Null Spot (1 Viewer)

[ElectricL3af]

Hi, I don't know why, but there is a null spot for bass in the central sitting spot of my room. I use two different subwoofers, the Infinity R12 and the Polk Audio PSW303. My receiver is the Yamaha RX-V683. I've messed around with settings and rotation to see what I can do. I don't really have different spots that I can put the subs. The central spot is obviously on the couch in front of the center speaker. What can I do so I can actually hear bass in that position? I can move 2 feet to the right or left and hear bass just fine.

 

[JohnRice]

If you can't move the subs, then you may just have to turn one of them off, since they seem to be canceling each other.

I looked at the subs, and the Infinity has a phase switch. Try setting it to the other setting and see if that helps. Otherwise, if your receiver has distance settings for the subs, you can experiment by changing those, but only for one sub. The receiver's calibration might help, but I kind of doubt it has calibration of the level that will help with this particular problem. It can get complicated, but those are some suggestions to start with.

 

[Wayne A. Pflughaupt]

Sounds like you have a really small room.

It’s just acoustical physics. Bass “chases” boundaries, and the dead center of any room with parallel boundaries is a kind of “dead zone,” where the bass is very weak. Move from that position towards any boundary, perceived bass levels increase.

Certainly, try all of John’s excellent suggestions. If nothing helps, just increase the level of the subs.

Regards,
Wayne A. Pflughaupt

 

[ElectricL3af]

Sounds like you have a really small room.

It’s just acoustical physics. Bass “chases” boundaries, and the dead center of any room with parallel boundaries is a kind of “dead zone,” where the bass is very weak. Move from that position towards any boundary, perceived bass levels increase.

Certainly, try all of John’s excellent suggestions. If nothing helps, just increase the level of the subs.

Regards,
Wayne A. Pflughaupt

Ok, thanks. The room size is about what you see there except I was standing like 4 feet from the back wall. As you can see, the left 'wall' opens up into another large room. So the room is not closed. I know turning off one sub did not help at all, and messing with the phase settings on them both also didn't. I'm always nervous to increase the gain of the subs because I don't know how much they can take.

 

[jcroy]

Sounds like a stationary zero spot in a "standing wave".

https://en.wikipedia.org/wiki/Standing_wave

Basic physics + mathematics of wave motion at its core.

 

[Wayne A. Pflughaupt]

The room size is about what you see there…
As you can see....

I don’t see a picture.

. I'm always nervous to increase the gain of the subs because I don't know how much they can take.

Most subs these days have built-in limiters. Even if they don’t you’ll when they reach their limits – it will make rude noises.

Regards,
Wayne A. Pflughaupt

 

[Dave Upton]

An alternative option is to do some bass trapping. This can often help with these nulls, though won't eliminate them entirely. Here's a cost effective example: http://www.ayoung.ca/basstraps.php

 

[JohnRice]

Ok, thanks. The room size is about what you see there except I was standing like 4 feet from the back wall. As you can see, the left 'wall' opens up into another large room. So the room is not closed. I know turning off one sub did not help at all, and messing with the phase settings on them both also didn't. I'm always nervous to increase the gain of the subs because I don't know how much they can take.

You simply haven't provided enough information. The problem is most likely what JR mentioned, but I'm not aware of any way to address it without more detailed info of the room and locations of the subs. Subwoofers require flexibility in placement, because their interaction with the room is complicated. You can't just put them wherever and expect them to perform. A very basic rule is you don't want them equal distance from any two surfaces. In general, you want as large a difference in the distance from every wall surface as possible. You also don't want radiating (driver, port) close to a wall. So, you can often place one side of the sub close to a wall, as long as it isn't radiating from that side. That link above helps get the idea across what subwoofers send out waves that reflect around the room, and can emphasize or cancel themselves out. Often moving a subwoofer just a few inches, or a foot, in the right direction makes an enormous difference.