I recently completed construction of a mixing room based upon designs by Ethan Winer and Wes Lachot. The room is 21 ft long, with an 11 ft front wall, 15 ft rear wall, and 8 ft ceiling. A space 4 ft high by 8 ft wide was reserved on the rear wall behind mix position for diffusion. I had planned to use Primacoustic's Razorblade diffusors, which are similar to RPG's popular QRD 734 units. Primacoustic's ongoing effort to secure a new Razorblade manufacturer forced my attention elsewhere. Since my drywall is hung on resilient channel, I'd already had concerns about hanging several 105 lb panels on structure unintended for load- bearing. I next considered RPG's Omniffusor.
At Winter NAMM 2006, Auralex announced the pArtScience line of acoustic treatments designed by Russ Berger, including the SpaceArray diffusor. A comparable product to Omniffusor, SpaceArray boasted differences that made it seem ideal for my application. Each 2 ft square SpaceArray panel is hand-built from very lightweight, but strong, Paulownia wood. Combined weight of eight panels is under 40 lbs-a quarter of the weight for a similar arrangement of Omniffusors, and well under half the weight of a single Razorblade. It didn't hurt that SpaceArray's cost was substantially less than a Razorblade, QRD 734, or comparable wood-constructed Omniffusor (though Omniffusor's fiberglass- reinforced gypsum option costs less).
Like Omniffusor, each panel provides hemispherical diffusion via 64 wells of varying depth in a "quasi-random" array that exhibits no obvious visual patterning. Coupled with lighter weight and slightly shallower depth (3'' vs. 4''), this anti-patterning is the most obvious difference between SpaceArray and Omniffusor. Both models offer a relatively flat diffusion coefficient from 125 Hz to 4 kHz, varying from roughly 0.8 at the lower end to 0.7 at the top, with a dip near 0.6 at the diffraction limit of 565 Hz. For smaller rooms like mine, these units perform much better in the nearfield than traditional Schroeder diffusors like Razorblade or QRD 734.
Naturally, SpaceArray's diffusive performance was my principal concern. I had nearly grown accustomed to sitting like a prized Pointer at a dog show in order to maintain the ideal listening position in my untreated room's sweet spot. In my Mac-based studio, I was unable to make RT60 measurements with the highly recommended ETF software (www.etfacoustic.com), and relied principally on my ears to judge SpaceArray's effectiveness. SpaceArray seemed to handle its job of tempering changes in mid and high frequency resonances around mix position. While mixing Danny Galaxy's retro-glam project Electric Love Angels, it wasn't as easy to slouch or shift to a spot where an overdriven Les Paul or vocal seemed exaggerated. Tonal qualities didn't shift as radically when simply reaching across the desk.
Those familiar with measuring room acoustics may be unsurprised to read that RTA frequency-response readings (with various tools) of the room at mix position, before and after installation of the diffusor panels, did not show appreciable differences in spectral quality; RT60 reverb time decay measurement would have been most telling. Pink noise tests measured with Metric Halo's Spectragraph showed a greater swing in frequency response between 600-800 Hz in the untreated room, with a 13 dB difference between min and max peaks. With treatment, the span tightened to 9 dB. In the domain of electric guitars from 1200-1800 Hz, the untreated room showed peaks 2-3 dB hotter than with diffusion.
SpaceArray panels can be easily dropped into T-bar grids for ceiling mounting. Through research and beta user feedback, SpaceArray's wall-mounting scheme has evolved. The current method provides an acoustical advantage over Omniffusor's flush mounting. Early SpaceArray shipments included scored aluminum pieces, which users folded into square cups. Four cups were inserted behind each panel, spacing SpaceArray 1/4'' from the wall. While playing test tones, I discovered a frequency which caused a nasty buzz between the cups and my wall, overshadowing the panel's diffusive benefits. Auralex responded with layered foam plugs. These were an improvement, but prone to failure if overtightened. Finally, Auralex introduced solid foam spacers resistant to delamination. In addition to being buzz-free, the new plugs lift SpaceArray an additional 2'' from the wall, helping improve SpaceArray's effect on the lower end of the mid-band. Moreover, with a spare set of plugs, SpaceArray is easily moved from one location to another.
SpaceArray's Paulownia wood construction has a nice, almond grain, lending a classy aesthetic vibe to the room. Having broken a price barrier for wood construction, SpaceArray represents a worthwhile diffusor option for those interested in a combination of form and function.
($399 MSRP each; www.auralex.com)
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