Abstract: Critical damping of a dynamic loudspeaker is achieved by placing a supplemental, short circuited coil of similar configuration and mounting alignment to that of the drive coil in rearward adjacency thereto for being biased into the flux gap during extreme forward excursion of the speaker cone and drive coil. External circuit elements connected to the supplemental coil provide desired impedance for damping particular resonant frequencies.High ambient-temperature performance capability for functioning of a speaker in a public address system or to sound an alarm during a fire is provided by use of an aluminum cone diaphragm and a plastomer coated glass cloth surround.