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Andy Hong
Gear Geek and Gear Reviews Editor
Tape Op Magazine
Last updated August 2005
A glass-block window and two skylights facing south provide lots of natural light. An open ceiling tricks you into thinking that the tracking room is much bigger than it really is, especially when it's viewed through the control room glass. In reality, it's about the size of a living room. |
Acoustic treatments for the small recording studioLast year, I wrote an article about the merits of recording drums at home. In the time span since that article was published, I've been hard at work building and tweaking a small, project-based recording studio that would exhibit some of the positive traits of a home studio—a facility with lots of natural light, easily-modifiable acoustics, and bigger-studio sound despite its living-room-like dimensions. My colleagues and I chose to build the rooms with bare walls, with the goal of acquiring, building, and experimenting with various acoustic treatments—off-the-shelf and DIY—to afford us easily modifiable sonics, both in the control room and in the main tracking room. The walls themselves were built using standard studio construction methods, so they'll remain more or less unmentioned here. Instead, the focus will be on the treatments being tacked onto the walls or placed inside the rooms. As we continue to add or change the acoustic treatments in the studio, I plan to make available on this page some of my reviews pertaining to studio acoustics that are being published in the print version of Tape Op magazine. In addition, you'll see here additional notes, measurements, and observations that didn't make it into the print reviews. Product reviews on this page: Primacoustic Primakit acoustical treatment Primacoustic Freeport acoustic panel Acoustical Solutions, Inc. Acoustical Solutions, Inc. RealTraps MiniTraps & MondoTraps
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Single Speed Design My brother and I are partners in an architecture firm. Naturally, we hired ourselves to design the studio spaces. Single Speed Design employee Erik Carlson (of the band Purple Ivy Shadows) did much of the design work and completed the construction drawings. Cavanaugh Tocci Associates provided acoustic consulting. DiNoia Construction was the general contractor. |
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An early shot of the control room before installation of the Primacoustic Primakit. Four of the twelve RealTraps are visible. In the middle of the photo, two RealTraps are installed in the corner. The glass window to the main tracking room is on the right. Six RealTraps are visible looking at the front of the control room in this shot, taken after the Primakit was installed. Six more RealTraps are installed at the back of the room. Because bass energy builds up in corners, it's important to mount the traps as close to the corners as possible for maximum benefit. Frequency response of the control room at mix position with and without bass traps installed. With the bass traps, there's a general smoothing of the bass and lower midrange. Also, a significant reduction in bass "ringing" between 90-120 Hz tightened up the low end. (Click to enlarge.) Unfortunately, even with the bass traps installed, a big hole exists at 63-72 Hz. Why? The main axial dimension of the control room is 18 ft, measured between the front and back walls, which are the only parallel surfaces. A 63 Hz soundwave has a wavelength of 18 ft. A 72 Hz soundwave has a wavelength of 15.7 ft, the distance between the monitors and the back wall. The mix position, which is approximately a quarter wavelength away from the monitors for the attenuated frequencies, is in one of the null points of this second-order resonance, where reflected soundwaves cancel direct soundwaves. Check out the RealTraps MiniTraps & MondoTraps review below for an update on the low-end frequency response. The additional traps really helped to even out the lows. And the addition of a subwoofer, carefully placed to least excite the room modes, not only took care of the hole at 63 Hz but helped the low end significantly throughout the whole room. |
RealTraps bass trapsWhy are bass absorbers a necessity? Bass reflected off walls leads to standing waves. Standing waves create huge peaks and dips throughout the low end. Without bass absorption on the walls, some spots within the room will have too much energy in certain frequencies and too little in others. These peaks and dips in the low-end response will change as you move around the room. Adding foam or fiberglass to your walls to reduce reflections can compound problems in the low end, because these products tend to work only above bass frequencies. But up until recently, adding bass traps to a project studio was too expensive, took up too much space, and/or required significant amounts of DIY construction. Recently, bass-trap guru Ethan Winer and friend Doug Ferrara started RealTraps the company to manufacturer and sell affordable, ready-to-install bass traps. Their first products are membrane absorbers that hang on the wall. The SB, LB, and HB models utilize a thin, plywood panel that resonates when low frequency soundwaves hit it. Behind the panel is an airtight space with rigid fiberglass that dampens the panel's resonance. This highly-damped resonance is what absorbs the low-frequency waves and prevents them from reflecting back into the room. The new, fiberglass-paneled MiniTraps work the same way, but at an even more affordable cost-to-benefit ratio. I recently outfitted my studio's control room with twelve RealTraps LB7 and HB7 wood panel traps. Installation in my control room involved attaching mounting bars (included with the traps) on the wall with toggle bolts and drywall screws (depending on location of traps vs. location of the studs) before simply hanging the traps onto the mounting bars. (I faxed Ethan the plan for my control room, and over the phone, he helped me choose the number of traps and the location of each trap to maximize absorption.) Post installation, I immediately noticed "tightening" of the bass response. I heard "more" bass and less mud. With their angled fronts coming off the wall by about six inches, the RealTraps also provided a good deal of diffusion, reducing some of that small-room "phasing" caused by reflections interacting with the primary sound sources. My ADAM S3-A monitors, already punchy and clear in the low end, sounded even clearer. Curious to see how the benefits measured, I pulled out my trusty Terrasonde Audio Toolbox and performed RTA and RT60 tests, with and without the bass traps installed. (Another advantage of RealTraps? You can remove them easily and take them to your next studio!) Summary: smoothing of response between 30 and 50 Hz; 3 to 5 dB reduction between 63 to 250 Hz, an area where there was too much bass buildup at mix position (at 100 Hz, there had been a peak that was 8 dB higher than the average SPL); some smoothing from 1.3 kHz on up (diffusion at work); and a measurable reduction in reverb time. What does this mean? It's now much easier to make decisions about the low end than it was before, and tracks heard in my control room translate better when heard elsewhere because my room imparts less of its acoustic signature to what I hear in the room. If you have a project studio, especially one that's been treated with foam, fiberglass, or rug (yikes!), I urge you to consider adding bass traps to your studio. For the price of a few good mics, you could outfit your studio with RealTraps panel absorbers, and the benefit to the sound of your recordings would be far greater than what you'd gain from spending the same money on gear! MiniTrap: $199.99 direct; SB, LB, and HB Traps: $479-$599; www.realtraps.com
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Ethan Winer is a name you may recognize He's been a published author of audio-related articles since the 70s, and he's a regular contributor to many of the online forums. In 1995, he wrote an article for Electronic Musician that detailed how to build an affordable, low-volume bass trap that actually worked. The latest revision of the informative article is still available on Ethan's personal website, and I'd bet it gets a gajillion views per month, given that it ranks #1 in Google for the search phrase "bass trap." |
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Looking over the console desk. The foam "form" on the right is made up of 16 modular pieces glued onto the wall. On the left behind the chain are 15 modular pieces glued onto and next to an exposed brick column. The foam "form" to the far right of the console is made up of six modular pieces. The woods panels in the corner and to the right of the foam are RealTraps bass traps. A close-up of one of the foam forms. Frequency response at mix position with and without the Primakit. Notice the significant smoothing in the midrange due to the reduction of comb-filtering caused by first reflections. (Click to enlarge.) Also, one of the goals of the Primakit installation was to bring the midrange reverb time down to 0.5 s to reduce blur without making the room too dead. RT60 reverb time measurements (A weighting): 810 ms before installation of Primakit; 465 ms after installation. Goal met! |
Primacoustic Primakit acoustical treatmentMy control room, built into an old engine factory, has some odd shapes and features that make it fairly non-rectangular. Therefore, when we designed the room, we knew that if we used an off-the-shelf acoustic treatment, it would have to be extremely customizable. Primacoustic makes a series of highly-modular, ready-to-install Primakits that make specification and installation incredibly easy, whether you have a normal room or a non-standard space like I do. Five different types of foam modules are included. The installation manual and product brochure (both well-written and informative publications come in the kit), recommend numerous installation patterns and include a good explanation of expected benefits. Engineer and audio-hacker Rachel Uwa and I followed the instructions and had the 13 ft x 18 ft control room treated in four hours. In addition to the foam modules, our London Studio 16 kit came with more foam-safe Liquid Nails adhesive than we needed. Installation onto drywall and brick couldn't have been easier. And sure enough, the different module styles—assembled into "walls"—made for a professional look, despite the "challenging" architecture. After installation, we ran the same FFT and RT60 tests we'd done pre-Primakit. More importantly, we listened with our own ears and heard an obvious difference. Mud gone. Imaging cleaned up. And as Rachel described the control room sound before we installed the Primakit: "I even had to search to find my low end because the high end was so harsh and distracting." After installation: "Now, the highs are crisp, the midrange is well defined, and the low end is right where it should be." The previous week, I'd recorded drum tracks using a minimal mic setup. With lots of mics on the drums, I oftentimes have to fight the crunchy harshness of the hi-hat bleeding into all the mics-a result of "phasey" comb-filtering. In the pre-Primakit control room, the hi-hat sounded harsh, despite the minimal mic'ing. Post-Primakit, that harshness in the hi-hat completely disappeared. Turns out the phasey-ness that I had heard was a result of uncontrolled reflections in my control room, now subdued by the Primakit. What about competing products? There are two characteristics of Primacoustic foam that make it stand out as the best of the breed. One I've already mentioned: extreme modularity. The other: unlike other foam treatments, the Primacoustic foam has far less "marketing shape" to it. Anechoic wedges and pyramids made of foam are far less effective than broad sheets or angles (of the same outer dimensions)—with open-cell foam, more material equates to more absorption, and with Primacoustic foam, you get twice as much material. Also, Primacoustic claims that their foam is the densest and therefore the most absorptive. What about rigid fiberglass? Fiberglass has better acoustical properties for a given thickness (and is ASTM fire-rated for industrial applications), but I couldn't find a system utilizing fiberglass that's as modular and easy to install as a Primakit. So when it came to choosing an acoustic treatment for my control room, it was an easy decision: Primacoustic Primakit was the clear winner. $450-$750 MSRP; www.primacoustic.com
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Comments from audio-hacker Rachel Uwa I can very easily say that I knew little about control room acoustics upon my arrival in Boston. Most of the recording environments that I've been in have been completely professional, designed by folks who know what picante sauce is supposed to taste like!! Suffice it to say I hadn't questioned my listening environment too much. Certainly, when you walk into a new studio you bring in your reference CD but that just gives you an idea of how things translate; you don't generally then say, "Can we add some acoustic treatments to these walls so that I can get my 400 Hz to sit right?" So I get to Andy's place, and he's got these boxes of foam that we're supposed to hang up around the monitors and the console, and I admit I was a little skeptical. How could putting up random pieces of foam on your walls improve your sound that much? Well I got to do some listening tests before and after, and I found that the foam really did work out great!! Before the foam was in place I noticed that a lot of the songs I was listening to sounded muddy and because the highs were sitting on top of mud, the overall picture just didn't sound quite right. I even had to search to find my low end because the high end was so harsh and distracting. I was surprised too because the monitors were ADAM S3-As, which I love. My brain automatically started to question the quality of the recordings; if the monitors are great and the room is decent, what else can the problem be? I was so happy when after all the work and testing was done, I was able to go back and give the room a second listen. And I was even happier when I realized that the mud was completely gone!! Now, the highs are crisp, the midrange is well defined, and the low end is right where it should be. Plus the room looks great!! A note about foam and fire safety No doubt you've heard about the deadly fire in a Rhode Island club that was fueled by burning polyurethane foam. Unlike the untreated foam that was hanging on the walls of that club, Primacoustic foam is embedded with fire retardant and has passed the California C117 test. See Primacoustic's informative page on fire safety for details. For our own test, Rachel and I took a piece of Primacoustic foam and tried to ignite it with a blowtorch. Although the foam melted slowly and gave off a nasty stink, it would not burn. As soon as we removed the flame, the foam stopped melting and the fumes dissipated. (Our pyrotechnic feats were performed outdoors, and we held our breath.) |
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As seen through the control room glass, two Freeports on either side of Nedelle help reduce the room ambience making its way to the mic during quietly sung moments, resulting in a more "intimate" sound without complete "deadness." |
Primacoustic Freeport acoustic panelIn my "live" tracking room, I've tried hard to spec out treatments that are easy to mount, unmount, move, and swap, with the goal of an acoustic signature that I change easily. I had a contractor who specializes in building movie sets fabricate a whole bunch of custom gobos, boxes, and hanging dividers for me. They were beautifully made, and they function well. At the same time, I acquired a pair of Freeport freestanding panels. When I give visitors or potential clients a first-time tour of my facilities, they never ask about my custom-made acoustic "furniture," but they always seem to be interested in my Freeports. They usually walk up to them, talk into them at close proximity, crane their head around to look at the back of them, then poke the front of them. I'll admit that I did the same thing the first time I saw a Freeport at a trade show. Why is the Freeport so interesting? It's just a few sections of high-density foam glued to a 2 ft x 4 ft corrugated-plastic sheet mounted on a stand made up of PVC pipe. Sounds simple, doesn't it? Well, it is simple. But it's executed so well that it looks very cool, and it does a great job of providing "tactical" acoustic treatment. I find my two Freeports most useful when I'm tracking vocals. They have just the right amount of absorption to tailor the sound of the "room" that makes its way into the vocal mic. Just by varying the placement of the panels around the mic and vocalist, I can make the room sound bigger/smaller, darker/brighter, or harder/softer. At 6 ft tall, the panels will work with most vocalists. You can of course place milk crates (or equivalent) beneath them to temporarily raise them higher. Or you can buy longer sections of PVC pipe (readily available at any hardware store) to make them taller. The Freeports are also useful when tracking acoustic guitar, especially if the guitarist is sitting on a stool—again if you need to vary the sound of the room and if you also want to reduce the amount of vocals reflecting back into the guitar mics. A surprise usage scenario? Room mics for drums. Position so that the plastic side faces the drum kit, and the foam side faces away. Place a mic on the foam side. You'll get less cymbal wash and more "oomph" from the drums. Other uses? Behind your speakers to reduce first reflections coming off the back wall. In front of windows that you don't want to cover permanently. Field recording when you don't have the luxury of a controlled recording environment. And speaking of using these for field recording, the Freeports are extremely easy to assemble, disassemble, and transport—no tools or instructions required. And if you're a one-man studio operation like I am, you'll appreciate the Freeport's light weight (9 lbs), especially when you're moving the Freeports through small doorways or through the maze of drums, amps, cables, and mic stands that your live room becomes during a tracking session. Also worth noting is the fact that the acoustic foam used for Freeports is impregnated with fire retardant. Now I kinda wish that I'd had fewer custom-made acoustic panels made and instead invested in a second pair of Freeports. The Freeports not only perform well, but they're so quick to set up. Having a pair of Freeports is like having a variable "intimacy" control for your room that's incredibly easy to tweak. $300 MSRP pair; www.primacoustic.com
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Thom Moore of The Moore Brothers and Nedelle sing inside the Versipanel "vocal booth" that was created by unwrapping a Versipanel wall into a semicircle. A Primacoustic Freeport is positioned on the left, between the mic and the control room glass. The semicircular "booth" from the other side. |
Versipanel Wrap-Around WallI usually track "basics" with all the players, instruments, and amps in the same room. I find that musicians perform better this way. Unfortunately, the situation can get pretty "washy" with all the sounds bouncing around inside a single room, and the bleed between instruments can sometimes be a liability. Recall my statement earlier about designing my live room so it utilizes moveable acoustic treatments for variable acoustics. Now imagine the excitement I felt when I discovered a wall that I can roll out when needed, vary in shape to divide up my live room into efficient acoustic zones, and roll up for storage when no longer required. The Versipanel roll-out wall is a flexible, free-standing divider made of life-preserver foam and covered in fabric. Vertical ridges allow the wall to curve, making it easy to form semi-enclosed spaces within a room or to follow the contours of existing walls or furniture in a room. Versipanels are made to order, and can be a maximum of 8 ft tall and 35 ft long. Compared to other foam products, the Verispanel has excellent absorptive properties, most likely due to the extreme density of its foam. And it's incredibly durable, more so than any other acoustic product I've seen. During a recent two weeks of tracking, I had the opportunity to use two Versipanels to control the acoustics in my live room. While tracking basics, I rolled out a 6-ft tall wall behind the drum kit to tame the reflections coming off the rear wall. I rolled out a 4-ft tall wall in front of the kit to reduce the amount of direct bleed between the drums, amps, and non-corresponding mics. The two Veripanels effectively created a "drum room" within the live room with significant attenuation of first reflections and bleed, allowing me to place my main drum mics a few feet from the kit. I left the sloped ceiling and the upper parts of the two-story tall walls uncovered, so there would still be a good deal of splashy room reverb making its way into the room mics. Of course, the effect on the drum sound was far less pronounced than what would have been accomplished if the drum kit had been in its own tracking room altogether, but that kind of extreme isolation was not what I was looking for. When it came time to do overdubs, the Versipanels were handy for "focusing" the sound of the guitar amp. By varying the "wrap" of the wall around the guitar amp, it was easy to adjust the "tightness" of the amp's sound to suit the character of the guitar part. While recording backing vocals, the Versipanel walls were used to define areas of the room that were dry and areas that were reverby. And I'm now looking forward to utilizing the roll-out walls for an upcoming session with a string section. $12.50 per sq ft MSRP; www.versipanel.com
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Acoustic measurements and fire safety Up until it was recently revamped, the manufacturer's website had a table of acoustic ratings and a summary of flammability characteristics for Versipanel walls. This data is no longer available on the manufacturer's website, but Silent Source, a distributor of Versipanel, has that data and more on its website. |
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AlphaSorb Clouds mounted above the recording console and mix position. Each panel is angled so that first reflections from the ceiling and from the panels themselves are minimized at the mix position. The panels were hung from a structural beam with steel angles, c-clamps, and 20 gauge wire. |
Acoustical Solutions, Inc.
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Acoustic measurements, sizes, and fabric choices AlphaSorb panels can be ordered in custom sizes and covered with custom fabric to fit your studio's specific needs. I specified "stock" sizes and colors for my control room, but even these were made to order. I'm sure turnaround time varies for each order; mine arrived within a couple weeks after I faxed in my contract. See the manufacturer's website for sizing and fabric options. You can also download the technical data sheet (pdf) for a chart of sound absorption coefficients. |
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AlphaEnviro Hanging Baffles mounted on the walls of the live room, as seen from the live room's balcony. Each baffle is 8 ft tall and hangs from a pine strip that's mounted approximately 11 ft above the floor. The wider baffles are 4 ft across and the thinner ones are 2 ft in width. The same baffles as seen from the floor. The washy reflection on one of the baffles on the right is from the camera's flash. Another corner treated with AlphaEnviro Hanging Baffles. (Excuse the junk next to the piano... I was setting up for a recording session.) |
Acoustical Solutions, Inc.
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Covering choices, sizes, and acoustic measurements Ordering options? Covering: PVC, PVF, or ripstop nylon. Size: height and width. Thickness: 1'' or 2''. Grommet placement: any combination of edge and corner locations. See manufacturer's website for details. You can also download the technical data sheet (pdf) for a chart of sound absorption coefficients. |
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This is a close-up shot of a drum riser floating on PlatFoam. Two layers of 3/4'' plywood are glued together and screwed down to 2x4 runners. PlatFoam strips are placed 6'' center-to-center. Only the PlatFoam strips touch the floor. (There's a 1/4'' gap between the 2x4 runners and the floor.) A cheap rug sits on top of the plywood. |
Auralex PlatFoamIn Tape Op #34, I wrote about my studio's lack of floating floors, and how the Auralex GRAMMA isolation platform reduced the amount of bass-amp rumble escaping the main room. I also noted that the GRAMMA had an immediate and very discernable effect on the "tightness" of the sound coming from the bass amp. The GRAMMA utilizes two pieces of high-density PlatFoam to decouple what you place on it from the floor. This same PlatFoam can be purchased by itself in box quantities to float larger structures. 24 pieces of 4 ft long 2'' x 4'' strips come in a box of PlatFoam, along with three tubes of TubeTak adhesive, enough to support an 8 ft x 8 ft area. Loving the positive effects of the GRAMMA in my studio, I decided to build a 6 ft x 8 ft drum platform for my live room using a box of PlatFoam, 3/4'' subfloor plywood, 2'' x 4'' runners, drywall screws, and a tightly woven rug. (Runners or sleepers aren't normally required—I used the runners to solidify the grooved joint between the subfloor pieces that make up my 6 ft deep platform. My runners don't touch the floor, only the PlatFoam does.) Design goals? Quick build, stable, passable through doorway... and of course, less drum sound making its way out of the studio. Once I'd collected the materials, it took me four hours to build the drum platform by myself. First my comments in regards to construction. The PlatFoam strips vary in thickness by up to 2 mm. Even with the strips glued six inches apart center-to-center, that variance is enough to make a platform constructed of a single layer of plywood bouncy/flexy. I'd recommend using two layers of plywood glued and screwed together to prevent flex. TubeTak will hold foam onto wood tenaciously, but its immediate stickiness gives you a false impression that the adhesive has already set. The foam will pull away if you try to position your platform before full curing has actually completed. Wait at least 24 hours. Auralex recommends using an electric carving knife to cut their foam. I obtained good results using a hot-wire foam cutter. My comments in regards to acoustic benefits? I'll make this short. The difference is much bigger than I anticipated. Especially for the "khoof" of the kick drum and the "pwack" of the snare drum—I hear less of them outside of the tracking room. And unexpectedly, I hear much less bleed of the drums in the guitar and bass amp mics. Apparently, a good deal of the drum bleed was being transmitted through solids: across the floor, through the mic stands, and into the mics. The PlatFoam-floated drum platform reduced this thru-solid transmission significantly. Less bleed, more focus, better drum sounds. Design goals accomplished... and then some. $199 MSRP box; www.auralex.com
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Other methods of floating Instead of PlatFoam, you could try neoprene or other rubber-based materials. Heck, you could even buy a bunch of foam in bulk and cut it yourself into strips. Personally, I think PlatFoam is the easiest (and least time-consuming) way to go about it. If you want to try other materials, make sure you've got enough damping in the material to prevent the platform from resonating too much. Also, make sure that any resonating that you do encounter is at an inaudible (infrasonic) frequency. |
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SheetBlock was used to soundproof two skylights. SheetBlok was cut into panels, and then two layers of panels were sandwiched between three plywood frames (imagine a club sandwich). Each SheetBlok layer had one hole cut into it. The two holes are in opposite corners; air (and sound) that enters one hole must follow a labyrinthian path between the panels to exit out the other hole. This reduces sound leakage while preventing condensation and pressure buildup. |
Auralex Acoustics SheetBlok
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Construction products Most audio geeks equate Auralex with foam products. The company also sells a number of professional materials for studio construction, including hard to find items like mineral fiber and resilient channel, as well as SheetBlok. See Auralex's construction products webpage for details. |
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MiniTraps mounted at the front wall's ceiling-to-wall juncture. MondoTraps mounted at the rear wall, above the couch. MiniTraps are above. Whoa, check it out. A huge improvement in the low end after installing the MiniTraps and MondoTraps. The hole that existed between 63-72 Hz is much smaller, and there's significantly more energy below 63 Hz. (Click to enlarge.) |
RealTraps MiniTraps & MondoTrapsIn Tape Op #36, I reviewed the panel traps that RealTraps used to manufacture out of wood. In issue #38, Larry Crane reviewed RealTraps MiniTraps, which performed so well (while being easy to ship) that the company stopped making the wood panel traps. Since then, RealTraps partners Ethan Winer and Doug Ferrara have added MondoTraps and MicroTraps to their line. The MondoTraps are similar in construction to MiniTraps in that they're made of panels of rigid acoustic insulation bonded to a limp-mass membrane, wrapped in cloth, and framed in metal. (This design increases low-frequency absorption by more than half over plain rigid fiberglass of the same density and thickness.) You may recall in my review of the original wooden traps that even after installation of the bass traps, I still had a fairly big "hole" in the frequency response of my control room between 63-72 Hz due to the axial dimension of the room. I wanted to "fill in" that hole a bit and also reduce the rear wall reflections for band members sitting on the couch in the back of the room. Therefore, over the course of a few months, I ordered and installed six MiniTraps and three MondoTraps for my control room, and more for my live room. My first test was to place a single MondoTrap in the floor-to-wall corner at the front of the control room, hidden on the far side of the recording console. Using my trusty Terrasonde ATB 1, I generated tones at 1 Hz intervals and measured the response before and after placement of the MondoTrap. I was surprised at how effective that single trap was at filling in my low-end hole. Between 44-89 Hz, the bass response went up an average of 3 dB. After the rest of the traps were mounted (some on the rear wall and wall-to-ceiling corners, and some on the front) another set of measurements showed an increase in bass response of 5-7 dB throughout most of that same range. Furthermore, my secondary goal, reducing the rear-wall reflections for the couch-bound band members, was achieved. Imaging and bass response on the couch were discernibly improved. I can't say enough about how awesome RealTraps products are. I'm convinced that they're the most cost-effective, off-the-shelf means of treating a small room for low-end acoustics. When people ask me what gear they should buy to improve the sound of their home or project studio recordings, I tell them to buy RealTraps bass traps, because a room with crappy acoustics will give you crappy recordings, no matter what mic or compressor you use. Check out the RealTraps website for all sorts of new additions to the company's product line, including gobos, stands, and even built-in SoffitTraps. Volume discounts and room kits are also explained on the website. $299.99 direct for a single MondoTrap; www.realtraps.com
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Help with studio acoustics Ethan Winer, the man who popularized the DIY bass trap, and co-founder of RealTraps (along with his partner Doug Ferrara), moderates the MusicPlayer Studio Acoustics Forum. Check it out for both expert and peer-to-peer advice on studio acoustics. |
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Careful placement of a subwoofer makes sure that the 63 Hz resonance is no longer being excited by the speaker system. Not only is the hole gone at mix position, but that room mode is no longer as strong. Therefore, while walking around in the room, 63 Hz and its adjacent frequencies no longer change drastically in amplitude. (Click to enlarge.) |
Addendum: Adding a subwooferThe problem with relying on nearfield monitors to reproduce the extreme low-end is that the optimal position for the nearfields in terms of imaging and detail (everything but the low-end) may not be the best place for the bass to be generated. The low-end response of the room is most likely to be affected by standing waves as a result of the size, shape, and materials of the room. Standing waves are what cause the peaks and dips in the low-end response. By separating the low-end driver—the subwoofer—from the main left & right monitors, you can move the low-end driver to a position in the room that least excites the room modes (without sitting in a null point) and therefore causes the fewest standing waves. I installed a Bag End InfraSUB-12 PRO subwoofer in the front of the room (firing toward the rear) so that its baffle is 5.5 ft from the front wall and its center is about 1 ft away from the side wall. Although my console and other furniture limited the placement of the subwoofer, I did have enough leeway so that I could adjust for fewer standing waves. Now the low-end response throughout the whole room is much more even, and the extreme dips and peaks, especially the one at 63 Hz, are pretty much gone.
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Calculating room modes There are a number of free room mode calculators on the web, including one from Mr. Bass Trap himself, Ethan Winer. Ethan's ModeCalc (download) runs on Windows and DOS. On the Mc Squared website is a JavaScript Room Mode Calculator that runs in your browser. Dr. Dan Russell has a very educational webpage with animations discussing the effect of source location on room modes. His website has many other discussions on other acoustics topics as well. |
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Photos by Rachel Uwa, John Hong, and Andy Hong. |
Last modified: 06 July 2023 |