I have my sub positioned near my fireplace in the corner, but it's not a true corner. The wall running behind the sub is 90 degrees, but the wall running beside the sub is 45 degrees. I've found that if I'm not directly facing the sub, there's no bass at all anywhere in the room. What would cause that to happen?

Have you tried this AV Tip of the Month?

Cheers!

Yeah, I've tried that, it doesn't matter where I place the sub, if it's not facing the listening position, you can't hear or feel any bass at all. Unfortunately, I don't have a true corner to put the sub in, so the levels have to be higher than I like. If I turn the sub down enough where I can't tell where it is, the bass is all but gone. If I turn the volume up to the point where the sub is starting to sound decent, it's distracting because you can hear the sub seperate from the front speakers when listening to music. I can't figure out for the life of me what I'm doing wrong, or how to correct it.

Hmm... Have you tried to calibrate the sub levels using an SPL meter (RadioShack etc) and low-pass/high-pass pink noise from either the receiver or one of those test CD/DVDs? I may be mistaken, but the SPL meter might disagree with your expectation for a "normal" amount of bass.

Confused, I'm likewise, because the bass below about 100hz is essentially non-directional and it shouldn't make the slightest difference whether you're facing the sub or have your back to it. The best corner for the sub is generally the "tightest" one, i.e. the one farther from a doorway or other opening. Also, the bass shouldn't be obvious as a separate element, it should give the impression that your mains are suddenly putting out more bass. I wonder if, as sushi may have implied, you're simply expecting too high a level of bass and if the level where it's "all but gone" isn't in fact a normal level.

Is the crossover on your sub turned down too low?
Perhaps you are missing the sub sounds b/c its being limited to a very small, lower end range of frequencies.
Its just a thought.

Thank you very much for your input guys, here's what I can tell you. I don't have a meter, so I can't adjust it that way. When I say the bass is gone, I really do mean it's gone. I turned off the sub to see if it made a difference, and it didn't, it sounded the same with the sub totally turned off. My receiver's crossover is set to 100hz, but the adjustment on the sub itself for the crossover is turned all the way up, to 120 or 130hz. Perhaps that is the problem? I should adjust the crossover on the sub to 100hz as well? I've tinkered with sub placement over the last few days, and the only reasonable conclusion I can draw is that where I usually place the sub (between front speakers and entertainment unit) is one large null spot. I moved the sub near a corner close to the listening position and I had to turn the sub volume down significantly to take away the fatiguing bass sound it was putting out.

No,with your Marantz crossing to the sub below 100hz, the sub crossover should be left all the way up so that it doesn't interfere with the receiver crossover. Setting it around 100hz would, if anything, reduce the bass.

Still puzzled; your usual corner doesn't sound ideal, but it should be decent. Is the other corner behind the speakers usable and any better? Is the corner near you that you mentioned trying okay after you turned the sub volume down?

...And you have tried both positions of the phase switch on the sub, right?

Cheers!

I only have one corner to use, and that's not really a corner, and its where the front speakers are. The corner that's located closest to the listening area is too far for the cable to reach, but when I had the sub near that corner, there was way more bass, actually far too much bass. I've tried the phase switch at every location, and I don't audibly detect much of a difference between the two.