Oct 20, 2004 7:25 PM, By Michael Cooper

A RETURN TO STUDIO MONITORS

I would hazard a guess that most studio engineers will not recognize the D.A.S. name, as the Spanish company’s last studio monitor was produced roughly 20 years ago. Established in 1970, D.A.S. began as a manufacturer of studio monitors before changing its focus to produce loudspeakers for sound reinforcement applications. The company has returned to its roots with the introduction of its Monitor line of near- to midfield recording and broadcast studio monitors. The Monitor-8s and their smaller sibling, the Monitor-6s, are the first offerings in the expanding product line. The larger Monitor-8s are reviewed here.

At $459 each ($918/pair), the Monitor-8s are modestly priced, so I was completely surprised by what I heard when I first auditioned these superb passive monitors in my control room. In short, I was completely blown away. The Monitor-8s are world-class monitors offered at a bargain-basement price.

First Look
Straight out of the box, the Monitor-8s are beautiful to behold. The heavily radiused side panels are fashioned from exotic Iroko plywood, adding rigidity and visual contrast to the black, 15mm-thick MDF cabinet. This reinforcement minimizes coloration from panel vibration. The top and bottom edges of the cabinet are not radiused. Cabinet dimensions (with a vertical orientation) are 16.5x11x11.5 inches (HxWxD). Each cabinet weighs 28 pounds. The monitors are not magnetically shielded.

Behind the detachable black-cloth grille are two drivers: an 8-inch polypropylene woofer with a rubber surround and a 1-inch soft-dome, ultrafine aluminum-diaphragm tweeter. The low-frequency driver’s oversized motor structures and cast-aluminum chassis promise improved efficiency and impulse response. The tweeter’s voice coils are Ferrofluid-cooled for maximum power handling and improved linearity.

The tweeter sits behind a protective fine-mesh metal grille. Both the tweeter and grille are inset in a Linear Quadratic Spherical™ waveguide, the curved shape that reportedly reduces diffractive effects at high frequencies. (The radiused side panels make a similar contribution.) The result is wider, more uniform imaging and less distortion due to comb filtering. The waveguide also increases the tweeter’s sensitivity.

A circular bass-tuning port is on the rear panel directly opposite the high-frequency driver. Also on the rear panel are two binding posts that provide power amp connections; these accept only bare wire. Two M6 (metric 6) female mounting points are located on the bottom of the cabinet that allow the monitors to be anchored to a flat stand with a downward tilt.

Specs
The Monitor-8s are rated at 125-watt RMS power, 250W program power and over 500W peak power handling capability; D.A.S. recommends an amplifier rated at 125 to 250 watts at 8 ohms. The specified peak SPL at full power is 116 dB, and I found a stereo pair of Monitor-8s to be plenty loud when powered by my 150-watt Hafler P-3000 Trans•nova amp. On-axis sensitivity (1-watt/1 meter) is a respectable 89 dB SPL.

The Monitor-8s’ frequency response is specified as 38 to 33k Hz (with no tolerances given). D.A.S. recommends you place the Monitor-8s four inches from a wall for added reinforcement of bass frequencies; a supplied chart shows the frequency response one would ideally expect with such placement. The response is 3 dBs down at 55 Hz and 2 dBs down at 20 kHz, with impressive linearity in between both extremes. (These measurements were made using a 1W swept sine signal at 1 meter with the Monitor-8s in a half-space anechoic environment. (For more information, see “On the Bench.”) The crossover point for the 12dB/octave Linkwitz-Riley passive crossover is 3 kHz.

Testing 1, 2, 3
For reasons specific to my control room’s acoustics and ergonomics, I placed the Monitor-8s about two feet from the nearest wall. D.A.S. recommends you orient the monitors vertically and the nonconcentric arrangement of the drivers suggests this for optimal imaging. However, ergonomics directed me to orient the monitors horizontally in my control room. Nevertheless, stereo imaging was spectacular.

The Monitor-8s were installed into my Acoustic Sciences Corporation ATTACK Wall, a modular arrangement of cylindrical bass traps designed to soffit speakers and neutralize the acoustic signature of the front of the control room. Because the Monitor-8s are ported in the rear, the sidefill ASC Studio Traps™ and top Monitor Trap™ for each speaker were removed to allow low frequencies to vent back into the room to the mix position.

For my critical listening tests, I listened to many of my recent mixes and favorite outside CD releases that I was intimately familiar with, spanning rock, pop, country, techno, grunge, folk and Celtic music styles. I was immediately struck by the Monitor-8s’ rock-solid stereo imaging, profound sound field depth, open clarity and articulate detail. It was as if a veil had been removed from the mix, revealing hidden subtleties. The silky-smooth high end was sweet yet eminently articulate, without a hint of stridency. Vocals sounded startlingly realistic, brimming over with unfettered nuance. Chimes and strummed guitar sounded downright palpable, with transients accurately and sweetly reproduced. Overall, the mids and highs were beautifully balanced and smooth.

The only downside of how the Monitor-8s performed in my setup was that lower bass frequencies—below roughly 80 Hz—were reproduced rather weakly. No doubt this could have been improved by placement closer to a wall. And it must be said that most close-field monitors suffer the same weak bass, if often with a somewhat lower cut-off. Switching in my Tannoy PS-88 active subwoofer (a discontinued model) completely corrected the imbalance, and the Tannoy perfectly complemented the Monitor-8s. In fact, the Monitor-8s’ relatively high-bass roll-off kept interference with the sub to a minimum, creating a more seamless coupling of the two systems.

With the sub added to the mix, drums sounded extremely realistic. Stick and kick drum beater strikes were beautifully defined and the traps’ timbres perfectly balanced. Heaven.

I found the Monitor-8s to be very nonfatiguing without sounding even slightly dark or veiled. Of course, the timbre was understandably darker outside of the sweet spot, but the balance was nevertheless easily workable.

Conclusions
Engineers looking to use the Monitor-8s as their main speakers will want to add a subwoofer, especially if they can’t place the cabinets four inches from the wall, as the manufacturer suggests. But even without a sub, “mid-room” placement still affords an extremely accurate reference for checking stereo imaging and the spectral balance from the mid-bass frequencies on up. This has always been a near-field monitor’s raison d’être, and the Monitor-8s deliver in spades.

The Monitor-8s are one of the most detailed and transparent monitors I’ve ever had the pleasure to work with. Imaging and depth are downright superb. As an added bonus, the monitors are really fun to listen to without sacrificing accuracy.

With its first studio monitor offering in 20 years, D.A.S. has hit a grand-slam home run over the centerfield fence. These are world-class monitors at a dirt-cheap price, and there’s no way that I’m going to relinquish them. My check is in the mail!

DAS Audio, www.dasaudio.com.

ON THE BENCH
The D.A.S. Monitor-8s’ Transfer function was measured in Metric Halo Labs’ SpectraFoo Complete using an Earthworks M30 mic placed one foot from the woofer-tweeter mid-point, a Millennia Media HV-3 mic pre and Apogee Rosetta A/D converters. The monitors were installed into an ASC ATTACK Wall with the cabinet roughly two feet from the nearest wall and were powered with an Hafler P-3000 Trans•nova amp for the tests.

Figure 1 shows the Monitor-8s’ frequency response (green trace) to be approximately 3 dBs down at 78 Hz and dropping off rapidly below 50 Hz. Over most of its response range, the Monitor-8s are flat to within +1/-3dB tolerances, the most noticeable exception being a hump centered around 135 Hz. Linearity is especially impressive above approximately 1.25 kHz. The response is down only a fraction of a dB at 18 kHz. Data on the graph above 18 kHz is not meaningful due to incoherence with the source signal (as indicated by the red trace in Fig. 1).

Figure 2 shows the Monitor-8s’ phase vs. frequency performance in SpectraFoo Complete. Two snapshots, represented by the green and yellow traces, were taken. The signal’s phase does not actually flip 180° at 2 kHz (yellow trace) or at 2.5 and 8 kHz (green trace), but the display traces merely wrap around (i.e., +180° = -180° phase). Data around the flip points and above 18 kHz are not meaningful.

The green trace shows the expected linear progression of phase vs. frequency for a noncoaxial design. Between approximately 2.5 and 6.3 kHz, the green trace shows the Monitor-8s to produce minimal change in phase shift. That is, there is no additional group delay (no abrupt transition in phase shift) around the 3kHz crossover point, and all frequencies within the 2.5 to 6.3kHz band are arriving at roughly the same time. This is as it should be in a good crossover design.

Because the green trace wraps around very close to the crossover point and makes it hard to accurately see what’s going on there, the yellow trace snapshot was taken with the source channel delay offset by one sample from that value that the green trace was derived from. This modulates the data away from the wraparound at the crossover point for a better look. Although the one-sample offset introduces its own phase shift (i.e., it compounds the Monitor-8s’ phase shift and therefore produces inaccurate absolute data), the yellow trace is useful in that its linearity confirms that there are no discontinuities in phase shift around the 3kHz crossover point.

Figure 3 shows the Monitor-8s’ impulse response in SpectraFoo Complete. Especially considering the nonconcentric orientation of the drivers, the impact and decay response are outstanding. An examination of the spectral history (not shown here) in SpectraFoo Complete reveals that the second impact spike (broader and lower in amplitude, noted by the pointer in Fig. 3) was produced by the woofer and occurs later than the tweeter’s initial spike.