Background
It has been written that
“The room is the first thing we start with and the last thing we think about.” [1] How true is that for the vast majority of us? And yet it is all the more surprising given that each person reading these words counts sound quality of fundamental importance to them.
When considering treating one's room with absorption, two routes are available:
- DIY absorption.
- Commercially manufactured absorption.
A fellow Audioholics member took the DIY route, and in doing so provided me the invaluable opportunity to see, if not hear, the difference room treatment makes. By the project’s
culmination, I knew that I too wanted a piece of the action, but was unsure whether to opt for the DIY route, or the more costly but potentially more effective alternative route of commercially manufactured absorption. Ultimately, my decision came down to not wanting to take the DIY route, finding myself amazed by the results, and then thinking “I wish I had just spent that bit more and got even better results with commercially manufactured absorption”. I chose the latter route.
RealTraps
I am not usually one to buy just ‘good enough’. When it comes to things I am serious about, I always buy the best I can afford. Regular visitors to the
Room Acoustics, System Layout & Setup Forum at Audioholics will know Ethan Winer as someone who frequently yet selflessly gives demonstrably good advice to others. For this reason above any other, though after seeing some of the alternative products commercially available it’s little wonder, I decided that I’d buy either from
RealTraps, Ethan’s company, or not at all. Ultimately, I did buy, and went with four white (traps are available in black, white or wheat) 2’ x 2’ MiniTraps, six stands and the Mondo Room Kit (also in white), which itself is comprised of four 4’ x 2’ MondoTraps, four 4’ x 2’ MiniTraps and three 4’ x 2’ MicroTraps.
After picking up the traps from the airport (they can be delivered direct to the door for an additional surcharge) and getting them home, the fun began! First impressions were good; the traps came in robust cardboard boxes and were internally spaced from sides and corners to prevent damage in transit.
Stands came with the requisite number of screws and each was assembled quickly and easily with eight, the procedure being intuitive. The four MondoTraps and two of the MicroTraps (the third MicroTrap envisaged hung from the ceiling) were then attached to their respective stands by a further four screws each. Multiple holes in the stands allow vertical adjustment of panels by up to 18”.
Setup
There really is no getting away from having to experiment with trap/speaker placement and listening position to obtain the optimal room response. Thankfully, with regard to traps, this is somewhat simplified by the fact that straddling wall/wall, wall/ceiling and wall/floor corners is known to achieve the greatest absorption, though door and/or window placement in many peoples’ rooms may make this impractical.
Take my own room for example. It has three full-height glass windows along one wall, a double-width door opening along the opposite, bare walls and wood-laminate flooring. In addition, the room is square in plan. Acoustically speaking, it’s the second worst shape there is!
Then there’s the aesthetic factor; the traps maybe attractive in their own right, but my own feeling was still to maximise placement behind the listening position because I felt that a greater proportion of two-channel sound would be absorbed by traps in its first pass by me. It also ensured most of the front wall remained non-distracting to the eye and more importantly; free to project upon.
On the recommendation of others, I used Acoustisoft’s acoustic measurement program
ETF along with the (analogue) RadioShack SPL meter which sat atop a tripod placed at the listening position. This relatively easy to use program sends out a full-range frequency sweep, i.e. from 20Hz to 20kHz, over a five second period from, in my case, my front two towers (measuring was performed with the goal of achieving the best two-channel sound possible), and from the information received provides a comprehensive set of results.
After literally hundreds of measurements (which just might be related to my limited acoustic knowledge!), having incrementally moved the speakers back, forward, and sideways, toed-in and out, the couch drawn forwards and pushed backward, and every other speaker/couch/trap combination known to man, I finally settled for the following trap layout:
- The four MondoTraps placed in each of the room’s vertical corners (at 4” thick, MondoTraps are ¾” thicker than MiniTraps, hence absorb more and thus are best placed there).
- The four 2’ x 2’ MinTraps placed above the MondoTraps.
- One MicroTrap at the left tower’s side first-reflection position; the remaining two hung from both towers’ ceiling first-reflection positions.
- Two 2’ x 4’ MiniTraps additionally placed at the room’s rear corners, with the remaining two lain horizontally along the rear wall.
Note that the front-right tower’s side first-reflection position was left untreated because I felt that with the double-width door opening occupying this spot, thereby allowing sound at least partially to escape out of the room, the ceiling could better benefit by hanging two MicroTraps there instead of one.
Measurements
The following plots are presented in untreated/treated room order, though actually they were obtained reverse to this; after obtaining the best results I could, the room was re-measured unchanged except for the removal of the traps, thereby ensuring untreated/treated plots were compatible.
1.
Untreated/
treated room impulse response plot.
By treating the floor’s first-reflection position with a rug and the side and ceiling first-reflection positions with MicroTraps, the spikes at approximately 5 and 8ms on the untreated room plot are seen to have been tamed and the response improved generally on the treated room plot. In physical terms, treating the first reflection positions has increased the proportion of direct sound reaching the ears, thereby improving clarity and better defining the soundstage.
2. Untreated/treated room low-frequency room response
overlay.
3.
Untreated/
treated room low-frequency waterfall plot.
The overlay shows a significant reduction in the null at approximately 90Hz and smoothing of the response overall. This two-dimensional plot is effectively taken at time t=0; a snapshot if you will. By contrast, waterfall plots show how frequencies decay over time. Here, the traps may be seen to have helped in reducing the blade-like response to one much smoother.
Overall, more work is required in this region. I can’t help but feel that the relatively small size (4.2m square) and shape of my room make taming the low-frequency response more difficult than would perhaps be the case in a larger, non-square room. That said; by integrating my sub (crossed at 80Hz) with my towers, it should be possible to further improve upon the above frequency response due to the sub’s larger, more capable driver, and the far larger number of placement locations available to it.
4.
Untreated and
treated room full-range frequency response.
Here you can see the reduction in comb filtering the traps have made. Comb filtering results from the combining of direct sound and reflected sound, so reducing this will again cause an increase in clarity and soundstage definition to be realised.
Conclusions
So what about the all important questions; how does the music actually sound? And were the traps worth it?
Let me begin by saying that to date, I have owned three distinct separates hi-fi systems. For me, its sheer delight hearing at each upgrade ever greater detail from songs I thought I knew like the back of my hand, all the while knowing that the CD is still the same; I’m simply hearing more of what was always there.
All things considered, I believed my room sounded pretty good untreated. But I can honestly say that that was as nothing compared to the utterly captivating sound and unprecedented level of detail I now enjoy.
From Brenda Russell’s elegant
Piano in the dark to
The might of Rome from Gladiator, which never fails to raise the hair on the back of my neck. From The Lighthouse Family’s rich
End of the day skipping along to Mark Knopfler’s crackling finish to
Speedway at Nazareth from Sailing to Philadelphia, bass is wonderfully tight, cymbals are biting sharp and the front soundstage is incredibly well defined. For the first time in my life, I have made significant inroads at being able to hear the quality of sound radiating from my speakers, and let there be no doubt; it’s very, very good.
To me, RealTraps were worth every penny. I cannot recommend them highly enough.
Robert T Buckle
RealTraps review
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Linear Mode
