First Steps - Designing an Auralex Treated Room
After all the years of my restriction to living space as my primary theater room, I was excited to be finally building a dedicated room in my new home for this single purpose. Unfortunately I was unable to make it the classic rectangle that home theater aficionados and acousticians hope for when designing the "ideal" home theater room.
Realizing my new theater room had some issues, mostly in symmetry and low end modal control, I elected to call on the pros from Auralex to see what kind of solution they could offer to my dilemma. It was refreshing for me to hear them not scold me on my room shape but instead offer a voice of encouragement on my project. A particular memorable thing that Jeff Hedback said to me was " it is basically predictable to acoustically treat a rectangular room. But it takes much more ingenuity, science and art, to balance and neutralize a non-rectangular room, the kind more commonly found in people's living spaces".
With that, I faxed them a crude sketch of my room layout as illustrated below (left). After weeks of deliberation and defining to Auralex what my goals were for the room, they proposed a treatment plan illustrated in the below right figure.
Room Design Goals
Before we settled on the treatment plan illustrated above, I precisely defined my design goals for this room as listed below:
- Very open and natural sound conducive for high caliber music listening and movie watching
- Superb control of low end response without sacrificing amplifier power or dynamic range
- Uniform sound for all listening positions
- Aesthetically pleasing theater like look and feel
My biggest concern (which I was repeatedly vocal about) was that I didn't want to create a typical sonically "dead" room so many audiophiles love. I wanted this room to sound very natural and open, while at the same time be focused and uniform for a wide listening area. A lofty goal perhaps, but NOT one in which Aur alex felt they couldn't tackle.
The key to getting a theater room right is to understand the goals the end user has, including listening preferences, equipment dynamics, aesthetic and budgetary considerations. Being mindful of all of this, I conducted an interview with Aur alex to understand their thought process behind my room and to ensure I concisely conveyed my intentions and expectations for how this room should turn out.
Interview with Auralex
Interviews with: Brian Wheat , Jeff Hedback and Jeff D. Szymanski , PE
Audioholics: Please provide a background of Aur alex (history, target business, place in market, etc)
Headquartered in Indianapolis , Indiana , Auralex Acoustics was founded in 1977 with a mission to provide the best acoustical treatment products at the best value. Our products enjoy widespread use among many prominent artists, producers, engineers and corporations and can be found in recording and broadcast studios, home theaters, houses of worship and other commercial applications. For more information, about us, feel free to visit our website at www.auralexelite.com .
Audioholics: What type of room analysis did you do on the Audioholics room prior to designing an acoustical treatment solution?
The program used is called CARA ( www.rhintek.com ). Unlike many "calculator" type programs that can be found free on the 'net, CARA offers the ability to model complex rooms, like your "L" shaped room. In your case, we toyed with loudspeaker placement quite a bit and ultimately determined that, regardless of placement, there were some specific modal issues that were going to cause a problem. The space has a primary modal profile from the longest Length and Width dimensions and "subsets" of modal distributions from the "L" shaped nature. The various subsets will affect the "sonics" of the space differently: the Length, Width, and Height of the rear seating area is the most important modal subset.
Audioholics: Please explain the various products you selected in the Audioholics showcase room and detail their functions.
The key to designing and ultimately selecting the right products for the space relies on the following question; " how do I create a balanced response at multiple seating positions with great clarity and definition between spoken word, sound effects and musical content?" For your room, we incorporated the following products:
Auralex CFS- Custom Fabric System - An installed treatment system that places acoustically designed treatments (absorption and diffusion) behind aesthetically elegant acoustically transparent fabric. The thickness of the treatment follows the acoustic design needs of the space.
Aur alex Mineral Fiber Insulation - cavity resonance control and bass trapping benefits for your seating riser(s).
SpaceArray Diffusors - provides hemispherical acoustical diffusion based on a quasi-random series.
SpaceTrap - Prototype bass traps designed by Russ Berger.
DST-R Flat Reflector - 1" EPS diffusive panel to provide a diffusive soundfield in areas where space is limited such as side and back walls
Sonofiber Absorption - high density, (.75) NRC rated for 1", Class A flame retardant absorption treatment used to treat first reflection points and bring symmetry back into the room.
The front wall is treated with 2" CFS absorption from floor to chair rail height providing good broadband absorption control of rear energy off your speakers. Portions of the left sidewall have 2"CFS absorption, other areas that were to be exposed drywall have CFS EPS flat board and other areas in the rear have DST-R diffusive panels. The rear wall has sections of DST-R diffusive panels and flatboard and best results are relying on the proposed theater curtain over the rear window.
The rear right sidewall has a SpaceArray on the door and DST-R diffusive panels on the actual wall surface surround. As the room works around the AirHockey table, the treatments are essentially a 50/50 blend of 1" CFS absorption and DST-R diffusive panels. The goal is to minimize coloration due to the asymmetrical profile without over treating the space, a fine balance that should prove to be right on target once the space is fully completed.
The ceiling has 18 SpaceArrays above the seating positions and a CFS 1" absorptive pod between the seats and main speakers. The SpaceArrays will offer a greatly enhanced response between the seating positions and are specifically intended to enhance your surrounds' function. They will also yield the more cinema "feel" of a higher ceiling. The 1"CFS pod is needed to minimize comb filtering of ceiling reflections with the direct sound from your LCR speakers. Again, this is a fine balancing act between control and the need to retain a natural response in the space. The detriments on untreated first reflections would be far worse than small potential gains of a more "normal" room feel. In simple words, this treatment combined with your carpet may yield the subjective feel of a very treated room…I await the final results, but this is needed.
Your Status Acoustics Titus speakers are going to excite the room beyond typical modal concerns, thus extreme bass trapping is needed regarding of how the modes overlap. To address this, we are placing three of the prototype Auralex PartScience bass traps in the space which are designed by Russ Berger. We will turn the riser for your theater seats into much needed additional trapping. We also have multiple broadband absorbing CFS columns that will clean up issues between 150- 400 Hz.
Audioholics: Please describe the basic functions of diffusion, absorption and bass trapping.
Diffusion - evenly disperses sound energy rather than remove the energy. Results can be an increased sense of room volume which can enhance the performance designs of bi/di polar surround speakers. Diffusion panels can be used in a design combination with absorption panels to control parallel surfaces and yield a more natural response.
Absorption - absorbs sound energy. The performance of an absorber is qualified by its NRC value…simply the higher the number, the more effective the product is. You would look at products with a .8 NRC rating for general control and products with 1.0 NRC or higher for more critical applications.
Bass Trapping - control below 100 Hz, can be attacked in many effective ways. Typically vertical corners and wall/ceiling junctures are treated. There are other pressure points that can be treated for low frequency control.
Audioholics: What are the most challenging aspects of the Audioholics showcase room?
Lack of acoustical symmetry combined with the performance specs of your speakers (see Status Acoustics Titus First Look).
Audioholics: Is there anything you would have done differently in the room if aesthetics weren't a factor?
From our perspective of reviewing the original design and now physically being in the space…we don't expect the need for changes. The original acoustical design placed Auralex SpaceCouplers over the 1" absorption pod on the ceiling. We are curious how the use of the SpaceCouplers might have projected energy toward the seating area. Visually, the SpaceCouplers would conflict with the projector so they were taken from the end result.
Building a Home Theater Riser
The next step before the theater chairs from Continental Seating arrived, was to build a Riser platform to raise the back row seating for better viewing, increase tactile response, and to help serve as a broadband absorber at low frequencies for better bass control. Auralex again came to my aid with the blueprints for this platform to serve all of my needs while also form fitting into my rooms dimensions and decor.
In our next installment, we will look at 3-D modeling of this space to take a virtual tour of the Audioholics Showcase room followed by actual photo's of the completed job as comparison. Before and after measurements of the room will be included to illustrate the benefits of a properly treated room. We will also show step by step instructions on how to construct a theater chair riser which will serve as a bass trap and natural resonator to increase tactile response. Most importantly, we will do critical listening tests to determine if we have reached audio nirvana, or need to make additional tweaks to make the room worthy of the name Audioholics.
For more information about Auralex, visit: www.auralexelite.com