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 for more details.