Huh? Their website says the 18.3 has as much output as two 18.0s.
F18.3 spec:
Variable tuning; 17-23hz, 15-21hz with curved sided option
+/-3db variable from 13-30hz, to 40-150hz, customizable, contact us for more information
124db maximum output at 2m ground plane
F18.0 spec:
Sealed
+/-3db variable from 10-30hz, to 40-500hz, customizable, contact us for more information
126db maximum output at 2m ground plane
So not only does the F18.0 have higher max output, it also goes lower to 10Hz. The F18.3 goes down to 13Hz.
Maybe it's a typo.
