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An argument for multiple subs

Hello Apokalypse,

As you've probably noticed, most subwoofers are designed for loudest-deepest-possible-bass in the smallest-possible-box. That's great for home theater, but not necessarily the best set of priorities for music reproduction.

My suggestion is to get two less expensive subs, preferably with 4th order low-pass filters. Avoid models with ultraheavy cones - in my experience they tend to sound like rumblemotors instead of like music.

Let me explain my reasoning behind suggesting two subs:

Consider the situation with a single subwoofer. There will be one path length from the sub to the listening position. There will be another path length from the sub to the wall behind you and then back to the listening position. At the frequency where the path length difference is equal to one-half wavelength, the energy reflecting off the back wall will arrive 180 degrees out-of-phase with the direct energy and a cancellation dip will result. At the frequency where the path length difference is equal to one wavelength, the reflection will arrive in-phase and a reinforcement peak will result. There will be additional peaks and dips at harmonic intervals, and others related to alternative reflection paths in the room.

Now the problem in the bass region is not that there are too many of these path-length-related peaks and dips; it's that there are TOO FEW of them! They are spaced widely enough apart to be audible. At midrange and high frequencies we also have path-length-related peaks and dips, but they are so many and spaced so close together that they are not heard as separate and distinct peaks and dips.

I propose using two (or more) subs, scattered around the room in an attempt to maximize the variance between their respective peak and dip patterns. For instance, maybe place one sub near (but not in) the front left-hand corner, and the other sub along the right-hand wall a little bit behind the listening area. A fourth order low pass filter will help conceal the location of that second sub. Barring that, cross over any subs that aren't near the main speakers as low as possible.

There will be a tradeoff: One supersub will go deeper than two half-the-price subs, and probably play louder too. You must resist the temptation of ultralow and ultraloud bass - for it usually comes at the expense of sound quality.

The multisub approach will give you a low frequency sound field more reminiscent of what you'd get in a much larger room. What I'm proposing is an acoustic solution to what is fundamentally an acoustic problem. Equalization would be an electronic solution, and may or may not be more practical - but in this case is probably out of your price range.

Just my $.02. Best of luck to you.

Duke

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