Updated Room Measurements
Over the past year, since the previous measurements were taken, minor updates have been made to the room, and it has been re-measured to assess the impact of these changes on the overall room response. Since several changes were made at the same time before new measurements were taken, it is not immediately clear which changes did or didn't improve (or degrade) the audio measurements. (Of course, it may have been more efficient to make individual changes and verify the impact of each, but I was a bit lazy about returning to measuring the room.) In the end, this didn't matter because the physical room changes, at best, made subtle improvements.
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The changes to the room and audio equalization were as follows:
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Added roughly four 4-inch-thick panels. All panels consisted of 2 inches of fiberglass with a 2-inch air gap.
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Repositioned the front left and right speakers to move them slightly further from the front wall and removed their toe-in. They now point directly into the room, not at the listener.
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Although the same "main listening position" (MLP) was used for microphone placement, it is impossible to place the microphone in the exact same measurement locations; therefore, even a slight positional change will change the results.
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Instead of using the receiver's Audyssey application, the Audyssey MultEQ Android application was used on a tablet. This app offers additional customization options for the receiver's Audyssey equalization results.
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Last Updated: 10/04/2025
Measurements After Room and Software Updates
After making the above changes, the front three speakers were retested. Seven data points were taken for each of the front speakers. The microphone was repositioned as described in the Measurement Section of the Initial Measurements page. Then, for the SPL graphs, average these measurements together to determine if improvements were observed, and identify any consistent peaks or dips in the room's frequency response that could be corrected later. For RT60 and Spectrum graphs, typical individual measurement results were reviewed.
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A couple of differences between taking the recent measurements versus the previous ones were:
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For generating the RMS Average of all the measurements, 7 data points were taken (as compared to 5 previously),
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The microphone positions are not in precisely the same place, which can lead to some (hopefully) minor variations in results.
All measurements were taken using a full-range sweep, i.e., the frequency sweeps ranged from 15Hz to 20 kHz. Once the data was acquired, several graphs were generated and are reviewed below. These were RT60, Spectrum, and SPL charts.​
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Comparing RT60 Before and After Changes
Adding acoustic panels to the room could impact the reverberation duration, so it would be interesting to see if one can notice any impact (hopefully lowering) on the RT60 equivalent performance. RT60 can be generated for any one of the speaker measurements, and the results vary slightly between speaker measurements and microphone positions. A typical example of a before-and-after graph of RT60 is shown in Figure 1. The overall conclusion is that there is a slight (if any) noticeable improvement as a result of adding 3-4 panels.
As shown below, there is no difference in reverb times for frequencies above ~300Hz. Below 100Hz, the results varied significantly between measurement points, leading to the conclusion that there was no improvement in this area. The only slight improvement in measurement was observed between ~100Hz and 300Hz, possibly due to the addition of thicker panels. ​​​
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Given that the overall decay times above 200Hz are in the 200-250ms range, which is low enough that adding more panels would make the room sound too dead, but changing to thicker panels might slightly improve the upper base. Adding base traps could help the 20Hz to 80Hz frequency range, but finding room for them is problematic.
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Figure 1. RT60 Charts. Measurements before changes (left) and Recent Measurements Taken After Room Changes (right).
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Comparing Previous Spectrogram
The spectrogram tells a similar story as the RT60 graphs. Above 300Hz the decay times look the same between the previous and new measurements. ​Below 300Hz, it appears that there might be some very minor improvement in the overall heat-map, but it was not consistent between measurement points, so best conclusion one can draw from these measurements is that the decay times did not get worse.​​​
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Figure 2. Spectrogram Charts. Measurements Before Room Updates (left) and Recent Measurements After changes (right).
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Quick Look At Before/After Single SPL Data Point
As stated above, the typical methodology used when taking these measurements involved gathering multiple data points around the main listening position. However, it is also helpful to review some of the individual measurements to see if there are any anomalies on the individual curves that require further investigation. Figure 7 shows one such curve and includes some comments on the results.
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Figure 3. SPL graph for a single Measurement of the Front-Right Speaker.
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Comparing RMS Average SPL - Then and Now
Figures 8, 9, and 10 capture the previous and new frequency responses for the front three speakers. Each figure includes comments and observations on the corresponding graph.
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I had hoped that these graphs could help answer two questions:
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Did the room changes make any noticeable (i.e., audible) improvements?
Answer: Not really, a minor audible impact. The new SPL curves are smoother, but it's unclear whether this was due to the room or simply a better result from rerunning Audyssey. -
Did the Audyssey MultEQ app make any improvements?
Answer: Being able to adjust the target curve made an audible difference.
The difference in subwoofer level in the SPL charts is primarily due to a simple level adjustment in the AVR or MultEQ; therefore, the subwoofer level difference was not considered when reviewing the changes.
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As mentioned in point 1 above, some of the improvement in the results may be due to rerunning Audyssey, which can change the amount of correction applied and at which frequencies, resulting from slight changes in microphone positions. Therefore, some of the improvements seen in Figures 4-6 could be due to simply rerunning Audyssey.
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In two of the figures, there is some unevenness in the frequency response between 100 and 150Hz, which is around the crossover frequency for the subwoofer. This may be caused by an interaction between the front left/right speakers and the subwoofers. This issue can be addressed by adjusting the phase of the subwoofers relative to the main speakers. One way to do this is by changing the subwoofers' distance setting in Audyssey (either in the MultEQ app or in the AVR).
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Figure 4. RMS Average SPL Graphs for Front-Center Speaker.
Figure 5. RMS Average SPL Graphs for Front-Right Speaker.
Figure 6. RMS Average SPL Graphs for Front-Left Speaker.
Summary
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Overall, the minor changes in the acoustic panel configuration and adjustments to the front left and right speaker positions may have improved the measurements. Still, they appear to have made only a slight audible difference. The SPL results seem to be slightly improved. Using MultEQ and adjusting the target curve did make the intended subtle difference (or perhaps I think it did) in the overall frequency response.
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