Design Acoustics DA-30 Speaker System Review

The Design Acoustics DA-30 speaker system is the first new product to come from that company since its recent acquisition by Audio-Technica U.S., Inc. The DA-30 is a three-piece system (a format that is currently enjoying some popularity) consisting of two small DA-10 “satellite” speakers and a single DA-20LF bass module that operates below 160 Hz. The DA-20LF can be located almost anywhere in the room, although in most cases best results will be obtained if it is in the same general area as the satellites.

The DA-10 satellites, each of which is 11-3/4 inches high, 7-3/8 inches wide, and 5-1/2 inches deep, are attractive wooden units with an oiled walnut finish, beveled front edges, and a black grille. Each is a miniature two-way system, with a 5-inch acoustic-suspension “woofer” and a 1-inch dome tweeter, crossing over at 2,500 Hz. The DA-10 can operate as low as 80 Hz and like the DA-20LF, is available separately as well as part of the DA-30 system. Switches in the rear of the DA-10 can be set to increase its midrange and treble output by about 3 dB. A bracket on the back simplifies a wall-mounting installation, but their size and appearance gives the user a wide latitude in locating the DA-10’s.

The DA-20LF bass module is 16 inches square and 20 inches high, with a walnut-finish wooden top and black grilles on its four visible sides. However, its surfaces are solid behind the grilles, since the single 12-inch woofer is located in the bottom, facing downward. Short legs support the DA-20LF 1/4 inches from the floor, allowing the bass to radiate through a 1-1/4-inch slot around the periphery of the cabinet. This is called “Constant/Variable Proximity Loading (C/VPL)” by the manufacturer. One of the advantages claimed for it over conventional bass speaker designs is that the woofer loading is determined primarily by the design of the system, with minimal influence by the immediate room surroundings. Of course, placing the DA-20LF against a wall or in a corner will enhance its bass output—as it would that of any speaker. However, because of the low crossover frequency, midrange output will not be affected by the DA-20LF placement. In addition, the beveled front edges of the DA-10 satellites are designed to minimize diffraction effects that could interfere with their imaging qualities.

The DA-20LF, like the DA-10, is an acoustic-suspension design. It contains a single 12-inch dual-voice-coil driver whose left- and right-channel voice coils are wound concentrically on a single 2-inch-diameter form. Little stereo information is contained in the lowest octaves, so that mixing the lows causes no sacrifice of directionality (there is some disagreement on this point, but our own experience tends to support it).

Since the DA-20LF contains the system crossover network, both amplifier outputs are connected to input terminals under the bass module, and wires are run from there to the DA-10 satellites. A second set of input connections and a toggle switch permit the crossover network to be bypassed for biamplified operation. The Design Acoustics DA-30 has a nominal impedance of 4 ohms and is rated for use with amplifiers having outputs from 35 to 250 watts per channel. Price of the complete DA-30 system: $595.

Laboratory Measurements

The total power-frequency response of the DA-30 system, measured in the rear of the room, was impressively smooth and flat. After correcting for room absorption, the response of the DA-10 satellites was flat within ±2.5 dB from 300 to 20,000 Hz. The dome tweeter of the DA-10 had excellent dispersion, with the left and right speaker curves beginning to diverge slightly above 7,000 Hz but with no more than 5 dB of difference between them up to 20,000 Hz.

The close-miked woofer response was measured at the radiating “slot” between the DA-20LF and the floor (a check at the cone showed that the response was identical at both places). In the “bi-amp” mode, which bypasses the crossover network, the woofer response was flat from 80 to 200 Hz, rising to +3 dB in the 55- to 70-Hz range and dropping at 12 dB per octave below 50 Hz. In a biamplified system, the bass crossover should be set no higher than 200 Hz, although one might safely go lower than the 160 Hz used in the DA-30 system.

Through the DA-20LF crossover network, the response was flat to about 150 Hz and fell off at 18 dB per octave above that frequency. Splicing the bass and mid/high curves was relatively unambiguous, and the combined response was within ±3.5 dB from 45 to 20,000 Hz. There was an output dip of about 5 dB centered at 150 Hz, perhaps due to the physical configuration of the speakers for our measurements. The DA-10 units were supported in the clear, about 3 feet from the wall and 4 feet off the floor. In that configuration the small woofers would receive the least reinforcement from the room boundaries.

The switches on the back of the DA-10 modified its output beginning at about 1.000 Hz, boosting it about 1 dB at 3,000 Hz and a maximum of +5 dB above 5,000 Hz. The bass distortion, measured at the same place we used for the response measurement, was between 0.5 and 1 per cent from 100 Hz to below 50 Hz at a 1 watt input. It rose to 1.8 per cent at 40 Hz and 7 per cent at 30 Hz. Increasing the power to 10 watts yielded distortion readings of about 2 per cent down to 50 Hz, 5 per cent at 40 Hz, and 12.6 per cent at 30 Hz. The system impedance was about 4 ohms from 60 to 6,000 Hz, rising to about 10 ohms in the 20- to 40-Hz range. At high frequencies (above 1,500 Hz) the impedance was 10 to 16 ohms. The DA-30 system had unusually high sensitivity for an acoustic-suspension design. Driving it with 2.83 volts of pink noise in an octave band centered at 1,000 Hz, we measured a sound-pressure level of 90 dB at a 1-meter distance from the grille of the DA-10.

The response of the DA-30 was also measured under quasi-anechoic conditions with our Indac FFT analyzer at distances up to 15 feet and at various angles to the axis of the speakers. Since this measurement does not smooth or average the narrow-band response fluctuations of the speaker, its contour did not match that of the averaged power-response curve. Even so, the overall variation was typically within ± 6 dB from the lowest frequency displayed by our analyzer (180 Hz) to the 17,000-Hz upper limit imposed by the internal low-pass filter of the analyzer. When we turned the DA-10 unit through 45 degrees to check its dispersion with this technique, the principal change was a drop of output above 12.000 Hz or so compared to the 17,000 Hz achieved by a head-on measurement.

Comment

The Design Acoustics DA-30 delivered a strikingly balanced, uncolored sound in our listening room. It may seem strange to describe a lack of color or emphasis as “striking,” but compared to most speakers that is the way we reacted to it.

We have used three-piece speakers before, with results that have ranged from fair to excellent, but the blending of the DA-20LF with the DA-10 satellites was exceptionally effective. In fact, no one could suspect from the sound that a common-bass module was present at all (it was usually hidden behind other speakers or furniture in the room). On the other hand, one could not imagine how the tiny DA-10 units could generate the room-filling bass that was present when the program called for it. Quite an effect!

Our favorite speaker configuration was with the DA-10s on their backs on a narrow shelf along the front wall of the room about 30 inches from the floor and facing upward. In this position, which gives very nearly an omnidirectional response horizontally, we preferred to use the “ + 3-dB” switch setting to compensate for high-frequency absorption in the acoustic-tile ceiling. This arrangement makes possible what we think of as an “invisible speaker system,” which happens to be the preferred format in our home. To achieve invisibility without some sacrifice of sound quality is a noteworthy achievement, and we were impressed with how well the Design Acoustics DA-30 coped with the challenge. In another room, we heard the system in a more conventional configuration, with the DA-10s on pedestals, well in the clear, and facing the listeners. This gives the sound an appealing airiness, as well as the kind of imaging that many people seem to prefer (our taste runs toward a somewhat more diffuse sound field).

The high sensitivity of the DA-30 also sets it somewhat apart from most comparably priced high-quality systems, since it can develop wall-shaking sound levels at any audio frequency when driven by a good 30-watt-per-channel amplifier. In fact, we were never tempted to push it to its limits with a 200-watt amplifier, not because of fear for the speaker’s survival, but rather because of concern about overload of our auditory sensibilities.

It is easy to understand the growing popularity of the three-piece speaker system, which provides an optimum blend of quality and flexibility to say nothing of value for the money. In addition, the DA-30 happens to be a most attractive system (if its components are set up to be visible) as well as sounding at least as good as a pair of very fine conventional “box-type” speakers in the same price range.

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