The work presented by Santillán [J. Acoust. Soc. Am. 110, 1989–1997 (2001)] about equalization at low frequencies in rectangular enclosures is extended, and topics that remained unaddressed in the original study are treated in this paper. A modification is introduced to the original cost function that leads to a least-squares problem formulation that demonstrates increased robustness, and the multiple-error LMS (Least Mean Square) adaptive algorithm is employed to approximate the coefficients of the equalization filters to their optimum values. Other issues studied in this paper include the dependence of the limits of the zone of equalization on factors such as the damping constant of the modes of the enclosure, the number of sources, and the driving frequency. ©2004 Acoustical Society of America.