Please help with notch filter on B&K pre-amps

I recently purchased a B&K Reference 30 pre-amp and am trying to figure out how to use the notch filter in order to eliminate some problems with bass within my room. The manual isn't much help.

I can get the test tones to work and have found the problem frequencies, but am not sure what to do next.

What does the "notch range" do?

Any help would be greatly appreciated.