I am trying to optimize the sound in my family room.
With my large subwoofer in the only WAF-friendly location, I found a large cancellation at around 40Hz in my listening position. I was able to compensate for this by integrating a second small sub next to the center channel and applying a little EQ. I now have a much smoother subwoofer response at the primary listening position.
Next up was to do full-range measurement of the response at the listening position. Below is a REW plot of subs plus center channel from 15-20k (black) and subs plus L+R mains (magenta). I also measured L and R separately and they both overlay onto the magenta L+R graph (data not shown).
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Yikes!! :yikes:
As you can see, my previously identified mode of 38-40Hz appears to also rear its ugly head at 10 times the frequency. To map the 40Hz mode spatially, I played a test tone and walked around the room with my SPL meter. There is a standing wave across the width of the room, with its null at the listening position, and a peak along each L/R wall. Spatially, it is one giant cosine wave with the left wall representing x=0 degrees and the right wall representing x=360 degrees. It doesn't matter where you stand in the length dimension - you can walk the length of the room in a straight line along the null or one of the peaks and the sound meter doesn't change.
The room is shaped kind of like a barn with the back torn off - in back, there's an 8ft x 10ft opening to the kitchen and beyond to the rest of the house. The ceiling is vaulted, but symmetrical. The right wall has a fireplace and two windows so I can't do much there. The left wall is solid sheetrock - I could put some absorptive devices there but I know that 400Hz is close to the lower limit of what typical absorptive panels (like OC703) can handle.
What about diffusors? Is this hopeless?
With my large subwoofer in the only WAF-friendly location, I found a large cancellation at around 40Hz in my listening position. I was able to compensate for this by integrating a second small sub next to the center channel and applying a little EQ. I now have a much smoother subwoofer response at the primary listening position.
Next up was to do full-range measurement of the response at the listening position. Below is a REW plot of subs plus center channel from 15-20k (black) and subs plus L+R mains (magenta). I also measured L and R separately and they both overlay onto the magenta L+R graph (data not shown).
Yikes!! :yikes:
As you can see, my previously identified mode of 38-40Hz appears to also rear its ugly head at 10 times the frequency. To map the 40Hz mode spatially, I played a test tone and walked around the room with my SPL meter. There is a standing wave across the width of the room, with its null at the listening position, and a peak along each L/R wall. Spatially, it is one giant cosine wave with the left wall representing x=0 degrees and the right wall representing x=360 degrees. It doesn't matter where you stand in the length dimension - you can walk the length of the room in a straight line along the null or one of the peaks and the sound meter doesn't change.
The room is shaped kind of like a barn with the back torn off - in back, there's an 8ft x 10ft opening to the kitchen and beyond to the rest of the house. The ceiling is vaulted, but symmetrical. The right wall has a fireplace and two windows so I can't do much there. The left wall is solid sheetrock - I could put some absorptive devices there but I know that 400Hz is close to the lower limit of what typical absorptive panels (like OC703) can handle.
What about diffusors? Is this hopeless?
so I can't do any more measurements until I get it squared away.
