Subwoofer Placement Combined with Signal Processing – Part III

The data of the condition of the room are listed below:

  • Almost square shaped
  • One opening to another space
  • One side wall mostly out of glass
  • Sloping ceiling
  • Front and rear walls with large alcoves
  • Listening positions are distributed over a wide area
Figure 1: Example of Room mode attenuation by combining subwoofer arrangements with signal processing.

Check different situations!

situation A

By looking at the raw data in (a), one can see that there are large seat-to-seat variations in the listening area expressed by the Mean Spatial Variance (MSV) of 23.62.

The variation in the relative levels (dB) at around 52 Hz for two different seating positions is significant. Approximately 22 dB that is about four times louder in the perceived loudness and about 160 times more power for the subwoofer to bring in to make up for this difference

situation B

In (b), it is obvious that the sea-to-seat variations could have been addressed, however, the low-frequency performance is still not smooth which is due the two subwoofers in failing to attenuate the front-back wall room modes.

As could have been shown before, the performance of 4 subwoofers in the right positions can deal with most of the resonances in a certain frequency range.

situation C

In addition, for the four subwoofer arrangement in (c), the sound field management found a need to reduce the output from one of the four subwoofers by 6 dB and two by 12 dB. Equalization filters are applied to each subwoofer and two of them are delayed by 5 and 10 ms respectively.

The advantages of two different active sound optimization approaches combined can be clearly observed in the final frequency response.

In this post, we explained first part of Subwoofer Placement Combined with Signal Processing; Other types of these methods that need to be mentioned to improve the sound will be published in future posts. These will pave the way for creating a home theater of the highest quality.

Although, we explored two types of sound absorbers that are effective in controlling sound reflections; Other types of these absorbers and the things that need to be mentioned to improve the sound will be published in future posts. These will pave the way for creating a home theater of the highest quality.

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