MIX'S 2001 GUIDE TO ACOUSTICAL MATERIALS

STUDIO DESIGNERS AND ENGINEERS MUST AGREE THAT, FOR BEST RESULTS, A RECORDING SPACE STANDS OR FALLS ON ITS ACOUSTICAL CHARACTERISTICS.

Studio designers and engineers may quibble over equipment choices, but all must agree that, for best results, a recording space stands or falls on its acoustical characteristics. And, in all but a very few cases, those signature characteristics need to be controlled or modified for each project. Most engineers use a gobo or two for separation during tracking sessions and, even in studios that boast some form of built-in variable acoustics, will occasionally need to create a temporary isolation booth. Similarly, control rooms and mixing suites will only provide an accurate monitoring environment when acoustic anomalies have been identified and corrected.

This article lists a wide array of foam, wall panel, baffle, barrier, ceiling tile and diffusion products to acoustically treat an audio space. The accompanying sidebar [page 46] describes a sampling of vocal booths and all-in-one audio enclosures for amps, computers and even human beings. Be sure to take note of specifications such as the NRC rating (Noise Reduction Coefficient) and STC rating (Sound Transmission Class) when shopping. The NRC tells you how much sound energy is absorbed (the higher the number, the more absorption), and the STC rates the amount of sound blocked in decibels (again, the higher the number, the greater the sound absorption). For example, a brick wall has an STC in the 50s, whereas a single-plate glass window’s rating may be 30. Another figure to be aware of is the product’s flame-retardancy rating.

Long the studio favorite and available in just about any form imaginable, foam products are cost-effective, easy to install, and are best suited for attenuating middle to high frequencies and for minimizing reverberation and reflections; foam is not generally very effective at just blocking sound.

Wall panels, which are more expensive than foam products, are usually constructed of fabric-covered frames filled with Fiberglas panels and can be covered in a wide range of fabrics. Baffles generally provide a combination of absorption and diffusion, and they can be quite flexible. Barriers are formed of layers of dense, limp mass that can make a wall, ceiling or door impervious to sound.

Ceiling tiles affect the largest area in most studios and are a cinch to drop into any tile grid. Fabric wall coverings can strike the perfect balance between audio logic and aesthetic beauty, and even the least expensive diffusion devices can work wonders to widen a sweet spot, increase clarity or reduce standing waves.

Whether your own acoustic challenge is finding stackable gobos and ready-made iso booths for a soundstage or soundproofing a converted single-car garage, you will probably find the solution in this list of acoustical materials manufacturers and their products.

Acoustic Sciences Corp.‘s patented Tube Trap, a corner-loaded bass trap, has been around for years. Most recently, the company has released three new studio configurations based on Tube Trap and Studio Trap, its freestanding acoustic gobo counterpart. The Quick Sound Field ($2,498) is a versatile arrangement of Studio Traps that offers three distinct recording environments at the turn of a few Traps. Rotating each Studio Trap’s reflectors outward creates a boom-free dead space; tightening or opening up the spaces between Studio Traps dials in low-level room ambience, and turning the reflectors inward toward the mic creates a bright, transparent sound. The AttackWall ($4,998) arranges Tube Traps, Studio Traps and ASC’s Monitor Stands to create a completely portable acoustic subspace for mixing.

ASC’s MixStation ($1,500) is a new acoustic mixing solution built for project studios and production suites. It comes complete with prefabricated, wall-mounted diffusive panels. Bastone Ceiling Panels ($98 per 2×2-foot panel) provide diffusion and bass trapping and drop right into any standard ceiling opening. The Iso-Wall Construction System (about $3.00 per square foot wall/ceiling area) uses ASC’s proprietary WallDamp, a visco-elastic polymer material, to absorb excess low-frequency energy and reduce wall shudders in high-volume music playback environments.

After marketing a line of soundproofing materials for many years, Systems Development Group recently called it quits. Several of that company’s more popular products are now carried on by Acoustical Interiors in the Sonora line (call for all pricing). Sonora Panels are high-density Fiberglas wall panels for sound absorption and are available in sizes up to 4×10 feet and from ⅛ inch to 2 inches deep. Sonora Panels come in one of 12 standard fabric coverings, and they feature square, beveled, mitered or rounded edges. Sonora Baffles are placed in or hang from the ceiling of a room. Made of a Fiberglas core housed in a spline-and-groove PVC frame (so that users can later change fabric coverings), Sonora Baffles are also available encased in a sewn fabric shell or encased in a black or white fire-retardant vinyl film cover. Sonora Ceiling tiles are made up of a barrier layer and a unique, soft, Fiberglas absorber assembled into an aluminum frame. Tiles are available for 2×2- and 2×4-foot grid systems in 9
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-inch widths, and they are covered in a wide range of fabrics.

The Acoustical Solutions (formerly Alpha Audio) Website includes applications and products for recording studios, as well as noise-control solutions for animal shelters, marching band practice rooms, gun ranges and houses of worship. AlphaSorb Wall Panels come in standard or custom sizes and with soft or resin-hardened edges, and they sport a sound-absorption rating of NRC .80 to 1.05 and a Class 1 fire rating. Prices range from $39 for a 1-inch-thick, 2×2-foot panel to $280 for a 4×4-foot, 2-inch one. The AlphaSorb Barrier Wall Panels (call for pricing) are combination wall panels that feature AlphaSorb Wall Panels and a strip of Audioseal Sound Barrier, a sound transmission blocker that has an STC rating of 27 and is dense enough to weigh 1 pound per square foot. Price is $472 for a 54×60-inch roll (270 square feet).

Acoustical Solutions’ Signature Sound Barrier Ceiling Tiles come in two sizes (2×2 feet and 2×4 feet) and replace standard lay-in ceiling tiles. Prices are from $15.50 to $88 per tile. The company’s Alpha Spiral ($72 for a 4-foot trap) and Corner Traps ($22 each for a 4-foot trap) are also available. The Alpha Spiral Trap is designed to fit over a tripod base microphone stand and absorb low frequencies. Each unit is easily raised or lowered on the stand to match a room’s needs.

Acoustics First Corporation offers a full line of sound solutions, including the Art Diffuser, Sound Cylinder, Composite Foam, Double Duty Diffuser and Cutting Wedge. The patented Art Diffuser ($79 for a painted, 15-inch square by 9½-inch-deep version) comes in a variety of 2-D, binary-array designs to offer one, four and five-octave diffusion. The Sound Cylinder ($160, two per box) is a freestanding, stand-mounted absorber with a rolling pattern surface that can be used in multiples to form a temporary vocal booth or mixing area. Composite Foam (from $25 to $55 per piece) can be used to reduce machinery noise and to quiet the noise leaking through open filler panels in equipment racks. Available with Tuftane or heat-reflecting Mylar surfaces, this line of foam/barrier combinations is also available with an aluminized Mylar facing. The Double Duty Diffuser Bass Trap (from $160 to $410) is available in a number of sizes, thicknesses, finishes and linings to scatter sound anywhere low-frequency absorption is a must, particularly across corners. Cutting Wedge acoustical foam ($208 for a 1×1-foot, 2-inch-thick sheet) provides the absorption of traditional polyurethane in standard 2, 3 and 4-inch thicknesses.

Sporting an information-rich Website for sleuthing sound problems, Auralex Acoustics offers a wide line of soundproofing materials and room-in-a-box solutions. StudioFoam Wedge panels (call for pricing) are 2×4-feet each; they come 12 to a box and are primarily intended for wall coverings and ceilings. The company’s T’Fusors are made from high-impact thermoplastic that drop easily into ceiling grids. T’Fusors are also wall-mountable — with pushpins, staples, Tubetak glue, nails, Velcro or 2-sided tape — and may be easily brush- or spray-painted. Twelve-inch Venus Bass Traps have an overall NRC rating of .30, absorb all frequencies and are particularly designed to soak up bothersome low-frequency waves. Auralex also makes MAX-Wall, the practical solution for studios and production suites using rented space and/or in need of a portable soundproofing solution. MAX-Wall is available in a variety of absorptive studio wall kits, complete with windows, cable openings and attached vocal mini-booths.

ClearSonic uses the latest in “see-through acoustic panel technology” to create panels that easily tame the loudest drum kit, guitar amp or trumpet section, while still maintaining essential eye contact. The aptly named ClearSonic Panel (call for pricing) can be folded accordion-like for easy transport and storage, yet it sets up with no gaps between panels where sound could escape. Perfect for surrounding a big drum kit, the ¼-inch-thick Panels are available in factory-assembled configurations that stand 24, 48 or 66 inches tall, and either 12 or 24 inches across. ClearSonic’s A2-4 ($120 with factory direct discount) is a new 2-foot-high ClearSonic Panel system designed for guitar speaker cabinets, allowing players to drive amps and speakers to preferred levels without causing leakage problems.

ClearSonic’s Flector Personal Monitor Discs (starting at $15) are 1
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-inch-thick, modified-acrylic devices designed to reflect sound back to a wind player or vocalist so that performers can hear themselves better during recording and rehearsal. The Flector discs also serve to diffuse the type of high-energy acoustical energy associated with brass instruments, which is especially helpful for other musicians recording nearby and directly in the “line of fire.” SORBER (call for pricing) is a new line of portable sound-absorbing systems that improves the performance of the company’s ClearSonic Panel by absorbing stray sounds that can cause drums to sound roomier than desired. Available in 4- and 5½-foot-high models (14 and 19 pounds each, respectively), both SORBER systems are 1½ inches thick, 4 feet wide and fold in half for easy mobility.

Those interested in checking out Folded Space Technologies’ baffle systems and sonic enclosures (see sidebar, page 46) can download samples from the Website of an acoustic duo’s CD recorded with the company’s products, a mini disc recorder and a pair of Shure SM57 mics. The Cloaking Device line of modular acoustic conditioning systems (starting at $144 for a two-piece travel kit system) are swivel stand-mounted baffle systems that can be used to improve overall room acoustics or to create controlled acoustic sub-spaces. Also available in ceiling- and wall-mounted versions, the Cloaking Device series includes Vox Box ($699), a nifty booth-on-the-go for recording vocals or instruments that uses eight Auralex-covered acoustic panels mounted on four 7-foot swivel stands. The Vox Box offers a controlled acoustic space with 64 square feet of absorbent and 64 feet of reflective surface area.

Many acoustical materials dealers sell Sonex-based products, and now all but Sonex One are available online directly from the manufacturer, Illbruck. Sonex One (call for pricing) is the company’s most popular product and is suitable for a wide range of uses and environments. Its sculpted surface of open-cell willtec foam is available in natural willtec and painted willtec, and is available in a Hypalon-coated version that can be wiped clean and is protected against dust and dirt. Sonex Classic ($213 for a 2-inch-thick, 24×28-inch roll covering 64 square feet) is a polyurethane foam version of Sonex One in a modified anechoic wedge design, and the Sonex Valueline ($169 for a 64 square foot, 1½-inch-thick roll) is a Class 1 fire-rated, absorptive foam available in painted charcoal, beige, brown, blue and light gray.

Known as a quality audio and video dealer, Markertek also markets an offering of affordable soundproofing materials under its own name. The MarkerTrap Low Frequency Sound Trap ($19.99) is a low-frequency sound absorption trap with unique diffuser blades. It mounts easily to walls and room corners for low-end control. Blade Tiles ($5.49 per tile) are 4-inch-thick absorptive polyester foam acoustic tiles that measure 16×16 inches and are available in charcoal or blue finishes.

MBI Products Company offers a range of acoustical control products for rooms ranging from voice booths to large arenas. Available in a variety of sizes and finishes, MBI’s Colorsonix Acoustical Wall Panels are suitable for most acoustical wall applications, and use a sound absorbent Fiberglas core that effectively eliminates reflected sounds while reducing sound intensity and reverb time.

In addition to recommending soundproofing products from 60 other companies, NetWell Noise Control offers a line of its own products. The company’s 3-inch Pyramids ($4 per square foot, available in 2×2-foot squares) are open-cell polyurethane acoustic foam panels with symmetrically identical, beveled faces to disguise seams between pieces mounted on a wall. The 4-inch-thick panel version has a .39dB frequency loss at 125 Hz and an NRC rating of 1.05; it is also available in standard 2- and 3-inch thicknesses and in six different colors. dB Bloc ($495 per roll) is a flexible barrier PVC vinyl material designed to keep sound from transmitting through the wall to which it is attached. Weighing in at a hefty 250 to 300 pounds per roll yet only 1
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-inch thick, dB Bloc is usually installed behind drywall and provides a 13dB transmission loss at 125 Hz and a STC rating of 26. NetWell also markets its Class-A-rated Fabric Panels at $7 per square foot in more than 48 colors. In addition, the company offers a thin, ribbed polyester material for light sound absorption called Silence Wall Covering ($2.30 per square foot) that is hung like wallpaper, and 2×2-foot melamine Ceiling Tiles ($5 per square foot) are available in a wide variety of bevel and painting options.

Distributed by CableTek, Primacoustic offers a variety of acoustical materials including diffusers, absorption panels and bass traps, as single items or entire studio room treatment systems. The Primacoustic line of broadband acoustical products are easy to install, affordable and offers the look and performance of an architectually designed studio. The system is based on a modular concept that combines different acoustical absorbers to resolve the four common problems in all square rooms: The Europa Flutter Wall controls front-to-back flutter and works with the Scandia Scatter Blocks to reduce standing waves; the Orientique Washboards reduce side wash and powerful primary reflections; and the Australis Bass Trap is a corner wedge that tightens bass and brings balance back into your room. More than a dozen standard studio room packages are offered, ranging from a $215 6×4-foot voice-over booth treatment to 12×16-foot studios in the $875 range. Prices even include glue, and panels are also sold individually allowing users to customize their designs.

Another great Website for learning about the fundamentals of acoustic soundproofing is offered by the folks at RPG Diffusor Systems. An extensive thumbnail gallery indexes a variety of architectural, home theater and project studio products, each with a close-up JPEG, extensive absorption and diffusion coefficient graphs and downloadable installation PDFs. RPG’s Skylines diffuser panel ($284 for box of two) is an art-worthy, 2-D “primitive root diffusor.” The Modex Corner ($564 for box of two) is a stackable corner-mounting, pressure zone membrane absorber that stands 25 inches high and extends 17 inches out from a corner along the mounting walls. The unit can also be used freestanding to deal with excess low frequencies.

RPG’s Studio-in-a-Box Silver Package (starting at $499 for Class-B and -C, $935 for white fleck Melaflex Class 1 material) is the company’s first in a series of affordable project studio packages. Included are 10 ProFoam wall panels for first reflection control, 32 ProFoam tiles for moderating diffusion and four ProCorners traps for extended low-frequency control. Available as demo downloads from RPG’s Website are Room Optimizer and Room Sizer, Windows 95/98 software packages that offer “automated listener” and “loudspeaker placement” advice, respectively. The programs are $99 each.

Silent Source offers its own line of WhisperWedge foam and AcousticCore panels (call for pricing). WhisperWedge is an absorptive urethane foam cut in 2, 3 and 4-inch thickness, the latter costing $300 to cover 64 square feet in a Class 1 melamine; a basic 2-inch foam covering more than 96 square feet costs $175. AcousticCore panels are available in a wide variety of core materials, depending on the panel’s intended application and are manufactured with semi-rigid Fiberglas. Any size up to 4×10-foot panels is available in resin-hardened square, radiused, beveled and eased profile edges, as well as in an aluminum-framed version.

The StackIt Gobo System from Taytrix is a portable, lightweight and very stackable gobo system. It’s ideal for miking and recording drums, vocals and guitar amps, and it can serve as a stylish way to isolate noise problems in non-recording environments. Walls stand 75 inches and are easily assembled, configured, transported and stored; panels are available in rose, slate, russet red, blue and forest green fabric coverings. Three styles include an absorption gobo for high- and midrange frequency help, a double-layered Plexiglas gobo for maintaining visual contact while sound separating drums and horns, and a combination gobo with features of both. Prices start at $306 for one gobo and run to $3,396 for a three-wall package.

Soundproofing panels from Vibrant Technologies include the DF-24 Diffuser Panel ($79 per panel) and Wave Forms Acoustic Panel ($99 covered, $69 uncovered). The DF-24, which can be dropped into any standard 2×2-foot ceiling grid, is a molded plastic panel designed to diffuse or disperse acoustic energy. Weighing just three pounds each, Wave Forms panels are molded over a lightweight thermoplastic panel and help provide damping of higher frequencies and diffusion of middle and lower frequencies. Multiple facets and angles redirect and redistribute sound waves to help eliminate hot spots and dead spots, while they maintain as live a sound as possible. Wave Forms are available in convex and concave versions in 48 colors of fabric; panels are also available without fabric covering for use as diffusers.

Wenger Corporation‘s lineup of diffuser squares and panels include the company’s Ceiling Diffusers (from $91 to $199), Quadratic Diffuser ($457), Trapezoidal Diffusers ($102 to $155 each) and Pyramidal Diffusers (from $58 to $150 each). The Ceiling Diffusers are made of impact-resistant PVC/acrylic plastic, Class-A fire rated and available in sizes from 2×2 feet to 4×4 feet. The 4×4-foot Quadratic Diffuser’s design is based on quadratic theory, and the Trapezoidal Diffuser is an offset trapezoid shape made of Fiberglas resin with a white gel-coat finish.

Randy Alberts is a musician, engineer and writer in Pacifica, Calif., who is not coincidentally sound-treating a turn-of-the-last-century artichoke farmhouse and turning it into a modern DAW-based project studio.

ACOUSTIC MATERIALS MANUFACTURERS

Acoustic Sciences Corp.

www.tubetrap.com

www.asc-soundproof.com

800/ASC-TUBE (272-8823), 541/343-9727

Acoustic Systems

www.acousticsystems.com

512/444-1961, 800/749-1460

Acoustical Interiors

www.acousticalinteriors.com

301/371-7979, 800/221-8975

Acoustical Solutions