Well, I think you ( and I ) have a Speaker Pudding Project and it could be done with a speaker switched with the filters installed and could be played with the filters on or off---I think Mike Creek or somebody was doing this exact thing on a production 2 way ----I have 2 sheets of Baltic Birch and will look into to the design and report back as to what I would need help with---the filter construction doesn't look super hard but I am a novice too---more later Jim