[nerdoldnerdith]

Hi everyone,

My room is already treated with porous absorbers and diffusion, so the last thing I'm looking to do is tame the remaining room modes with frequency-specific membrane bass traps. I haven't gotten a lot of good information on where exactly to place these once I acquire/build them. I played the offending frequencies and walked around the room to hear where they are loudest, but some of these locations are far away from the main listening position and two of them are actually in an adjacent hallway. Will putting the membranes in the hallway help with these modes, or should I try to put them on more reflective surfaces closer to the listening position?

[JLM]

Best to use multiple subwoofers as per Floyd Toole, Earl Geddes, and Duke LeJeune.  Suggest reading Toole's "Sound Reproduction" (either edition) to learn about how huge bass peaks/dips are inherent to any room.  I have ten GIK 2ft x 4ft 244 panels plus three randomly filled tall bookcases that serve as adjustable/casual diffusors.  Six of the panels are "full range" and located at first reflection points.  The other four panels are "bass traps" (membrane), straddling the front corners. 

[youngho]

It's more a little tricky to answer your question. I would assume what you're asking is about the room modes that are causing problems at the listening position, which are still causing a problem after parametric equalization. The presence of a door or window tends to extend the effective length/width of the adjacent dimensions. However, from what you've written, you're trying to address the effects of modes outside of the listening position, since you wrote that you're considering "these locations [that] are far away from the main listening position." If they only cause problems far away from the listening position, why does it matter? Or are you concerned about second-order modes?

Probably easier to address your questions with diagrams and measurements.