Boston Acoustics Model 360 Speaker System Review

While most dyed-in-the-wool audiophiles are willing to accept the necessity of large, highly visible, and often expensive speaker systems for high-quality home music reproduction, there are many situations in which such speakers are unacceptable. Obviously, many people cannot afford to spend thousands of dollars for their speakers, a small room cannot accommodate a pair of bulky speaker enclosures, and even though a number of very compact speaker systems are available, they are not always compatible with a room’s decor—or capable of the desired quality of reproduction.

A somewhat similar situation exists in commercial establishments such as restaurants and stores. Here, high fidelity is rarely a requirement, since the speakers are used only for background music, but physical unobtrusiveness is likely to be even more important than in a home environment. The usual solution is flush-mounted ceiling speakers. Even reasonably satisfactory listening quality, let alone a semblance of high-fidelity sound, is uncommon in such installations.

In the last couple of years, several hi-fi speaker manufacturers have announced “decorator” lines of speakers designed for flush mounting in walls or ceilings. Though conceptually much like their commercial counterparts, they provide a sound quality that will not offend the sensibilities of any but the most critical listener. The Boston Acoustics Model 360, part of the company’s Designer Series, is a good example of the genre.

The Model 360 is a two-way system with a 6-1/2-inch woofer and a 1-inch copolymer dome tweeter—a new version of the tweeter used in the finest Boston Acoustics systems. The drivers and crossover are mounted on a rectangular plate designed to fit into a cutout in a wall or ceiling. Mounting hardware is supplied. The external trim plate, which contains a removable perforated-metal grille, measures 12 x 8 inches and is 5/8 inch deep; the depth of the woofer behind the wall is only 3-1/4 inches. The shallowness of the speaker allows it to be installed in any standard wall built on 2 x 4-inch studs.

The physical characteristics of the Model 360’s woofer were chosen to provide satisfactory bass performance when the driver is enclosed in the volume between the studs of a typical wall. Of course, the final bass response will also be affected by the placement of the speaker on the wall relative to other room-boundary surfaces. The diaphragms of both drivers are waterproof, so that the speakers can be installed in moist environments such as kitchens and bathrooms or even on boats. The grille and trim of the Model 360 are finished in matte white, but they can be painted any color to suit the room decor.

The specifications of the Boston Acoustics Model 360 include a frequency response of 48 to 20,000 Hz ±2 dB, a nominal impedance of 8 ohms, and a sensitivity of 90 dB sound-pressure level (SPL) at 1 meter with a 2.83-volt input. It is recommended for use with amplifiers rated between 5 and 60 watts per channel. Price: $350 a pair.

Lab Tests

For our tests, the Boston Acoustics 360’s were mounted in simulated walls, each 24 inches wide and 72 inches high, constructed of plywood on both sides of a framework of 2 x 4-inch studs. These walls approximated the acoustic properties of a room-wall installation. Each speaker was located 60 inches from the floor and near the left edge of its enclosure, and the two enclosures were about 48 inches apart. The enclosures were built by Boston Acoustics for its demonstration room at the 1988 Summer Consumer Electronics Show in Chicago.

The averaged room response of the two speakers was smooth and flat, with a total variation of ± 5 dB from 600 to 20,000 Hz. The close-miked woofer response was flat within 4 dB from 62 to 1,000 Hz, and it spliced easily to the room curve to form a composite frequency-response curve varying ±3 dB from 55 to 20,000 Hz. Although the crossover frequency is not stated in the specifications, our measurements suggest that it is in the vicinity of 2,000 Hz.

The minimum system impedance was 5.5 ohms at 200 Hz, with a maximum of 18 ohms at 70 and 2,200 Hz. By the usual criteria, the speaker’s nominal impedance should be rated at about 6 ohms instead of 8 ohms. The measured sensitivity was 87 dB SPL at 1 meter. The bass harmonic distortion with a 4-volt input (equivalent to a 90-dB SPL) was just over 1 percent at 100 Hz and rose smoothly to 3.2 percent at 70 Hz and 9.7 percent at 50 Hz. The distortion was almost entirely third-harmonic. In our pulse power tests, the woofer began to emit rattling sounds with an input of 72 watts (at 100 Hz). Although some waveform distortion was visible on an oscilloscope when the input reached about 25 watts, the effect was not always audible.

Our quasi-anechoic FFT response measurements confirmed the smoothness and range of the system’s frequency response. On the speaker’s axis, a sharp 6-dB dip in output was evident at 8,000 Hz, although this was virtually undetectable in the room response. The group-delay variation was less than ± 0.2 millisecond from about 500 to 23,000 Hz.

Comments

The flat, wide-range frequency-response rating of the Boston Acoustics Model 360 led us to expect a musical, reasonably uncolored sound from the test units, and we were not disappointed. Comparisons with conventional speakers, all of them far more expensive, confirmed that the Model 360 is a high-quality speaker. Granted, it cannot match the low-bass output of most good component speakers, but down to 60 or 70 Hz it holds its own with many of them. Furthermore, the flatness of its bass response, with a rise of only about 2 dB around 150 Hz, made its sound pleasantly free of tubbiness or boominess on voices, one of the most common speaker aberrations.

The spatial qualities of wall-mounted (or ceiling-mounted) speakers are quite different from those of free-standing models, especially those designed to be placed several feet in front of a wall. Nevertheless, these Boston Acoustics speakers make it possible to have high-fidelity sound in rooms where conventional speaker cabinets are undesirable. Furthermore, their near invisibility can be a major advantage in many installations.

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