AVS Special Member
Join Date: Nov 2006
Location: Bushnell's Basin, NY
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So, the panels are made of 2x6's at the top and bottom, with 2x1's on the sides? Why muslin only on the back? What keeps the Roxul in? You have then placed them across the front/rear corners of a diagonal room?
You're getting what your design should deliver.
- you started with a good, broad band absorber - the Roxul
- you covered it with muslin and flannel, which reduce absorbance at higher frequencies
- you placed it close to room surfaces, which limits its low frequency absorption
You're getting quite a bit of effect in the 80-400Hz range, right where this design should be absorbing. The high frequency absorbance is likely better with just muslin around the Roxul (flannel's not that porous in my experience), and this type of panel is very effective placed behind the L and R speakers. Hard to predict with diagonal walls, but this placement usually helps flatten the 100-300Hz range where front wall bounce (sometimes mis-termed the Allison effect) has a large effect. I would imagine a corner placement, mounted flat on diagonal surfaces, would make these even more effective.
But I bet you were hoping for some movement on that 52Hz dip...
First, confirm the dip.
Measure repeatedly around that location (your listening position perhaps?) to see the local interference pattern, not just one point. I just did my room, and moving the mic was critical to seeing the whole picture. A dip like this "appeared" at one point in my measurements, just due to a mic position change; no dip in 3 spots nearby so non-issue. I'll move my head.
Next, level match your sub to the rest of your system. I find even a 5dB rise is noticable, and you're a good 10dB higher at 80-100Hz. Once you've got a fairly constant bass SPL level over a region of space larger than your chair, we can talk about residual issues, and how to address those specific issues.
And I'm serious about confirming the dip. Litteral from one shoulder to the other, I get a completely different pattern, and yet another pattern behind and in front of me - 4 locations within 3 ft of each other, 4 curves with different bumps from 40-100Hz... and this in a nearly resonance-free room.