Room Acoustic Analysis and Acoustic Treatment for an Audiophile Listening Room

by Nyal Mellor August 24, 2016

Client Profile

Mr. Maciag is an audiophile from Florida whose purchase of an XTZ Room Analyzer II Pro stimulated his interest in room acoustics and the pursuit of a room free from acoustical problems.

 

Project Overview

The audiophile listening room which Mr. Maciag had allocated was a challenging space to work with, having openings on both side walls and a peaked ceiling.

The high end audio system installed included Magico S7 speakers, a D'Agostino Momentum integrated amplifier and PS Audio Directstream DAC.

 

Acoustic Frontiers Solutions

We conducted our "standard" Room Acoustic Analysis / Acoustic Treatment Design service. The main issues identified from the analysis were:

• Room mode resonances at ~40, ~60 and ~120Hz
• Left / right speaker loudness imbalances in key areas of the frequency spectrum including 200-400Hz
• Excessive mid / high frequency decay times

One particular challenge for us with this room / system was the inability to use our favored multi-subwoofer / room correction strategy to deal with frequency response anomalies in the sub-100Hz region. There was also no real way to change speaker / listener positioning enough to work around the major resonance at 40Hz. This left the heavy lifting down to acoustic treatment. Select items of the treatment plan included:

• RPG Modex Plate Type 2, to deal with the resonances at 40 and 60Hz
• RPG BAD panels at front and rear wall reflection points, to reduce speaker boundary interference cancellation
• RPG BAD and Omnifussor panels on the ceiling to control reflections and reduce overall decay times

The Results

The room turned out very well visually, with the use of painted Omnifussors and BAD panels color matched to the walls and ceiling.

Acoustically, the post-install measurements were much better, but the 40Hz resonance lingered on more than optimal.

Our initial root cause analysis for the 40Hz resonance focused on the 1st axial length mode, hence the front wall placement for the two Type 2 Modex Plates. After installing all the panels, we instructed the client to re-measure the room, by sweeping it with a 40Hz sine wave and locating the area of highest SPLs. It turns out that there was a secondary resonance related to the dimension between the front wall and the corner next to the listening position. Movement of a single Type 2 from the front wall to this corner resulted in a 4dB reduction in the strength of the 40Hz resonance!

After discussing the result with the client, it was determined that an additional two Modex Plate Type 2s would be added in this corner. Unfortunately the existing design is too high for two to be stacked in this corner, but a "v2" is in development with different dimensions that will allow a dual stack. The "problem" corner with the built in bookshelf at the back right side of the room. Future plans are a dual-stack of the v2 RPG Modex Plate Type 2s to further reduce the severity of the 40Hz resonance[/caption]

In the Client's Words

"From the first moment we listened to the system it was obvious the treatment made a major improvement: the echos and reflections were gone and full range response was smoother. Although I had previously invested thousands in very expensive components, and hundreds of hours in system adjustments and tweaks, it was only after we added the RPG room treatments to Nyal's specification that the room began to sound "real". It is amazing how important comprehensive room treatment is, relative to the usually considered priorities of speakers, source, amplifiers, etc. Perhaps room treatments aren't as sexy as the latest new component but they perform the essential task of removing room colorations that can't be done in any other way." Mr. Maciag.

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