The SB-118F single 18" and SB-218F dual 18" subwoofers are designed specifically for low frequency enhancement in cinema applications, especially for low frequency content of the surround channels using bass management techniques. A common application is suspending these enclosures from the cinema ceiling in proximity to the wall mounted surround loudspeakers for which the SB-118F/218F provides low frequency enhancement. The SB-118F/218F covers the frequency range from 37 Hz to 230 Hz. The custom 800W, 18" transducers were developed especially for cinema use. They feature large 4" (101mm) voice coils and a multi-vented pole piece to ensure cool operation, even at high power levels. Cooler temperatures increase transducer lifespan and decrease the problem of power compression at high power.