Audio Control Subsonic filter modules
The audio shops that sell them around here charge $30 for a module, so I finally built my own to day. Total parts cost $1.57, but more like $4 with shipping cost. I could of made it for probably 60 cents, but I used the good stuff!
255 k-ohm 1/4w +1% Metal Film Resistors


This module will give my subs a 18db/octave roll off at 28Hz
Not really important if you subs are in a sealed box, but for subs in a ported box it's very important to have a subsonic filter close in frequency to the frequency the port is tuned to, to help prevent speaker damage.


