In Reply to: Subwoofer placement posted by airtime on October 9, 2016 at 08:55:31:
Those are just about the worst dimensions you could have because the modes associated with all 3 room dimensions will occur at approximately the same frequencies. Given those dimensions, you will most likely end up with large peaks at 50 Hz and 100 Hz. One option you have is to set the subwoofer's crossover low so that it only operates below the room's modal region, e.g. at 40 Hz so that it doesn't make your room mode problem worse. If you want to run the sub higher, I would suggest a combination of changing placement and using equalization.
First, if you can place the subwoofer at the midpoint of one of the walls, it won't excite any axial modes associated with that room dimension. That is because the midpoint is an anti-node, so the sub output will have a null at the frequencies of those axial modes. Note this won't completely eliminate the problem because you still have modes at the same frequencies associated with the other room dimensions, but it will reduce it. If you can afford another sub, and you can place it on the opposite side of the room at the midpoint of the opposing wall, then you can eliminate the axial modes of a second room dimension. This is what I do in my room. If you can raise the sub(s) off the floor, that will probably help too.
If you have some flexibility to adjust the placement of the main speakers or the listening position, you can move one or both of them to be in a cancellation null at the frequency of a mode.
In general, the more you can mitigate the modal problems through placement, the less equalization you'll need, which is a good thing. Leaving the sub in the corner and using only equalization to address the problem will require a very deep notch filter to get rid of the boom. I've been down that road before and was never happy with the results. With bass EQ, I don't like to use more than a 6 dB cut. Any more than that and bass notes seem to go kind of missing.
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Follow Ups
- RE: Subwoofer placement - Dave_K 09:26:58 10/10/16 (0)