Subwoofers produce very long wavelengths — a 60Hz tone has a wavelength of approximately 5.72 metres (18.75 ft). Because standard speaker cabinets are much smaller than this wavelength, a single subwoofer radiates energy nearly omnidirectionally at low frequencies. This means bass energy goes everywhere equally — towards the audience, behind the stage, into the building structure, and towards performers.

Array techniques exploit acoustic interference to shape this otherwise uncontrollable pattern. By spacing multiple subwoofers apart at specific fractions of a wavelength (typically λ/4), you can create a cardioid (heart-shaped) pattern that produces significantly more bass energy towards the audience while cancelling energy behind the array by 10–20dB. This dramatically reduces stage wash, monitor bleed, and structural loading on the venue.

Gradient arrays use a rear-facing subwoofer delayed by 1/4 wavelength. End-fire arrays use front-to-back spacing equal to 1/4 wavelength with delay on the rear cabinets. Broadside arrays use vertical stacking to increase gain at long throw distances without changing the horizontal directional pattern.