The 1723 Tower S has the added flexibility of plugging different combinations of the 2 ports. With both ports open maximum bass output is guaranteed, but with a higher roll-off point. With one port open, the -3dB point is lower still, but with an increased rate of roll-off. All ports plugged brings the Tower S back to a fully sealed alignment. The Tower S, therefore, delivers a choice of multiple roll-off, output, and damping ‘tunes’ that will suit a wide variety of tastes, room acoustics, and speaker placement.
Please Note: With only a single port open, higher listening levels could generate some port noise (sometimes called ‘port chuff’) from the extremely high velocities of the air within the port. It is therefore not recommended for high SPL listening but may perform quite well at moderate levels.