Clean Up Your Room! Part 2: Acoustic Treatments
By MARTY CUTLER
Wed, 25 Jul 2012
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by Marty Cutler

LAST MONTH, WE REVIEWED DIGITAL TOOLS THAT DETECT ACOUSTIC PROBLEMS in your studio and compensate for them to help you do better mixes. They generate test tones, listen with a measurement mic, analyze the results, and make EQ-based corrections at the output stage of your recording system. As effective as this approach is, it can’t correct what your room may be doing to your sound at the input stage—mainly to anything you record with a mic. So while that synth bass you bounced to disk sounds fat with plenty of attack, the electric bass you re-amped may sound thin and papery, and vocals may sound smeared and ringy.

Testing Methods
In small, parallel-walled rooms, bass frequencies can accumulate in corners and become boomy, or cancel each other out and become quieter or even inaudible. Higher frequencies bounce off the walls and can cause fl utter echoes, ruining the imaging of sounds in that range. With that in mind, we tested acoustic treatments from three companies, made listening observations, and analyzed the results through IK Multimedia ARC—it takes highfrequency issues into account as well as more common low-end problems, and while not a reference spectrum analyzer professional studio designers would use, it is a tool real-world musicians are more likely to have. I sent each company a mockup of my room, with dimensions, doors, windows, and anything else that might alter the path of sound waves issuing from my monitors. Th e companies then sent me room treatments they deemed appropriate.

Fair warning: You’ll need to be handy with a drill and anchors to get some (but not all) of these products up. Because mounting panels can be a trial-and-error process, it would be great if more manufacturers provided alternate mounting materials suited to temporary placement. I’m not keen on poking multiple holes in the old drywall of my old house, especially in something so ephemeral as a spare bedroom studio. Given my skill level, I decided to use industrial-grade Velcro wherever possible.

Primacoustic
primacoustic.com

If your room suffers from a particular acoustic foible, Primacoustic has a solution for it, ranging from isolation tools to bass traps, gobos, diff users, and much more. You can pick and choose treatments on a piece-by-piece basis; the website is immensely helpful at explaining room issues. You can also select kits designed for different sized rooms from project studios to nightclubs to home theater.

My room falls under the category of project studio, and with that in mind, Primacoustic sent me their London Kit 12, which comprised a pair of 24" x 48" x 2" Broadband Panels, eight 12" x 48" x 2" Control Columns, and a dozen 12" x 12" x 1" Scatter Blocks. The panels were primarily dense fiberglass with an aesthetically pleasing, grey, textured fabric.

Mounting hardware was a box of drywall impalers, screws, anchors, and even the proper size drill bit. I was expecting standard bass traps, but according to Primacoustic, the larger Broadband and Control pieces cover a very wide range of frequencies. Bear in mind that kits are generally starting points, and Primacoustic offers a variety of hardware a la carte for fine-tuning.

Fig. 1. A desktop view of a pair of Primacoustic Control Columns flanking either side of a single Broadband panel.
My attic door, situated at the left front corner of my space, precluded putting a bass trap there. Instead, I initially mounted the larger Broadband panels at the front of my room, directly parallel to my rear wall: the left unit temporarily over my window, and the right one on the wall directly in front of me, with a couple of Control Columns at the right and left of the right-hand Broadband panel. (See Figure 1). Th at left mostly smaller spaces, where I could mount a few more columns and fi ll in the gaps with the smaller Scatter Blocks.

Now to listen. As much as I loved my untreated room sound, I was immediately and unequivocally aware of a fabulous improvement in clarity. Th e imaging, which my Tannoy Reveal monitors always provided in spades, was even more spacious and accurate. I work by myself most of the time, but I collaborate frequently enough that I appreciated the broader sweet spot, although the bass was more emphatic, bordering on boomy, in the left rear corner of the room. Th at made sense, as it was the corner with the least available treatment. Finally, I worked a mixdown using the same sequence material I used for last month’s story. Due to the balance and clarity the treatment provided, it was significantly easier and quicker to get results that were pretty darned consistent across a variety of playback mediums, including my home system, an iPod with earbuds, and my car stereo.

The ears say one thing, and inevitably, measurement software says another, so I loaded up ARC and swept the room. Interestingly, the right channel profiles were remarkably similar with a lot of mild mid-to-high-frequency bumps, albeit with a bit of an increase in amplitude in the right channel in the treated room. Below 200Hz, the readouts were similar before and after, again, with slightly increased amplitude peaks at roughly the same frequencies, including a pronounced dip in the left channel at about 100Hz in the treated room. I’m guessing I would’ve seen more improvement here had I put proper bass traps in both forward corners.

I tried mixing through ARC in conjunction with the room treatment. Oddly enough, I preferred my new Primacoustic environment without it, as the audio took on a bit of a brittle high end with it. In fairness, ARC offers alternate frequency rolloff curves, which could likely smooth this out.

RealTraps
realtraps.com

If your workspace is as compact as mine, the fact that your space changes dynamically is a given. Add one 19" rack, and furniture may move. RealTraps recognize that and offers modular systems on stands that you can move as your space changes. Primacoustic does this as well, but mainly for their portable gobos such as the Freeport series.

IK Multimedia ARC measured room
response before and after installing
acoustic treatments. Get screenshots
of the results and room diagrams at
keyboardmag.com/july2012.
I received four MiniTraps, designed to catch bass in corners; three MicroTraps, whose one-inch thickness is focused on mid-to-high frequencies; a couple of stands, and the requisite mounting hardware.

Mounting is deceptively simple. Once I fully grasped the setup procedures, it took me only minutes to attach and use the MicroTraps, which I’d mounted on stands. The assembly instructions would be better with step-by-step diagrams for the mechanically challenged such as myself.

Because these units are free-standing, I had no issues with the doors in the left-hand corners; I could put traps there while working, then slide them away for door access (see Figure 2). A MicroTrap on a stand to my left stood in front of the closet door and another in the left front window tamed reflections from the glass. Th e third Micro perched in a groove in my righthand window for similar reasons, with the added benefit of dampening outside traffic noise.

The MiniTraps in the corners did a great job of cleaning up the bottom end, and making it consistent over a fairly wide area. Imaging was excellent, but for some reason, upper frequencies and transients seemed present enough, but without the “sparkle” of the Primacoustic kit. Likewise, the sampled acoustic bass seemed to lose much of its high-end snap.

After moving things around a bit, I defaulted to relying on just a heavy curtain in my righthand window, and moved that trap to a stand on the right, and parallel to the microtrap on the left. Now, imaging and clarity were great—the “front” of each instrument, including the bass, was clearly defined. In more exposed moments on the track, the beautiful Ron Carter-style growling vibrato on the instrument shone through. Th e sparkle present in the Primacoustic set was replaced by well-defined but velvety highs. Ultimately, this smooth high end would sit well with long mixing and tracking sessions, in which overly present treble can be fatiguing.

Fig. 2. RealTraps’ modular design
makes it a snap to reconfi gure
your studio. A MiniTrap in my front
window absorbs nasty wall-to-glass
refl ections. A MicroTrap sits in each
corner to break up bass frequencies.
The measurements from ARC didn’t necessarily support my perception, however; if anything, dips and bumps in the amplitude of frequencies over 200Hz were slightly less dramatic, but only faintly so. In any event, I was satisfied with the resulting transferability of the mix across playback systems.

Pairing RealTraps and ARC was somewhat more listenable than with the Primacoustic treatments, but I heard no significant difference between using both and using RealTraps alone. Apart from a noticeably lower amplitude overall, which was probably just the position of the ARC plug-in’s trim knob, I couldn’t hear any perceivable change in timbre or image.

Auralex
auralex.com

As with the other manufacturers, I sent them a mockup of my room, but I also fi lled out their room analysis survey at their website. Here, you outline the purpose of your room, the typical music you record, the dimensions, and so on. You also profile your room’s acoustic symptoms and submit a diagram. Auralex then develops a custom treatment strategy based on your needs, budget, and visual aesthetic. I received a dozen two-foot square, one-inchthick Sonolite panels, which are made of fabricwrapped acoustic foam and mount on walls or ceilings to tame reverb, ringing, and fl utter echo; a pair of ProMax portable broadband absorbers— large foam panels on stands (they serve as bass traps in my setup, but you can deploy them as isolation for tracking vocals and acoustic instruments); and a box of four bamboo Peak Pyramid diff usors.

Auralex had sent me detailed placement instructions for everything (download the PDF at keyboardmag.com/july2012). Putting everything together was simplicity itself. In a couple of instances, however, placing the Sonolites required a few detours from their plot, which had no detrimental eff ect on the overall treatment plan. Mounting the Sonolites was a breeze, thanks to the double-sided adhesive pads provided; I even removed and repositioned them once or twice when my measurements were a little off with no damage to the walls (see Figure 3).

The ProMax Absorbers were easy to assemble. Each absorber is halved and dovetailed together around a cylindrical insertion space for mounting on the provided mic stand. This provides some flexibility in adjusting the height of the foam business end of the absorber.

Fig. 3. Auralex Sonolite pads on the walls surround a ProMax Absorber on a
stand. My monitors sit on Auralex MoPADs, which decouple them from the
desk and preserve low end.
I arrayed the Peak Pyramid Diff usors above my head, slightly in front of the overhead fan with each pyramid pointing 90 degrees away from its neighboring piece; according to Auralex, this helps disrupt overhead reverb and harsh reflections without completely deadening the space. The Pyramids were too heavy to mount with adhesive; the job called for drywall anchors for my ceiling. I’m not terribly handy with a drill, so I pressed my wife into service. (She can set up a mean patch bay, too.) Handily, Auralex provides the mounting anchors and screws.

When the dust and drywall cleared, I was rewarded with a remarkably clear and consistent sweet spot with burnished highs, a distinct midrange, and clear bass. During denser moments, you could really make out the growling vibrato on the acoustic bass, and more importantly, its distinctive envelope, rather than the tonal thud I used to hear when things got busy. I could even hear the release samples during more exposed passages. A gorgeous pedal-steel-type pad from Spectrasonics Omnisphere retained its character amidst mandolin tremolos, acoustic guitars, a swirling phased Rhodes, and a sawtooth pad. In my untreated room, that would’ve been a recipe for the steel to get lost in the sauce. It was easy for me to carve out space in the mix for each instrument. Walking from left to right in front of my desk, the sweet spot was not nearly as broad as the Primacoustic treatment, but broad enough to invite a collaborator or two.

ARC results explained much of what I heard in the high end above 2kHz, whose divergences from the ideal fl at response were minor—and very consistent over both channels. Mixing with ARC active proved to be a decent pairing in this instance. I enjoyed a bit of a wider sweet spot marked by more consistency in the bass. Clicking on ARC’s Full Range Bass Correction added a bit more bottom without smearing the notes.

Conclusions
The Primacoustic London Kit is a class act. Attractive as well as eff ective, it can easily blend into a home studio without looking out of place. Most importantly, it provided a balanced frequency response throughout an impressive amount of area around my central listening post. Realtraps off ers robust and reasonably priced solutions for the home studio. I can’t emphasize enough how crucial it is to be able to adapt your room conditioning to the minute developments that can aff ect small spaces that are pressed into service as recording studios. Auralex provides a comprehensive set of aff ordable tools for room treatment. Once again, the modular design is a tremendous boon to small project studios where you’re often moving things around.

No room treatment product is an end-all solution. A glance online at each manufacturer will reveal an incredible variety of treatments for every nook and cranny in your room, but don’t go to the point of anechoic overkill—no musician likes a completely dead room.

The concept of a room with a perfectly flat response is a myth. What should matter are your ears. In each case, I was able to get a better aural picture of each sound’s stereo placement, timbre, and loudness in my mixes than I had when I had started. I mixed, tweaked, and adjusted with a solid idea of what my tracks really sounded like— resulting in a more consistent listening experience when I was done.

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