How do you improve bass response in a null?

How about moving the couch a tad further back. You don't have to muck with speaker placement much and this would change your listening point of perception. Sean
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You didn't state where the sub is currently located. The optimal position for best bass loading is normally in a corner of the room, where there are three adjoining surfaces. Sometimes moving the subwoofer only a few inches will make a significant improvement.

Dbwl,

I read a past post of yours where you heartily endorse REL subs. You've given me food for thought. I'm thinking that the REL might augment the bass better than my current M&K sub. Do you think it's more a matter of location or brand of sub? The M&K has plenty of raw output, but may not integrate as well. Does integration have any bearing on spl level?

Sean,

As you suggest, I've thought about moving the sofa farther back, but then realize that the TV picture would become smaller. However, this might be an acceptable trade-off. It's easy enough to try. I'll let you know the results.

Sdcampbell,

The sub is currently located on right front wall about 3-4 feet from the side wall. Corner location would interfere with a closet door on side wall. I've heard that while corner placement provides more bass reinforcement, it also can add to boominess and standing waves. But as you suggest, maybe I just need to move it a few inches.

In the past I've moved my seating position a few inches, and it never has made a significant difference. Is this the same as moving the sub's location?

Thanks to all for your input.

Both brand and location make a difference for quality and spl. I don't think integration per se has anything to do with SPL (if we're talking about the same definition of integration), but there might be something I'm not thinking of. A Rel sub might not produce a null zone from the same location because they're down-firing (if the M&K is a front-firing sub). Getting a similar sub with more power may not do the trick, if the null zone is caused by by the room structure. The Rels, btw, don't come with the most powerful amps out there. I'd definitely experiment with moving the sub around a little. That's the easiest and cheapest solution.

I had a problem not so much with a null, but rather a peak at 40 Hz. Though I had a bit of a null at 80 Hz, the response of the sub in the room was almost +10db higher at 40 Hz. Moving the sub around did help a little, but didn't come close to eliminating it.

After months of heavy lifting the sub to various points in the room and annoying my family and dog to no end with test tones and sweeps, I decided to try and play with the phase of the sub to see if it made any difference. The usual way to set the phase is to adjust it (usually a switch or knob on the sub) so that you get the loudest response at the listening position, which is what I always did. So just for grins, I decided to flip the phase switch on my sub from the 0 degree position to the 180 degree position. I could instantly hear the 40 Hz peak was either gone or significantly reduced. So I re-ran my test tones and calibrated things again with the phase set to 180.

Sure enough, after measuring it with my Radio Shack meter, the 40 Hz peak was reduced to a 1 db peak. No more boom-boom headaches or seemingly one-note bass. Music and HT sound signficantly better.

Not sure if it will work with your null problem but you may want to try it. My system includes Dunlavy Aletha's and a Velodyne FSR-15 sub. Try it and let us know if it works for you.