A square speaker is disclosed having a novel surround with a novel rounded corner design and with a magnet assembly and former sized, shaped, and arranged to exploit the increased excursions enabled by the novel surround. The arcuate portion of the rounded corner features smoothed trapezoidal circumferential undulations of the radially outer portion and an extension pad forms the arcuate portion of the radially inner portion of the rounded corner. An apex groove separates the inner portion from the outer portion. Tapered protrusions of the outer portion flank the smoothed trapezoidal circumferential undulations. The rounded corner is bounded by edges making angles of between 20 degrees and 40 degrees (preferably about 35 degrees) with straight sides of the square surround. Most of the outer perimeter of the entire inner flange adjoins the inner portions of the rounded corners. Significant increases in volume displacement per speaker size are achieved.