Acoustic Research AR-2a (1960–1965)
A ten-inch sealed-box woofer, two cone tweeters, and the AR-3's dome super-tweeter bolted on top - the workingman's acoustic-suspension classic.
Overview
The AR-2a is the AR-2 with the top octave fixed. Acoustic Research took its established AR-2 - a ten-inch acoustic-suspension woofer with a newly improved cone, paired with two five-inch cone tweeters - and added the 1¾-inch dome-type super-tweeter already proven in the AR-3. That one driver is the whole story. The AR-2 had earned a reputation in both home and professional use, but the dome got it closer to the flagship's air. The company's own announcement, as it ran in Audio (January 1960, p.83), called that super-tweeter AR's most nearly perfect driver. It claimed the dome's behavior in the high treble conformed more closely to the ideal than any of the company's other drivers did in their ranges.
The low end is the part that still holds up. The ten-inch woofer uses the acoustic-suspension principle in its purest small-box form. The cone's suspension is so compliant that it can't supply its own restoring force, so the sealed cabinet's internal air pressure does the work instead. The cone rides on air rather than mechanical springs, and per AR's own literature the small enclosure isn't a compromise - it's necessary for optimum performance. That seal is also the restoration weak point. Open the cabinet to service a driver or crossover and you've broken the air spring. It has to go back together airtight or the bass goes soft and flabby.
Above the woofer, the two five-inch cone tweeters hand off to the dome super-tweeter at 7500 cps, with the lower crossover set at 2000 cps. That high handoff keeps the bulk of the midrange with the cone drivers and gives the dome only the top octave, which AR described as covering the entire range of musical instruments. The dome uses a very small, stiff, hemispherical diaphragm as a direct radiator, and that buys the off-axis behavior. AR's published figure was ±1½ dB on-axis from 7,500 to 20,000 cps, with usable response maintained both horizontally and vertically off-axis. It isn't airy by modern standards - the top octave rolls away gently - but it avoids the spit and sting that made so many period tweeters tiring.
The AR-2a is a four-driver system: one ten-inch woofer, two five-inch cone tweeters, one dome super-tweeter. AR recommended amplifiers of 20 to 40 watts, so this is a speaker that wants a clean 30 watts, not a monster. The cabinet measured 13½ inches high by 11½ inches deep. AR finished it on all four sides except on the pine model. Prices ran from $109 in unfinished pine to $128 in oiled walnut, with mahogany and birch at $122.
Sound character is warm and forgiving. Jazz trios, vocal records, and acoustic material come across with body and ease. Dense modern mixes can feel a touch veiled up top. It's not an analytical speaker, and it was never meant to be. High Fidelity (March 1970, p.9) later framed the whole AR-2 series as a standard of high-fidelity performance where cost requirements made technical compromise necessary. The AR-2a was the best of that series, the version that pushed the compromise furthest back.
Key Features
Ten-Inch Acoustic-Suspension Woofer
The woofer is the reason these speakers still command attention. A compliant suspension plus a sealed box means the air inside the cabinet supplies the restoring force, so a modest enclosure can produce bass without a port to tune or a reflex alignment to drift. The AR-2a used a newly improved cone over the original AR-2, and the design's reputation for clean low end without boom comes from that. Restoration note: the seal is the design. Refoaming a woofer without re-sealing the cabinet properly undoes the very thing that makes the speaker work.
1¾-Inch Dome Super-Tweeter
Borrowed directly from the AR-3, this is the driver that separates the AR-2a from the AR-2. AR's literature described it as the most nearly perfect of its drivers, and the published ±1½ dB on-axis tolerance from 7,500 cps to 20,000 cps supports the claim on paper. The small, stiff hemispherical diaphragm as a direct radiator keeps the response usable off-axis in both planes. A pair with intact, working domes is the thing to pay for.
Dual 5-Inch Cone Tweeters and the 7500 cps Handoff
Two five-inch cone units carry the upper midrange and lower treble, crossing to the dome at 7500 cps. That's a high crossover by any standard, and it's deliberate. It keeps the critical midrange in the cone drivers' domain and lets the dome handle only the top octave, where its small diaphragm is happiest. The lower crossover sits at 2000 cps. The result is a coherent power response across a wide listening area rather than a narrow on-axis sweet spot.
Sealed Cabinet, Four Finishes
Finished on all four sides except the pine version, the AR-2a cabinet measured 13½ inches high by 11½ inches deep. Finishes and prices: unfinished pine at $109, mahogany or birch at $122, oiled walnut at $128. The four-side finishing means the speaker was designed to sit in the open, so it's the version to hold out for if the pair will be displayed rather than shelved.
Historical Context
The AR-2a landed in 1960, after Acoustic Research had already upended the speaker market with the AR-1 and brought acoustic suspension down in price with the AR-2. The AR-2a was the refinement: AR-2's woofer and cone tweeters, AR-3's dome super-tweeter, at a price well under the flagship's $203 - $225. AR sold it as a low-cost acoustic-suspension system with a super-tweeter. By the company's own accounting, 78,481 AR-2a units were manufactured over the model's five-year guarantee life.
That guarantee was five years and covered parts, labor, and reimbursement of freight charges to the factory. AR published the return numbers to back it up. Of those 78,481 units, 671 were either returned under guarantee or repaired at AR's stations in New York, Los Angeles, or San Francisco: less than nine-tenths of one percent. The company even ran ads walking through individual repair cases, including a $3.95 check sent to reimburse one owner's shipping.
By 1965 the AR-2a was superseded. AR introduced the AR-2ax - described in its own advertising as a new version of the AR-2a with an improved midrange speaker - and sold $15 conversion kits so existing AR-2a owners could update their speakers to the new configuration. The AR-2a was a transitional design, the point where the AR-2 line got its top octave sorted before the midrange got its own rework.
Collectibility & Value
The AR-2a trades in a devoted but narrow market. The five-year run means survivors turn up often enough that buyers can afford to be selective, and the $109 - $128 original spread is a useful guide to which finish you're looking at. The dome super-tweeter is the value center. It's the AR-3 part, and a pair with original, working domes is worth meaningfully more than one with substitutes or dead units. Cabinets finished on all four sides (everything but pine) are the ones to hold out for if the speakers will be on display.
These are not plug-and-play vintage speakers. Sixty-plus years on, the acoustic-suspension seal and the woofer surrounds are the first things to check, and the crossover capacitors are due for replacement on any unrestored pair. Buyers should expect to re-seal cabinets, inspect the woofer suspension, and verify the dome tweeters before trusting them with serious amplification. The sub-one-percent return rate says the design was sturdy. It doesn't say the foam was immortal.
Market Value
┌──────────────────────────────────────────────────────────────────────────┐ │ ACOUSTIC RESEARCH AR-2A Nov 2026 │ ├──────────────────────────────────────────────────────────────────────────┤ │ High $678 Latest $678 │ │ Median $245 Trend — │ │ Low $15 Volume ~2/mo │ ├──────────────────────────────────────────────────────────────────────────┤ │ $700 ┤ │ │ │ . .│ │ │ │ │ $400 ┤ │ │ │ │ │ │ .. . . │ │ │ │ │ $0 ┤. .. │ │ ├─────────────────────────────────────────────────────────────────│ │ vol │█ ▄▄ ▄▄ ▄ ▄ ▄ ▄│ │ └─────────────────────────────────────────────────────────────────│ │ 2026-02 2026-04 2026-06│ └──────────────────────────────────────────────────────────────────────────┘
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