Sub set: Velodyne's SMS-1 lets you see your subwoofer and your room's characteristics on your TV, and you can adjust the sub accordingly.

EQUALIZE IT

There's a ton of computer-processing horsepower lying around in modern home-theater systems, and many receivers tap into this to perform some equalization. And when you hear "EQ," we're not talking about those 12 slider bands that you arbitrarily positioned into a flying V to increase your system's thump and sizzle. Modern A/V systems take an advanced approach to equalization using microphones, test tones, multiple positions, and computer processing to make measured, calculated decisions that generally lead to better sound.

Velodyne's Joe Finn commented, "Quality room analysis and the sparing use of equalization can help considerably to put the music back in balance by taming the exaggerated frequencies." Gough explained the approach taken by B&W for its new flagship sub, the DB1: "The response of the subwoofer is measured at a number of points throughout the listening area, and the results are analyzed by an intelligent algorithm that extracts the relevant offending resonances and changes the response such that the overall response is more even. Is the sound made 'perfect' throughout the listening area? Unlikely. Is it better than it would otherwise be? Absolutely. Is it better than if the user had been left to do the interpretation? Almost certainly." Audyssey and Velodyne both offer some terrific tools for improving bass response with any sub in any room.

Audyssey's new Sub Equalizer takes an automated approach, whereas Velodyne's SMS-1 puts control in the user's hands. Audyssey's Jim Merk said the company's system "measures the entire listening area, identifying timedomain problems." [For more on Audyssey's bass EQ solutions, see the test report of the SVSound AS EQ-1 subwoofer equalizer - Ed.]

Velodyne's SMS-1 offer eight fully parametric EQ points for adjusting the bass and uses an onscreen display that allows you to see the effect of any adjustments made. "This is a huge help in being able to take corrective action on the parts of the bass spectrum that are being affected by the room," Finn said. "Before making any EQ adjustment, you can try changing the sub's position in the room, or changing the crossover point or slope, or adjusting phase or polarity. Since you see the result, you may be able to get smooth, even bass without using any EQ at all."

UNRATTLE IT

Few things are more distracting than trying to watch a movie and hearing an orchestra of buzzes and rattles emanating from objects around the room. "Use one of the test tone programs to sweep the room and see what's shaking," offered Sunfire's Eric Harper. "You'll be surprised what you uncover - ceiling tiles, wall sconces, decorative posters, HVAC registers, etc. Whatever isn't nailed down probably should be. A roll of foam tap or gasket-type material will be your best friend as you seek and destroy those pesky rattles."

JL Audio's Carl Kennedy suggested, "Use lots of silicone and little rubber bumpers. One of the most common mistakes - not just with in-wall or custom subwoofers - is that people don't listen to the room itself. Listen to the buzzes, rattles, and things that are resonating. Take care of as much of these distractions as possible and it will make the entire system sound better and add definition."

Another fix is to decouple the subwoofer from the cabinet. If possible, remove (cut out) the bottom of the cabinet where the sub sits and place the sub directly on the floor. This will help to eliminate some of the direct sound transmission. If that isn't possible, place the sub on a thick rubber mat or heavy rubber stops.

And that's that. Hopefully you've been able to glean something useful from this "better bass" series and are now enjoying the best bass your system and room are capable of producing.

John's first home theater purchase was a giant, incredibly wife-unfriendly subwoofer back 1995. He began his career as a custom installer in 1998 at Custom Theater and Audio in Murrells Inlet, South Carolina, where he still works. He welcomes any suggestions for solving the problem of his Trinity Signature Reference subwoofer trying to vibrate windows out of their frames.