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Location:
Orange County, California
System Installation:
Mark Ontiveros
Acoustic Engineering by:
Anthony Grimani
Photography:
Glenn Campbell
Audiophile Meets Videophile

You’ve seen some pretty elaborate theaters on the virtual pages of Revolution Home Theater, from an Irish pub-themed home theater to a retailer’s demo room that looks like the inside of an Egyptian tomb. Spending tens, if not hundreds of thousands, of dollars turning your living room or basement into a vintage ‘20s theater or something straight out of “Star Trek” may sound exciting for those lucky few of you who have more money than you know what to do with. But the frugal AV enthusiast who thinks that performance is the most important factor in home theater design should pay particular attention to this month’s featured theater.

You won’t find ye olde candy shoppe, popcorn machine or red velvet curtains as you enter the dedicated theater and music listening room of this beautiful South Orange County home. Installed by Mark Ontiveros and his team at Audio Images in Tustin, CA, the vibe one gets when entering this subdued grey theater is reminiscent of a small screening room at a movie studio. Stylish wall sconces provide light and black leather chairs dominate the center of the room, but there are no fancy-schmancy design touches such as flowers, artwork, crown moldings or cleverly disguised equipment storage areas to hide the gear. The room is all about watching movies and listening to music.

Acoustic designer Anthony Grimani of PMI, Ltd was brought in to ensure that the room had a smooth frequency and time response and could be easily tuned, even through future gear changes. Getting the room dialed in for one pair of speakers does not mean it’s going to work equally well for future multi-channel speaker layouts. PMI’s acoustic work focused on several areas. First, the room length/width/height was dimensioned for optimized bass standing wave resonance performance. The worst room dimension belongs to a cube shape. Since the resonance frequencies are identical in all three axes, PMI worked with the available real estate to find the rectangular room ratio for best distribution of those pesky resonances. Second, PMI developed a sound isolation scheme for the room, so that the homeowner can enjoy his music and movies at full tilt without being heard in the family room above. A resilient wall construction scheme was developed to provide sound isolation and control the bass resonance remaining after the shape optimization. The ceiling was suspended from a spring system, the walls were mounted on rubber isolation bushings and the floor was floated on rubber isolation pads. The resilient wall structure actually absorbs low-frequency energy through compression and expansion of the suspension system, instead of returning low frequency wave fronts into the room where they would otherwise decay slowly in the resonance frequencies. So the resilient construction serves to improve sound isolation, as well as to reduce standing waves. You get tight punchy bass and domestic harmony, all for a few thousand dollars of materials.

Third, PMI designed an HVAC layout for reduced noise in the room, and for reduced sound transfer to other rooms in the residence. The noise floor of the listening room will dictate the ultimate audible dynamic range of the program material and must be kept as low as possible. Threshold of hearing (0dB SPL) would be ideal, but up to 15dB SPL is acceptable for audiophile performance. Anything above that will step on low-level details and will invariably force you to turn up the volume, thereby hurting your ears, and possibly damaging your speakers. Fourth, PMI worked on the speaker layout for best stereo separation, reduced boundary reflection errors, and best sound field integration throughout the channels. Fifth, PMI determined the optimized reflection decay time for the room, and computed the right amount of absorption and diffusion treatments to achieve this target decay time. Recent research in the field of “psycho-acoustics” has shown that most music listeners like approximately the same decay time in a given room volume, and the results are published in ITU recommendation documents. PMI followed those guidelines, and the homeowner concurred that the program material sounds absolutely fantastic in his new room. Once the calculations were completed, PMI scientifically laid out the absorption and diffusion treatment materials throughout the walls and ceiling to control the sound reflection patterns and polarize them for optimal imaging and articulation. Components of the CinePanel® acoustical treatment system were utilized in the implementation, along with added custom-cut fabric-wrapped diffusion panels. Sixth, PMI designed custom bass “trap” absorbers to round out the bottom frequencies of the room. The bass absorbers are large “Helmholtz” boxes with perforated front surfaces, which all resonate in the predicted bass response error regions. The seventh and final step was to figure out the optimized seating locations for best interface with the room bass response for the speaker layout established for the room. PMI documented all of the above recommendations in a full color plan set that Robert McCarthy Builders (General Contractor) and Audio Images carefully followed throughout the construction process.





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