Please help: Subwoofer question

[Woochifer]

That particular B&W model is a sealed design (one of the few options of that kind in the sub-$500 range), which means that the bass will potentially extend lower than the more common ported designs. It also means that the lower frequency dropoff will begin sooner, but that dropoff will occur more gradually. In a nutshell, a sealed subwoofer theoretically gives you deeper bass extension but the sound gets softer sooner.

A similarly designed ported subwoofer will have higher bass output up to the port frequency, and then drop off very rapidly thereafter. Subjectively, a lot of people like to generalize that sealed designs are more well suited for music than home theatre because that more gradual dropoff in the bass response at the lower end is more natural sounding. Generally, ported designs will give you higher SPL output because they are more efficient, but they are also more difficult to design correctly because the port opening and the interior volume need to correspond. If impact with home theatre explosions are what you want, a ported design might give you of that visceral grunt. But, the tradeoff is that it might not sound as tight if it's not done correctly.

It could very well be that your subwoofer's not designed to deliver the kind of bass that you want. However, I would try a few optimizing steps before you go trading in your subwoofer. First of all, where you place the subwoofer makes a huge difference. Corner placements will reinforce the bass and give you the most SPL output.

Also, you should get a SPL meter and measure the bass output using the wideband test tone on your receiver. Make sure that the levels match the mains (and a lot of other subwoofer experts on this board recommend a level 4 db higher than the mains).

In addition to using a wideband test tone to measure the overall level, I would invest in a test tone CD and do some measurements at specific frequencies. That way, you'll identify where and if you have severe peaks and/or nulls, and these are more a consequence of your room acoustics than the subwoofer itself. If you find that your room is causing nulls to occur from your listening position, then you need to move the subwoofer somewhere else, preferably into a corner, because the waves are cancelling each other out at that precise location.

If you find large peaks, then that's causing boominess and bloated sounding bass, rather than bass that's full and even sounding. The way to correct these peaks is through either bass traps in the corners of your room or using a parametric equalizer, such as the $120 Behringer Feedback Destroyer. I use a parametric EQ and it was very effective at eliminating the peaking that I got with my subwoofer (also a sealed design). After making the corrections, the bass now sounds very well integrated, but with the deep impact intact.

If you trade in your sub for a larger ported model, I would definitely get the parametric EQ anyway because the more output you get in the lower octaves, the more likelihood that you'll run into a major room induced peak.