1967) replaced by the AR3A, with 1.5 dome midrange and a dome tweeter reduced in dimensions (1), for better mid and high frequency dispersion. It has too different crossover point (IIRC about 450 Hz). AR3 and AR3A have the same woofer (12) in the same sized box. Successively the tweeter was changed from the earlier 1 hard coated fabric dome to a .75 pressed paper dome. Dimensions : 14 wide, 11.5 deep, 25 tall and weigh approximately 53 pounds. The speakers should be used in upright position.
Schematics, specifications and original AR3A brochures are available on request.
AR2AX (1969) The dual midtweeters of the AR2A were replaced with a single midfrequency unit (3.5 cone). The tweeter was upgraded to the improved .75" paper dome tweeter. In early 2ax's were used the same "pot magnet" 10 woofer as the later 2a's, but this was successively replaced with a square ceramic magnet woofer of the same dimension that would serve in many AR models through the 70's and 80's. The cone of this new woofer was lighter and stiffer, with much stronger midrange output. Two 3 ohm resistors were wired in series with the midtweeter unit, to compensate for the change. Crossover frequencies : 1400 Hz, 5000 Hz Dimensions : 24 x 13.5 x 11,5
High and mid controls.
AR5 (1968 or 1969) 10 woofer, 1.5 mid dome driver and 0.745 dome tweeter. Midrange and tweeter units are identical in performance characteristics to those of the AR3A. (from AR original brochure). Dimensions: 24 x 13.5 x 11.5
AR2X (1970) Twoway speaker like his predecessor AR2.It has 10 woofer with treated cloth surround and 2.5 cone midhigh frequency unit. Dimensions : 24 x 13.5 x 11.5
(Sorry, no pictures are available) 
From the original AR1 advertisement
AR1 bookshelf loudspeaker (1954)
AR3 Schematics and original brochures are available on request.
Left: Early version (2.5 cone tweeter). Right: later version (2 cone tweeter)
LINK
http://totalaudio.tistory.com/entry/AcousticReserchAR스피커의분류와역사그리고시리즈별형태모습들 (AR4X early, middleage and late version)
The AR2AX schematics are available on request.

A.R. early models
Model 
Introd. 
Ways 
Woofer 
Midhigh 
Midrange 
Tweeter 
Dimensions 
Weight (Lbs) 
AR1 
1954 
2 
12 
Altec 8 driver A.R. cone 


25 x 14 x 11 
50 
AR1W 
1955 
1 
12 





AR2 
1957 
2 
10 
Two 5 cone 


24 x 13.5 x 11.5 

AR3 
1958 
3 
12 * 

2 dome 
1 ^{3}/_{8} dome 
25 x 14 x 11.5 
52 
AR3ST 
1958 
1 



Supertweeter 
11.5 x 6.5 x 5 ^{1}/_{8} 

AR3T 
1958 
2 


dome 
dome 
14 x 7 ^{7}/_{8} x 6 Ό 

AR2A 
1959 
3 
10 

Two 5 cone 
1 ^{3}/_{8} dome 
24 x 13.5 x 11.5 
36 
AR4 
1964 
2 
8 
3.5 cone 


19 x 10.5 x 9.5 
16 
AR4X 
1965 
2 
8 
2.5 cone 


19 x 10.5 x 9.5 
18.5 
AR3A 
1967 
3 
12 * 

1.5 dome 
1 dome 0.75 dome 
25 x 14 x 11.5 
53 
AR5 
1968 
3 
10 

1.5 dome 
0.75 dome 
24 x 13.5 x 11.5 
39 
AR2AX 
1969 
3 
10 

3.5 cone 
0.75 dome 
24 x 13.5 x 11.5 
36 
AR2X 
1970 
2 
10 
2.5 cone 


24 x 13.5 x 11.5 
33 
* In AR3 and AR3A series AR called the woofer a 12", but its really a unique 11" size all its own.
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