Quote:
DrWho wrote:
 If neither of the above approaches work, then your best bet will be to reposition the subwoofer (in fact, you might as well just start with moving the subwoofer). Don't forget the option of moving the listening position too. The position of nulls in the room are mostly the result of the standing waves that build up...moving the speakers around doesn't change the dimensions of the room, which is to say that the standing waves generally want to happen in the same location. For instance, take a measurement in the rear corner of your room and note how different the response is... |
I agree. The mains and sub both have a nasty dip at nearly the same frequency. Nothing short of moving speakers is going to fix that (or as the Dr. suggests, moving your seats out of the area where that occurs). If your mains and sub are in about the same location, it is probably the same surface reflecting a wave that is weaker but out of phase with the direct waves from the main and sub at your listening position. That suggests the possibility of having to move both mains and the sub to fully eliminate the dip.
The worst thing you can do is put mains and a sub centered on a wall facing the wall opposite them, and then sit between the two walls. Unfortunately, that's a typical room layout. Say the room is 20 feet from front to back and you are sitting five feet from the back wall. The direct wave will travel 15 feet to your ears. The reflected wave will travel 20 feet to the back wall and bounce forward to your nears, an extra 10 feet. Unfortunately, that 10 feet will put the reflected wave out of phase with the direct wave at your seat at about 55 Hz. Likewise, if your sub is to the right of your seating position and there is wall 5 feet to the left, the same result occurs. The further you are from the back wall, the lower the frequency where the dip appears (and vice versa).
One of the best locations for a sub is the corner nearest your mains (so long as you aren't sitting in the diagonally opposite corner. Where that doesn't work, put your sub 1/3 the distance from the corner to the left of your mains or the corner to the right of your mains, but not where you will be sitting directly in front of it. You want the sub well off to the left or right and at the 1/3 or 2/3 point along the wall (assuming you want the sub on the same wall as your mains). If the sub is on a side wall, the same rule applies, 1/3 or 2/3 and not on a perpendicular from your seat to that wall.
If the sub can be away from any wall, that's also a potential solution, but in that case the sub should be 1/3 1/3 ... that is, 1/3 the distance from each closest wall to the opposite wall. And, again, you don't want to sit on a perpendicular between the sub and a wall. That is, you don't want sound passing directly past your ears, hitting a wall at 90 degrees and bouncing back to your ears. You will have a dip at the frequency where the distance to the wall and back is 1/2 wave length.
At least these are starting points.
Good luck. And, it does take some luck!
Let us know how it's working out.
Harrison