The SMS-1 room correction system is designed for use with subwoofers to help tailor the sound of the subwoofer perfectly to the shape of your room. With auto setup features, it becomes very easy to perfect the sound of the bass response of the subs in your room for maximum depth and volume without thumping, one note bass distortion.
An excerpt from a satisfied Amazon reviewer:
"...this unit really did improve the response from my subwoofer and what I have now is noticeably cleaner and tighter bass.
"What I like about the Velodyne: It is very easy to use, the build quality is excellent, and it is very flexible and versatile when it comes to making adjustments when tuning the bass for your room. An on-screen display and a continuous sweep tone shows you what the bass response is at the location where the microphone is placed. The SMS-1 has an 8-band parametric equalizer (meaning you can adjust the middle frequency of each of the 8 bands to really tailor the sound), continuous phase adjustment, a polarity switch, and easily adjustable controls. Audiophiles will know what I am talking about. If you aren't familiar with these terms, just know that this product is very powerful in its ability to achieve a flatter bass frequency response curve. As you fiddle around with the adjustments, you can see the results in real time on your television screen - what could be better feedback than that?
All in all this is an excellent unit. No matter how good a subwoofer is, your room plays a significant role in the response. The Velodyne overcomes limitations imposed by your room and/or the sub itself and improves the listening experience.