The Episode Impression bandpass subwoofer pairs with our Impression in-ceiling speakers to allow dealers to work side-by-side with interior designers to provide excellent total-home sound. This 6 1/2" sub uses a bandpass box design, which allows the sub to produce deeper bass through a smaller opening. The front of the sub fires into a chamber that’s tuned by a port, which acts as a low pass filter for incredibly low and efficient bass.