Lupo,
I tested traps behind my speakers to see if they would alleviate SBIR.
No visible result. However, the test is worth repeating, in the light of these newly developed view manipulating skills!
I work around it. I test and move each speaker in all axes, to get the most even bass. I double check the combined response by RMS averaging and testing again with both driven. Basically I am trying, on a result basis, to use some of the problems to alleviate others.
Bass null in my new treated room, help! w/pics
Quite often I end up using a LF boost on the speaker, or moving the speakers closer to the front wall, occasionally almost touching it. I have seen it mentioned elsewhere (by SAC I think) that SBIR is amenable to correction by Eq. An interesting and largely overlooked point I reckon.
A mirror, measuring tape, and calculator, are of course useful, but Thomas Barefoot has done us a great favour by writing a 2D Wall Bounce calculator. Good fun.
John Sayers' Recording Studio Design Forum • View topic - Wall Bounce Calculator 2D
Clarification-
Originally Posted by DanDan
I believe what we are seeing here is an illustration of how different measurement methods yield different results.
Quote:
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Almost. We used the same measurement method! This goes to show that the same measurements are up to different interpretations depending on the selected observation tool.
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I was referring to my original test. The one using a third octave band of pink noise at 125Hz. This yielded a different result. I don't think the lack of difference can be attributed to 'full bandwidth' measurement. The 85dB SPL was way ahead of background and was limited to one third of an octave.
I fully accept that comb filtering is a full range issue. The OP however asked about a singular one. Quite valid and natural IMHO. I reckon the LF dip is the most potentially significant because music has a lot more energy at LF.
Also the bandwidths of the higher frequency spectacular dips are very small.
I wonder are they that audible? You need to try that flanger test blindfolded!
DD