The TN series is inspired by Tom Nousaine, one of the most respected subwoofer reviewers. He introduced a new criterion for subwoofers: square footage of floor taken up by the subwoofer. The TN series takes up less than 0.8 to 1.1 square feet of floor space. There are currently two models in the series: the TN1220HO, and the TN1225HO. The TN1220HO extends flat down to 20 Hz at very high levels, while the 1225HO goes down to 25 Hz.