Acoustic Research AR8B Speaker System Review

The two-way AR8B is the smallest and least expensive speaker system in the current Acoustic Research line. Like all AR speakers, it is an acoustic-suspension model, and it has a newly designed 6-inch woofer that crosses over at 2,000 Hz to a 1-1/4-inch “liquid cooled” cone tweeter. (The tweeter presumably uses ferrofluid or a similar material to damp and cool its voice coil.) The crossover network has been simplified and its cost reduced by designing each driver to have a natural rolloff outside its operating frequency range. As a result, only a capacitor is needed to protect the tweeter against damage from powerful low-frequency signals. The effective crossover slopes are 12 dB per octave for the woofer and 18 dB per octave for the tweeter.

The drivers of the AR8B are vertically aligned in a cabinet measuring 14-3/4 inches high, 9-1/2 inches wide, and 6-1/4 inches deep (it can also be installed horizontally). The enclosure is finished in walnut-grain vinyl veneer, and its rounded front edges minimize the boxiness of its shape. The system weighs 10-1/2 pounds. The dark-brown cloth grille is retained by plastic snaps, and spring-loaded input connectors in the rear of the speaker accept the stripped ends of speaker wires.

The specifications of the AR8B include a sensitivity of 88 dB sound-pressure level (SPL) at 1 meter with a 2.83-volt input (1 watt into the speaker’s nominal 8-ohm impedance) and a system frequency response with half-power ( — 3-dB) points of 74 and 22.000 Hz. The AR8B has no external frequency-balance or level controls. It is recommended for use with amplifiers delivering between 10 and 75 watts per channel. The AR8B is packaged and sold in pairs. Price: $179.98 per pair.

Laboratory Measurements

Both our room-response and anechoic (FFT) frequency-response measurements of the AR8B showed a slightly depressed output between 4,000 and 15,000 Hz relative to the midrange response. The close-miked woofer response, however, was quite flat, with a maximum output at about 150 Hz; the output fell to — 3 dB at 1,150 and 95 Hz, and it continued downward at 12 dB per octave below the latter frequency. The spliced composite frequency-response curve was flat within ± 1.5 dB from 100 to 4,000 Hz, down by as much as 4 or 5 dB between 4.000 and 15,000 Hz, and up 4 dB at 20,000 Hz (relative to the 1,000-Hz level). The overall response variation between 85 and 20.000 Hz was only ±4 dB. The anechoic axial response as measured with our IQS FFT-analysis system was generally very similar, except that the analyzer’s internal filter attenuated the response somewhat above 17,000 Hz. The tweeter dispersion was very good up to 10,000 Hz, but in the upper part of the next higher octave the response at a 45-degree horizontal angle to the speaker axis was down by as much as 12 to 15 dB.

The phase response of the AR8B was very linear with frequency, resulting in a group delay that varied only about ±0.2 millisecond from 1,000 to 20,000 Hz. The system impedance was between 5 and 8 ohms over almost the entire audio range, reaching a maximum of 16 ohms at the system’s bass resonance frequency of 100 Hz. The measured sensitivity was higher than rated, with 2.83 volts of input producing a 92.5-dB SPL at 1 meter on the speaker axis. The woofer distortion with a 1-watt input was low, increasing smoothly from 0.6 per cent at 100 Hz to 2.8 per cent at 60 Hz. With 10 watts input, the distortion rose from 2.8 per cent at 100 Hz to 15 per cent at 60 Hz.

Comment

Our measurements showed that, within the inherent limitations of its 6-inch woofer diameter and compact overall dimensions, the AR8B is a remarkably good sound reproducer. This was completely confirmed by listening tests. Placed against the wall about 9 feet apart and 28 inches above the floor, our sample pair of AR8B’s filled the room with a sound that totally belied their size and price. Obviously, they cannot play as loudly as many larger speakers or shake the room with their bass output. On the other hand, the natural rolloff of the AR8B’s low-bass output prevents it from generating a lot of audible “pseudo bass” (which is really distortion). We never felt the need to push the speakers to unreasonably high volume levels, perhaps because their sound was so well balanced.

Although it is hardly reasonable, we could not resist making an A/B comparison between the AR8B system and our reference speakers, which cost about fifteen times as much. Strange as it might seem, the similarities between their tonal characteristics far outweighed the differences. This is not to suggest that they are in any way equivalent speakers but only that a flat, reasonably well-dispersed output from 100 to 10,000 Hz is a key to good high-fidelity reproduction, and these two very different systems share that property. Once you have met that basic requirement, it is the refinements—such as extended response at both ends of the frequency spectrum, higher power-handling ability, and different dispersion patterns—that distinguish most speakers from each other and are responsible for much of the price differences between them.

It is not really surprising that AR has made another good speaker—the company has been doing that for nearly thirty years. Nevertheless, the small size and low price of the AR8B make it a very attractive choice for budget-priced systems and installations where space is limited. This speaker proves that there is no need to sacrifice good sound because you don’t have a mansion-sized music room or a $10,000 stereo budget.

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