Low bass output in vented systems come from the port(s). High levels of low bass require a lot of air to be moved. If the port's crossectional area is not large, air velocity gets very high, resulting in turbulence (port chuffing) and compression.

For a given enclosure volume, putting in a larger port means a longer port length to tune the port to the same frequency. In order to fit two 4" ports into an enclosure the size of the HO, we need to bend the ports. However, if not bent properly, the bend will cause premature onset of turbulence, negating the purpose of going to a larger port.Our patent pending bent port technology ensures that our bent port performs as well as a straight port equivalent.

The reason for variable tuning is that all subwoofer designs, especially consumer-level subwoofers, involve tradeoffs in design. You cannot have a small subwoofer that goes very low, plays very loud and costs very little. Traditionally, the engineer decides what tradeoff he or she thinks is best for the consumer. The consumer has to take it or leave it.

The VTF-3 HO changes all that. It allows you, the user, to choose the tradeoff. If you enjoy music that is loud but does not have much deep bass, set the VTF series for maximum output. That way, you get maximum dynamic range with the lowest distortion. If you like music with deep bass, set it for maximum bass extension to reproduce the deep bass accurately. You can even switch between the two modes depending on what you play. That means effectively you get a subwoofer that can play loudly, and can play low, all in one, at a reasonable price!