Acoustic Research Spirit 162 Speaker System Review

Acoustic Research’s new Spirit series of loudspeakers consists of six models, ranging from minispeakers and bookshelf-size units to the top-of-the-line Model 162, a columnar three-way system measuring 36-5/8 inches high, 9-1/8 inches wide, and 13-3/4 inches deep. The AR 162 is designed to be floor standing, but it can be placed on a low stand or base if desired.

Like all AR speakers, the Spirit 162 uses acoustic-suspension woofers. A pair of 8-inch polypropylene-cone drivers, mounted one above the other, share a common enclosure with a volume of 1-1/3 cubic feet. Above them is a 6-inch polypropylene-cone midrange driver in a separate enclosed volume of ¾ cubic foot, and at the top is a 1-inch treated-cloth-dome tweeter with ferrofluid cooling. The specifications do not list the crossover frequencies but claim a frequency response of 45 to 22,000 Hz at the — 3-dB points and a relatively high sensitivity of 91 dB sound-pressure level (SPL) at 1 meter with an input of 2.83 volts. The rated impedance of the system is 4 ohms, and it is recommended for use with amplifiers delivering from 10 to 175 watts per channel.

According to AR, the midrange driver has been designed with a natural high-frequency rolloff that complements the tweeter’s range and eliminates the need for a low-pass crossover element between it and the tweeter (which does require its own high-pass filter to prevent burnout from excessive low-frequency input). The low-frequency and mid/high-frequency sections of the system are brought out to separate pairs of input terminals in the rear of the cabinet, normally joined by metal links. By removing the jumpers, the system can be operated in a biwired or biamplified mode.

The rigid design of the cabinet is illustrated by the front speaker baffle, which is laminated from two panels of medium- and low-density particleboard to form a highly rigid, damped speaker board about 1-1/2 inches thick. The speaker has no conventional grille frame, avoiding the common effect of diffraction and reflections from the frame that color the sound. Instead, an acoustically transparent cloth grille is stretched over the front and fitted into a slot around the perimeter of the baffle board. To further minimize reflections, all the speaker mounting bolts are covered to give a smooth acoustic transition from the drivers to the baffle surface.

The cabinet is available finished in either walnut or black-ash wood-grain vinyl. Each speaker weighs just over 43 pounds. Price: $1,199 a pair.

Lab Tests

Acoustic Research recommends placing the Spirit 162 speakers at least 1 foot in front of a rear wall and 2 feet from a side wall. We put them about 2 feet in front of the rear wall and 4 feet from the side wall, toed in slightly toward the center of the room.

The averaged room response of the two speakers was generally smooth and flat, although there were a couple of peaks of 2 to 4 dB between 700 and 2,000 Hz. The close-miked woofer response (the two drivers had essentially similar responses in their designed operating range) reached a maximum at 85 Hz, falling off above and below that frequency. The woofer response overlapped smoothly with the midrange response and room curve to form a composite frequency-response curve flat within ± 4 dB from 55 to 20,000 Hz.

Quasi-anechoic response measurements with the IQS FFT analyzer confirmed the presence of the midrange peaks and the general contours of the overall response curve. The response curves measured on-axis and 45 degrees off-axis showed that the frequency response did not change materially over that angle at frequencies up to 10,000 Hz, although the two curves diverged rapidly above that frequency. The phase-shift linearity was good, with a group-delay variation of less than 0.2 millisecond from 1,500 to 20,000 Hz.

The system’s impedance modulus (its numerical value) was among the lowest we have measured on a speaker, reaching a minimum of 2.9 ohms at 60 Hz (its DC resistance was 2.7 ohms). The impedance varied between 2.9 and 7 ohms over the frequency range from 20 to 1,500 Hz and reached a maximum of 11.5 ohms at 3,500 Hz. Although the system’s average, or “typical,” impedance was not far from 4 ohms, it might present a difficult load to some amplifiers. We also found a strange behavior in the impedance-phase plot, which reached — 180 degrees at 20 Hz but remained between ± 30-40 degrees from 200 to 20,000 Hz. In the woofers’ range, from 20 to 200 Hz, there were also a number of sharp phase discontinuities suggestive of cone resonances, although no corresponding effect appeared in the impedance-modulus plot. Both speakers gave identical results in this test.

The system’s sensitivity was even higher than rated, with a 93-dB SPL measured at 1 meter with a pink-noise input of 2.83 volts. We measured the woofer distortion at a drive level of 2.0 volts, corresponding to a 90-dB SPL. From a maximum of 4.5 percent at 20 Hz, the distortion decreased to 2 percent at 50 Hz, 1 percent at 72 Hz, and between 0.3 and 0.5 percent from 100 to 200 Hz. At a constant 100 Hz, the distortion decreased from 18 percent with an input of 20 millivolts to a minimum of 0.6 to 0.7 percent from 1 to 2 volts and rose to about 2 percent at 7 volts (corresponding to a midrange SPL of about 100 dB).

In addition to its high sensitivity, the Spirit 162 was able to handle very large short-term power inputs without distortion. At 100 Hz, the woofer cone hit its suspension limits with a “knock” at a single-cycle input of 620 watts into its 2.9-ohm impedance. At 1,000 and 10,000 Hz, the amplifier clipped before speaker distortion became obvious, at respective inputs of 1,320 watts into 5 ohms and 1,500 watts into 4.4 ohms.

Comments

The AR Spirit 162 had a distinctive sound of its own, especially in side-by-side listening comparisons with several other speakers we had on hand. It generally favored the bright, or crisp, side of the acoustic scale, with a “forward” character that seemed to be associated with its emphasis in the 1,000-Hz region. Perhaps because of this quality, its lower registers frequently did not seem as audible as one might expect from its driver complement and size.

Much of this “recessive bass” effect was illusion (like everything else in hi-fi reproduction), since program material with a significant bass content was reproduced quite satisfactorily. Nevertheless, the system’s specifications as well as our measurements suggest that its designers favored high sensitivity over a strong lower-bass response (there is a fundamental tradeoff between these qualities). In a bass-shy listening room this could be a disadvantage, but in a fairly warm room (acoustically speaking) the speaker should be very much at home. We were never aware, in our relatively dead room, of any lack of bass except in comparison with other speakers that had a deeper bass extension. On the plus side, the Spirit 162 was virtually free of the chasteness that most speakers impart to male voices.

As with any other speaker, we strongly recommend that the AR Spirit 162 be auditioned before purchase, preferably in a room not too different (acoustically) from its intended environment. Also like any other speaker, it will sound different in every room in which it is placed, but because its bass performance is unusually sensitive to room acoustics, the kind of room you have could be a more significant factor than usual in its selection.

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