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Reviewed by
Randall Smith


MondoTrap, MiniTrap
and RFZ Panel

Features SnapShot!


Model: MondoTrap
Price: $299.99 USD each
Dimensions: 57"H x 24"W x 4.25"D
Weight: 28 pounds

Model: MiniTrap
Price: $199.99 USD each
Dimensions: 48"H x 24"W x 3.25"D
Weight: 18 pounds

Model: RFZ Panel
Price: $249.99 USD each
Dimensions: 42"H x 32"W x 2"D
Weight: 15 pounds

Model: Stands (for MondoTraps)
Price: $79.99 USD each
Weight: 10 pounds

Description (cont'd)

System price: $2739.87 USD for 4 MondoTraps, 4 MiniTraps, 2 RFZ Panels, 3 Stands.


  • Real membrane bass traps for broadband absorption
  • Effective at low frequencies
  • Portable design
  • Nonflammable Class A fire rating
  • Mounting hardware included
  • All products in stock at all times
  • Various fabrics available

Over the last few years I’ve tried to make the most important upgrade possible to my audio system: a new listening room. I felt that every dollar I’d spent on my system had been well worth it, but at this point, what I was seeing and hearing from it were a bit overwhelming. I began to think that my sound system was just too big for my room, and that I could put up with the situation only until I found a new space to settle into.

But it seemed as if everyone in my part of the world had the same itch to move into something bigger and better. Real-estate prices went through the roof, and the bang-for-the-buck went down. My big audio system was forced to remain in my multi-use living room. I needed to adjust my attitude.

I broke my situation down into two categories: the visual mess and the audible disadvantages. The size of the components and their positions in my room couldn’t change unless I downgraded my gear, so there was nothing I was willing to do to improve how things looked. But when it came to the sound, I did have one viable option: room treatment. Besides, I’d always wanted to acoustically treat my room -- just not this room.

I began talking with friends about this, and quickly realized that treating the room would only add to the mess of how it looked. I decided that whatever sound treatments I chose had to be as aesthetically pleasing as possible. This meant that the quality of finish would be a big determining factor in any choice I made between buying room-treatment products and building them myself. Online research led me to RealTraps, whose website includes not only the measured results of their own products, but a wealth of information about room acoustics in general -- more than I found on the website of any other maker of room treatments. Nor did I think I could build sound treatments that would look as good or perform as well as what I could buy from RealTraps.

I e-mailed Ethan Winer, cofounder (with Doug Ferrara) of RealTraps, who requested a diagram of my room. I sent him a rough sketch showing my listening position, speaker locations, and the room’s dimensions. He also asked for some photos so that he could have a better idea of exactly where his products might fit into my room. A few hours later, Winer e-mailed me a proposal that he warned might seem a bit over the top, but would be the best possible starting place. He also said that he didn’t think there was such a thing as treating a room too much.

After giving Winer’s proposal some thought, the only change I made was to remove a single MiniTrap that would have covered a window 20’ behind my listening seat. What was left came to a total of $2739.87 USD, not including shipping: four MondoTraps ($299.99 each), four MiniTraps ($199.99 each), two RFZ Panels ($249.99 each), and three stands ($79.99 each). I placed the order.

A few days later, I pulled into my driveway and was greeted by the sight of nearly a dozen large cartons, which I lugged into the kitchen. The first box I opened contained a MondoTrap, which is designed to be placed in the corner of a room and to absorb low frequencies. The MondoTrap is 4’ 9"H by 2’W by 4.25"D, and made of rigid fiberglass wrapped in a thin plastic membrane and wheat-colored fabric. The plastic prevents the Mondo from absorbing high frequencies. The Mondo is housed in a sturdy metal frame that keeps the fabric taut, and also provides a way for the Trap to be attached to a wall or stand. The thickness and density of the fiberglass determine the degree of sound absorption; RealTraps claims that the MondoTrap absorbs more low frequencies that any other such product on the market, and they provide measurement data on their website to back it up.

Ethan Winer’s design required that I place four MondoTraps in three of my room’s corners: one each in the front and rear left corners, and, because of the room’s vaulted ceiling, two in the right front corner. To stack one MondoTrap atop another, I used two thin pieces of aluminum stock to screw the Mondos together, then mounted the bottom Mondo to a RealTrap stand. I then used transparent picture-hanging wire, also provided in the kit, to secure the top of the Trap to the corner. I placed the other two MondoTraps on stands in their designated corners.

The next box I opened revealed one of the four MiniTraps. The RealTraps website says that the Mini is their biggest seller, and perhaps their best performer. Each MiniTrap measures 24" by 48" by just over 3" thick. Made of the same rigid fiberglass as the Mondo, the Mini has similar qualities of low-frequency absorption, but is a bit smaller and slightly less thick. My Minis were to be mounted on the front wall in the corners, and on the rear wall near the ceiling.

Last were the two RFZ Panels (RFZ stands for Reflection Free Zone), designed to absorb the first reflections of the sound from the main speakers so that you hear more of the direct sound from the speakers themselves, not a mixture of that sound and its reflections off the wall. This improves the imaging and makes the sound more clear. Each RFZ, measuring 42"H by 32"W by 2" thick, was to be hung on wall like a painting. I had a friend slide a small mirror along the sidewall directly to the left of my listening position as I sat. When I saw the tweeter of my left front speaker reflected in the mirror, I got up and marked the mirror’s position on the sidewall, then hung the RFZ there, centered on that mark. I then repeated this procedure for the right sidewall.

With all RealTraps now in place, I recalibrated my system using the Automatic Room Optimization (ARO) feature of my JL Audio Fathom f112 subwoofers. This notch filter actively cuts the worst bass peak created by the sub’s interaction with the room. I connected the testing microphone to one of the Fathom f112s, placed the mike at the listening seat, and pressed the Calibrate button on the sub, which began a series of test tones that revealed and addressed the peak.


In the years I’ve been reviewing audio equipment, this was the first time I had ever heard a group of products make such an obvious difference in my system’s sound. Usually, during the ARO calibration, almost everything not glued down or screwed to the floor shakes and rattles. This can be a symptom of poor house construction, or some nasty room modes, or both. After installing the RealTraps, I was surprised to find that the many rattles caused by the low-frequency soundwaves flowing through my room were reduced to one here, one there. In fact, the ARO process, which can take as long as three minutes, was completed in half that time. Apparently, the MondoTraps and MiniTraps were absorbing enough low-frequency waves to make the process much simpler for the ARO software.

ARO completed, I grabbed my trusty RadioShack SPL meter and ran my speaker system through the calibration tones generated by my Anthem Statement D2 audio/video processor. In the D2’s Music setup menu, I set my Rockport Technologies Mira main loudspeakers to run full range, and my two Fathom f112s to overlap the Miras from 100Hz down, to help fill in any room modes.

The combination of the Mondos and Minis diminished many of my room’s frequency-response peaks, leaving a much cleaner, more natural sound. Notes that had been overemphasized were now far more agile and controlled. And with the bass bloat out of the way, my system’s speed and articulation were now on full display.

The mids and highs, too, were better, though not in such obvious ways. With the bass bloat gone, finer details at all frequencies were suddenly revealed. Vocal recordings now had a stability of imaging unlike anything I’d ever experienced in my room. The RFZ Panels absorbed those wicked early reflections and allowed me to hear my speakers to their full potential. As the RealTraps removed much of the room’s deleterious effects from the sound reproduced by the speakers, I suddenly had a new appreciation for the music, and for the quality of the audio system it had taken me so long to assemble. It was a kind of musical rebirth.

The first track of Neil Young’s Prairie Wind is "The Painter" [CD, Reprise 49580-2]. Before the RealTraps treatments, it had been difficult for me to differentiate the low-end instruments in the song’s opening notes -- what I heard was a loud, boomy note that could have been a kick drum or a bass guitar or both. With the RealTraps, the boom was suddenly gone, leaving the taut sound of a kick drum, followed by the sound of a brush hitting a snare skin. Also now far more prominent in this track were the sounds of Young’s pick strumming his guitar strings. I realized that, without the RealTraps, the sound had been one-dimensional, not a true reproduction of the actual recording. For an audiophile, using an excellent audio system to discover previously shrouded details in music recordings, and thus to be pulled deeper into the music, is one of the ultimate joys -- that’s what I experienced with the RealTraps in my room. It turns out that my system had been doing the trick all along; I’d just needed the RealTraps to brush away the cobwebs.

The RealTraps room treatments also greatly improved my experience of film sound. For many years, a favorite demo of mine has been the "23-19" scene from Monsters, Inc. The Pixar sound engineers, who always deliver the goods, put together an intricate mix: doors open and close, and conveyor belts run in the background, all accompanied by Randy Newman’s fun musical score. One moment that’s particularly fun to watch is when George Sanderson returns from a "scare." His partner, who had just been mentioning how much he loves old George, spots a human child’s sock on the hairy monster’s back. Although the monsters scare kids for a living, they’re actually deathly afraid of any contact with them. The sonic mayhem that ensues includes a hovering helicopter, windows slamming open, the sound of feet running around in panic -- a truly reference home-theater demo moment. To cap it off, the monsters’ security detail destroys the child’s sock with an explosive charge. The sound of this explosion is quite deep, and hits hard and quick. With the RealTraps in place, the sound popped into my room, then left as quickly as it had arrived, with no overhang. The Traps absorbed the sudden shock wave and helped prevent a dreaded rattle in the wall -- the one I can never find.

"Long Nights," one of my favorite songs from Eddie Vedder’s soundtrack for Into the Wild [CD, RCA 715944], provided a good illustration of how the entire RealTraps system worked together to stabilize a vocal image. Vedder’s voice is quite deep on this track, and in the past has excited my room, causing his voice to stand out more than it should. Behind Vedder, a bass guitar doubles the pitches he sings, a detail that my room’s bloating of Vedder’s voice had always obscured. Also, the image of the vocal should be stable, just to the left of center. Without the RealTraps, Vedder’s voice tended to increase in size and shift a bit. With the Traps, it was ultrastable and utterly clear, sounding more balanced and more transparent than ever before.


"What you hear is 50% the speaker and the other 50% is the room."

As I arranged to buy the RealTraps room treatments, I was excited to hear how much they might improve the sound of my system. I wasn’t prepared for just how much better it would get. I had long believed in acoustically treating a room, but had always held off because I intended to move to another house. What a lot of time I’ve wasted.

If you’ve invested hard-earned money in an audio system you love and you’ve begun to realize that your room may be masking your system’s full capabilities, I recommend RealTraps’ products. But first, visit their website and educate yourself in the science of room treatment. I believe that RealTraps’ products can give you more improvement for your buck than almost any other upgrade.

Review System
Speakers - Rockport Technologies Mira (mains), Energy Veritas 2.0Ri (surrounds), JL Audio Fathom f112 (subwoofers); Paradigm Studio 100 v.4 (mains), Paradigm Studio CC-690 v.4 (center), Paradigm Studio ADP-590 v.4 (surrounds), Seismic 12 (subwoofer)
A/V processor - Anthem Statement D2
Amplifiers - Anthem MCA 50, Krell KSA-50s, Coda Amplifier 11
Sources - Toshiba HD-XA2 HD DVD player, Sony PlayStation 3 Blu-ray player, Slim Devices/Logitech Squeezebox music server
Cables - Nordost, Monster Cable, DH Labs
Power conditioner - Shunyata Research Hydra Model-6 with Copperhead power cord
Display device - Mitsubishi WD-Y57
Remote - Universal Remote Control MX-850

Manufacturer contact information:

RealTraps, LLC
34 Cedar Vale Drive
New Milford, CT 06776
Phone: (866) 732-5872, (860) 210-1870

Website: www.realtraps.com

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