The Ultra Tower is a true full-range loudspeaker with usable deep extension to 28 Hz. With the possible exception of acoustic pipe organ music (which can extend to 16 Hz), the Ultra Tower does not require a subwoofer for 2 channel source material.
In home theater systems using the Ultra Tower, a subwoofer is still recommended to handle the redirected bass from the other speaker channels, and the LFE (.1) channel. Refer to the Digital Bass Management section of our FAQ page for more details..