Abstract: Methods and apparatus are contemplated for providing a primary audio signal containing audio content to one or more primary loudspeakers; and delaying a secondary audio signal containing the same audio content to one or more secondary loudspeakers, wherein the delay is such that respective sound waves originating from the primary and secondary loudspeakers arrive at a location nearer to the secondary loudspeakers without causing sound smear.

Abstract: Methods and apparatus for producing first and second drive signals from an input signal such that each drive signal is about 180 degrees out of phase with respect to the other; variably altering at least one of the first and second drive signals such that their respective magnitudes may be unbalanced to a varying degree; and producing an output signal from the first and second drive signals such that it includes harmonic distortion when the first and second drive signals are unbalanced.

Abstract: A portable sound unit is shown having a central case and one or more speakers. Each speaker has tongue rails around a portion of its circumference. The central case includes an openable lid permitting access to sound equipment contained within the central case. The central case has openings at either end when the lid is closed and grooves inside a portion of the central case near each opening. The grooves receive the tongue rails on the speaker when the lid is open. Upon positioning a speaker in the grooves in the central body, the lid may be closed, thereby securing the speakers to the central case. When the speakers are separated from the central case and electronically coupled to the sound equipment, the opened lid may serve as a lectern.