A "Super Value" Speaker from AR
Acoustic Research AR-28s loudspeaker system, In wood cabinet with vinyl finish. Dimensions: 11 3/4 by 21 1/2 Inches (front), PA inches deep. Price: $125. Warranty: "full," five years parts and labor. Manufacturer: Teledyne-Acoustic Research, Inc., 10 American Dr., Norwood, Mass. 02062.
ACOUSTIC RESEARCH'S newest line of speakers is aptly titled the Super Value series: three models ranging in price from $90 to $150, with the AR-28s occupying the middle slot. The AR-28s, which closely resembles the company's Model 25 (test report, March 1980). has a moderately tall, narrow enclosure and two drivers-an 8-inch woofer/midrange and 1-inch dome tweeter-aligned vertically on the baffle. There are spring-loaded connectors in a recess on the rear of the enclosure, but no driver level controls. AR has chosen to effect economies in the least important area, putting tone balancing where we think it belongs: on your preamp or receiver.
In tests at Diversified Science Laboratories, the sensitivity came in at a 90-dB sound pressure level for a 2.8-volt in put (equivalent to 0 dBW or I watt into 8 ohms). For an acoustic suspension sys tem of relatively small volume, that is remarkably high. Moreover, the AR-28s is no slouch at handling high power inputs.
It easily accepted our maximum continuous input of 28.3 volts (equivalent to 20 dBW or 100 watts into 8 ohms) and with stood inputs of more than 60 volts peak. 6 3/4 dB higher.
The impedance curve is smooth and well controlled. AR specs the speaker at a nominal 6 ohms with a minimum of 4.5 ohms. DSL's measurements confirm this, pinpointing the 4.5-ohm minimum at 5.5 kHz. In the musically active midrange, however, impedance values remain higher. With its high efficiency, high power-handling capability, and smooth impedance curve, the AR-28s constitutes an excellent match for just about any amp. (AR suggests one with a power out put between 15 and 100 watts.) But some caution would he in order when paralleling two pairs from a single amp, where the 5-ohm midrange minimum translates to an impedance of 2.5 ohms.
At loud playing levels (100 dB SPL ), the second harmonic predominates in the distortion products and averages about 2% from 80 Hz to 10 kHz. The harsher-sounding third harmonics are very low, averaging 1/2% over the same range. At the saner playing level of 85 dB SPL, second harmonics decrease dramatically to about 1% and third harmonics are also lower.
In its owner's manual, AR suggests experimentation in speaker placement for optimum tonal balance. Though the AR-28s, like other speakers in the Super Value series, can be used as a genuine bookshelf model, DSL's tests (confirmed by some of AR's own comments) indicate a somewhat smoother and deeper response when the speaker is placed on the floor against a wall. Our data, including the graph, reflect this placement. Frequency response is unusually smooth virtually flat through the midrange and upper treble, with a small peak at about 1.6 kHz. Bass response remains strong down to 63 Hz.
In listening tests, auditioners were unanimous in appraising the AR-28s as a pleasant, accurate performer. Our sample pair easily dealt with extremely dynamic records played at very high levels: the deep, powerful timpani, for in stance, from the "Hall of the Mountain King" movement of the Peer Gynt Suite (Telarc 10048) emerged with lots of drama, albeit lacking in the visceral wallop that a larger system can afford.
Stereo imaging is superb-broad and with surprising depth. The word "detailed" cropped up often in our listening sessions: the speaker is noteworthy for its ability to discriminate among delicate instrumental timbres in the most complex orchestral pieces.
With the AR-28s. Acoustic Research continues to improve a genre for whose creation it is largely responsible.
In a competitive market, the manufacturer has chosen to persist in its thrust toward more accurate sound-even in its lower-priced models. By comparison to more dramatic speakers, this model might. in fact. sound a hit reticent (its high end, for instance, refuses to over state the importance of the triangle in a symphony orchestra), but this is one loudspeaker that will satisfy the discriminating listener long after the others have lost their charm. In an age of spiraling inflation, the AR-28s emerges as a speaker even a struggling musician could afford-and admire.
ROOM RESPONSE CHARACTERISTICS
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(High Fidelity, Jul. 1981)
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