I built some custom
Ethan Winer midbass/upperbass/midrange traps for my listening room, covering the front wall behind the speakers.
Cost was under $200, and took about a week to construct.
The improvement in overall bass clarity and impact is striking.
YMMV
1khz Reference level = 75db
Hz--------w/o traps---w/traps
200-------72---------79 (+7db)
160-------69---------76 (+7db)
125-------68---------75 (+7db)
100-------68---------74 (+6db)
80--------69---------74 (+5db)
63--------62---------68 (+6db)
50--------67---------68 (+1db)
40--------75---------76 (-1db)
31--------77---------76 (-1db)
25--------73---------73
20--------63---------63
pix of traps