Massive low frequency cancelation (1 Viewer)

[Jonathan T]

There's a HUGE null in the middle of my room, right where my listening position is. Now, I was using 2 speakers and no sub, so I'm assuming that the speakers were canceling themselves out. Furthermore, it wasn't just on the horrizontal plane, but also on the verticle plane. When I sit down, the bass comming from the speakers is not nearly as loud as when I stand up, the difference is barely 1 foot. So, I'm going to get a sub (parts express DVC 12 in a 2.0 cubic foot box) when I order a pair of HE10.1s. I found the best place for the sub (by moving one speaker, while the other was disconnected, to the center of the room and walking around to see where I get the loudest bass). Would I still have the cancelation problem with the sub? My room is about 14X11X7. Xover would be about 80 hz.

 

[Jim A. Banville]

The center of a room (as far as height and width) with parallel walls and no openings will have a NULL region for certain bass frequencies no matter what you do :frowning:. We can't change the laws of physics. Now, varying walls construction, varying wall/ceiling geometry, windows, door and other openings will tend to reduce this null.

 

[Jonathan T]

I can open the windows when it isn't raining/snowing or too cold. I also have a lot of funiture. 2 desks, a bed, a dresser, a night table and some shelves. The largest desk is in a corner right next to the bed and the night table. Seems the best place for sub. I'll try it there and see what happens.

 

[PaulT]

Jonathan
Try plugging some measurements into this program:
http://www.pvconsultants.com/audio/reflection/rrc.htm

Here's a room mode calculator from Harman Kardon:
http://www.harman.com/wp/xls/Room%20...Calculator.xls

 

[Jonathan T]

Thanks paul, I'll check those programs out then I get home.

 

[Jonathan T]

The programs are just telling me what I thought the problem was. I guess I'll just have to experiment (when I get my sub built) and see what happens.

 

[PaulT]

Glad you got the programs. It's easier to plop in the numbers rather than dragging the speakers around.

Go back to the Harman site and download some of the White papers:
http://www.harman.com/wp/index.jsp?articleId=default
specifically the Subwoofer one and the 3 part loudspeaker series.

There are some points of interest about Sub placement that you may find helpful.

 

[Doug_B]

The sub will provide latitude due to the ability to move it (how much depends on your room layout, preferences, etc). If there are still issues after getting the sub, you may benefit from using an equalizer before the low freq signals get to the sub. In my case, the Behringer Feedback Destroyer that I use works great for my room; might be the best value component in my entire setup.

Doug

 

[Jonathan T]

Paul, thanks for the program, I'm playing with it now.

Doug, I'll get a BFD when possible, just need to get some $$$ first.