High-End Studio Monitor Shootout: ATC SCM-300A AND DUNLAVY SC-V

Aug 1, 1999 12:00 PM, John La Grou

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For some years, Millennia Media's remote recordings were edited in the corner of a small room, on smallish monitors. Before long, with annual schedules exceeding 60 remote sessions, a better editing and listening environment was overdue. The construction of an improved working space in 1997 demanded an equally improved monitor system. This is the brief story of our experiences with two exceptional full-range loudspeakers tested at length in our new room.

Before jumping into the loudspeaker review, a little bit should be said about the new room. Starting from the ground up, acoustician George Newburn (at the time with acoustics design firm studio bau:ton, now with his own design group, Studio 440) specified plans for a 6,000-cubic-foot facility that included 9-inch solid concrete walls, acoustic uncoupling of floor, walls and columns, acoustically proportioned sawtooth wall sections, large random-diffusion arrays and thick wool carpet. The room measures 23x29 feet and is designed for a combination of editing, full-range critical listening, multitrack work and future expansion to surround applications.

Our design criteria specified a freestanding full-range monitor system. After spending two years auditioning dozens of large "audiophile" and professional monitors, the search was narrowed to a short list of candidates. Two were brought into the new room for lengthy comparison testing: the British ATC SCM-300A and American Dunlavy Audio Labs (DAL) SC-V.

THE SPEAKERS Both speakers were auditioned in numerous room placements and positions. Final location was determined by achieving the most realistic imaging performance. Speakers were provided at least four feet of separation from walls. (It should be noted here that soffit-mounting the ATCs, something we did not attempt, will result in a 10Hz improvement in LF extension, from -6 dB at 30 Hz as a floor mount system to -6 dB at 20 Hz in soffit mount.)

The ATC SCM-300A system includes a proprietary, stand-alone, 140-pound chassis sporting tri-amplified (275-watt LF, 200-watt MF and 100-watt HF per channel), Class-A-biased stereo amplifiers and ATC-provided speaker cabling. The Dunlavy SC-Vs were driven with a pair of Pass Laboratories 300W Aleph 1.2 mono amplifiers placed behind each speaker and connected with 1-meter lengths of Goertz "MI-2" Alpha Core flat cable.

Playback devices for this test included a G&H Transforms CD transport and Panasonic SV-3900 DAT machine, both feeding AES digital into the Ultra-Analog-based 20-bit Manley Gold Reference DAC. Digital interconnects were Mogami 3080, while Mogami 2549 and MIT Pro-Line cables carried the analog signals; all terminated with gold-plated XLRs.

The Dunlavy Audio Labs SC-V is a four-way, 7-speaker tower (75x15x27-inch, HxWxD) strongly reminiscent of Mr. Dunlavy's former design, the highly acclaimed Duntech "Sovereign"-used in a variety of mastering rooms worldwide. The passive crossover is a first-order design. With narrow dispersion, patented phase and dispersion correction, Wifa drivers and a non-ported enclosure, the SC-V is said to be "designed to reproduce the amplifier's electrical signal as closely as possible." Inputs are heavy-duty, bi-wired five-way binding posts. Various finishes are available. Our demo pair were delivered with furniture-grade light oak veneer. The SC-Vs are provided with matching floor-mount oak veneer pedestals.

Dunlavy's SC-V speaker complement includes dual 12-inch woofers, dual 7-inch low-mids, dual 3-inch high-mids, and a single 1-inch silk-dome tweeter. The SC-Vs weigh in at 305 pounds each. Frequency response is down 3 dB at 22 Hz and 24 kHz, measured on-axis at 12 feet. Nominal impedance is 3 ohms. Price: $16,000/pair.

The ATC SCM-300A is a soffit-mountable, three-way, 4-speaker cabinet (35x36x19-inch, HxWxD) comprising ATC's own Super Linear Magnetic Material speakers, including the company's often copied soft-dome, midrange driver. All speakers are driven directly from ATC's own integrated fourth-order, tri-amplifier system. Heavy-duty terminations are mated to a proprietary interconnection system. Finish of demo units was rubbed black lacquer. Other finishes are available.

The ATC speaker complement includes dual 15-inch woofers, a single 3-inch soft-dome midrange driver, and a single 1-inch tweeter. The company is wont to assert that, though its mid-range driver is often copied, most contemporary copies are largely cosmetic-markedly lacking, as ATC points out, in areas of magnet quality, coil technology and suspension detail. The SCM-300As weigh 225 pounds each. Frequency response is down less than 2 dB at 50 Hz measured on-axis at six feet. Price: $33,899/pair.

LISTENING TESTS A number of audio professionals participated in our listening comparisons. During the non-blind sessions, participants were encouraged to take as much time as possible with their own source material. Subjective evaluation language and certain evaluation parameters were taken from AES Specification AES20-1996 (invaluable guidance for people doing their own speaker listening tests). Subjective opinions were noted in areas such as LF and HF accuracy, timbre balance, imaging, softness/hardness, fullness/thinness and so forth (see table on p. 114).

Though not surprising, one of the most instructive results of these tests is that speaker preference was sharply divided among musical tastes and expectations. Details will follow, but the over-simplified "executive summary" is this:

Audio professionals involved predominantly with pop/rock music generally preferred the ATC system, and those largely involved with acoustic and classical music generally preferred the DAL system. The reasons behind this will become clear as we look more closely at each speaker's performance and personality.

Perhaps the most obvious difference between these two monitors is their maximum SPL level. It's here where ATC fields a commanding advantage over DAL. A single ATC 300 cabinet will deliver an astonishing 121 dB SPL at less than .3% THD (with an additional 10 dB of headroom available!), an important consideration for loud pop music monitoring.

Due to a combination of active efficiency, patented and proprietary driver design (read: robust), and dual 15-inch drivers (vs. the DAL's dual 12-inch drivers), the ATCs are able to develop a massive amount of crystal-clean, room-pounding program material. These speakers offer a truly exhilarating experience. My advice? Wear effective ear protection around wide-open ATCs. Of course, as ATC points out, these speakers are not primarily intended for absolute SPLs-such "unlimited head-room," representatives of the company say, "translates into absolute clarity, openness and confidence with all types of source material."

Though the DALs don't play as loud as the ATCs, many listeners agreed that they did have an advantage in overall timbre accuracy, especially in the mid- and high-frequency regions. Comparing LF timbre purity between the two loudspeakers was not as clear-cut. Some sensed the ATC low-frequency drivers as "faster" and more "tactile" than the DAL, describing a more immediate "presence" of LF program.

I personally found that various low-frequency material seemed better suited to one speaker or another, with neither speaker proving consistently superior-again lending credence to the premise that no monitor system is optimal for all production goals.

For reasons probably related to the DALs' narrow dispersion, first-order crossover and phased tower orientation, their imaging characteristics are quite sensitive-much more so than the ATCs'. Slight changes in the DAL's width and toe angle can lead to significant changes in imaging.

The most convincing DAL imaging was achieved with a very wide 18-foot spacing and toe angle facing directly at the listening position. The DAL's narrow dispersion also demanded that the listener stay within a relatively small listening window. Although this is ideal for a single person playback arrangement (mastering suite, etc.), I'm not convinced of its relative merit in a playback environment where even a small group of people must congregate to listen critically. Speaker-to-listening position distance measured 12 feet (creating a triangle measuring 18x12x12 feet).

By contrast, the ATCs were less prone to image variation within a much larger range of width, toe and listening window. The positioning that seemed to capture ATC's ideal depth and focus was a width of 12 feet and a toe angle of about 10Degrees inward. Speaker-to-listener distance was 12 feet, creating an equilateral triangle of 12x12x12 feet.

Over a course of weeks, audio professionals charted their perceptions of each loudspeaker with program material well known to them, scoring 1 to 10 in various performance categories. Not surprisingly, both speakers scored high in all categories, with none receiving a score less than 7. Overall, the DALs were given nominal preference in areas of overall timbre balance and on-axis imaging performance while the ATCs took preference in LF accuracy and off-axis image performance.

Both loudspeakers were considered suitably "full, spacious and clear." And while the DALs were perceived on average as "somewhat soft," the ATCs were considered by some as "somewhat hard." Keep in mind that many of these distinctions can be quite subtle. The scoring chart presents a complete summary of panelists' subjective testing.

As recordists of mostly classical music, we (Millennia) found particular benefit in the DAL's "difficult" imaging characteristics. No longer were our spaced omni recordings giving us the acceptable sonic positioning we had realized on wider dispersion, less surgically precise speakers. The DAL's narrow dispersion exposed weaknesses in center images, while pulling heretofore center-left and center-right images even farther toward the left/right extremes.

As we adjusted our recording techniques to increasing ratios of coincidence, vs. wide/ambient wash, including higher percentages of true center and near center detail, the DALs revealed heretofore unrealized sonic subtleties-improving the sense of realistic presence and depth in our recordings.

Such changes to recording technique have so far retained a convincing image on less critical and wider-dispersion monitoring systems, as well. With this single improvement in tools, we've come a few steps closer to finding that elusive acoustic balance of panoramic precision, ambient realism and timbre accuracy.

In summary, I will say without hesitation that these are two of the finest loudspeakers available, yet they remain worlds apart in design philosophy-and neither system gave us everything we desired. If there was just some way to morph the best attributes of both. It's like that old saying "price, quality, delivery-pick two," except, in this case, it reads: "image, dynamics, timbre-pick your subtle trade-offs."

That said, let it be clear that what these speakers do, they do exceptionally well. One Sacramento, Calif., studio owner who participated in the test was so thoroughly impressed by the ATCs that he purchased an SCM-300 system for his own studio. At $25,000 per system, this is clearly not an impulse purchase but one that addresses a clear market need. Not surprisingly, both speakers have already been installed by numerous highly regarded audio facilities worldwide.

ATC, distributed by Precision Systems Integrated, 305 River Road., Tullytown, PA 19007; 215/949-8300; fax 215/949-8400; www.psintegrated.com.; www.atc.gb.net.

Dunlavy Audio Laboratories, 5050 List Drive (F), Colorado Springs, CO 08919; 719/592-5940; fax 719/592-0859; www.dunlavyaudio.com.






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