frame|right|Bass reflex [[Loudspeaker enclosure|enclosure schematic (cross-section).]]
220px|right|thumb|RCA bass reflex [[shelf stereo speakers.]]
A bass reflex system (also known as a ported, vented box or reflex port) is a type of loudspeaker enclosure that uses a port (hole) or vent cut into the cabinet and a section of tubing or pipe affixed to the port.