@luisma31 The bottom octave is generally considered to be 20Hz to 40Hz, the second octave 40-80Hz and so on.
80Hz has a bit of a special meaning to subwoofers and the human ear because it is at about this frequency that bass appears omnidirectional to the human ear. This is partially because it takes some time for the ear to register that the bass has occurred. So it does not matter where the woofers are if they are only operating below this frequency; the rest of the speaker system (80Hz and above) provides the location information on those bass notes from their harmonics.
80Hz has a bit of a special meaning to subwoofers and the human ear because it is at about this frequency that bass appears omnidirectional to the human ear. This is partially because it takes some time for the ear to register that the bass has occurred. So it does not matter where the woofers are if they are only operating below this frequency; the rest of the speaker system (80Hz and above) provides the location information on those bass notes from their harmonics.