Originally Posted by audioguy
I'm not sure what "at those locations" refers to. I have had 3 different theaters where each eventually had subs in the 4 corners (all sealed rectangular rooms). In every case, the FR was pretty flat AT THE MLP.. I also helped another individual build his theater, he had a sub in each corner and he, too, had pretty flat FR at the MLP. Is that just good fortune? Or does "at those locations" refer to another spot in the room?
I'm referring to similar frequency response across multiple seats in multiple rows, before any PEQ etc.
At a single seat, it is pretty trivial to get the subwoofer response that one desires. Keep the MLP out of any nulls, put a subwoofer pretty much anywhere you want, and go to work with a DSP. Not much chance nearby seats will sound the same, especially with one sub, multiple rows, etc.
Getting that same smooth response across multiple seating locations absolutely requires the use of a DSP, and depending on the method (Welti-Devantier, SFM ,MSO, Geddes, Lemay virtual sub), some combination of subwoofer location and seating location. In the case of Welti-Devantier, subs are placed in corners, mid points, or 1/4 points. This results in a similar seat-to-seat frequency response across a large listening area. However, because some locations are in the nulls of room modes, and others at peaks, while the frequency response at each seating location will be similar, the response will not be anything close to flat. However, since each seat is similar, you can now employ PEQ and it will affect each seat in a similar way, and you can improve the frequency response equally across quite a large listening area.