Bass is designed to cover the frequency range 20 Hz-350 Hz.
It is based on a dynamic speaker Scan speak Discovery 26W/4558T00 in a closed box with an internal volume of 30 liter.
Here is a simulation with BoxSim.
The frequence response is far from linear in the area 20 Hz – 350 Hz and needs compensation.
Measured frequency response
The following two measurements are performed with REW.
This measurement shows the raw near field speaker response.
This measurement shows the near field response after the low pass cross over filter (LR4).