Seas prestige H9945 SP22R - Passive Radiator 8"

Manual 

SP22R (H9945) is a passive radiator intended for use as an alternative to the port in a bass-reflex cabinet, together with an active woofer of similar size or smaller. In many applications, the traditional bass reflex port may produce high-speed air noise or even have poor effect due to a small port area or a large port length. In such cases, a passive radiator may bring about an improvement. The passive radiator cone is equipped with an M4mm screw to which you can easily attach the added mass. For optimum performance, the passive radiator should be mounted vertically (with a horizontal cone axis). This is especially important when a significant additional mass is used.

Tip: As a general rule, the passive radiator(s) should have at least double the displacement of air (Vd) as the active woofer(s)/subwoofer(s) in the system.