Speaker unit

A speaker unit comprising:

• a speaker frame;
• two membranes arranged in the speaker frame, a first membrane of the membranes having a major acoustic radiation direction substantially perpendicular to a major plane of the speaker unit, and a second membrane of the two membranes having a secondary acoustic radiation direction different from the major acoustic radiation direction;
• two drive units positioned within the speaker frame and attached to the first and second membranes, respectively,
• wherein the first and second membranes are arranged in opposite configuration in the speaker frame and the secondary acoustic radiation direction is opposite to the major acoustic radiation direction,
• wherein the first and second membranes are coaxially aligned along the major and opposite second acoustic radiation direction, and
• wherein the two drive units are positioned coaxial to each other at the same height in the speaker frame and laterally displaced from the membranes in a side-by-side arrangement therewith;
• and
• an acoustic duct providing a closed acoustic channel from the second membrane in the secondary acoustic radiation direction to a secondary surface of the speaker unit, the secondary surface being located in a same plane as the major plane of the speaker unit.