Total bass suck out at 40hz

Ok, time for an update. First off I spent some time moving the two subs I had around. I finally got some bass output at 40hz but it was 12-13 db down from the rest of the band. I ordered some Y cables from Blue Jean and they came today. I have a big ass HSU 15" sub for HT use that I moved to the far end of my long room. I put it in the corner, 4" from the side wall and 10" from the back wall facing into the back wall.(by back wall I mean behind my chair 24', very long room). Holly smokes Batman, who would have thought that it would be so absolutely awesome. I don't know why it works but it dang sure does. I have full artriculate base output from 20hz up through 60hz. I have all the crossovers set @ 55hz. The volume went WAY down on the two Rythmik subs the HSU matches them at approximately 1/3 volume. It's so good I can't believe a forth subs will make it better.(I'm getting one anyway just to be sure) I forgot to say one "front" sub I placed on a extra heavy duty steel & wood table 34" off the floor straight behind the left speaker facing into the left corner about 2.5 feet out. Could not be any happier with the results.Thanks again to everyone that gave tips and tricks and real advise, sincerely, Allen.

who would have thought that it would be so absolutely awesome. I don't know why it works but it dang sure does.

Actually the explanation for why is posted above. And also explains why the 4th will help too- but beyond that is a vastly diminishing return. Glad you're getting it sorted out!

Yes sir, I actually know why it works, I was being a wee bit facetious, thanks for you thoughts.(Giddy with delight)

try putting the subs on the wall behind your listening position and have them fire looking towards the fronts. Reverse the polarty on them and you will get a smoother response than you now are getting.

Could one of the speaker cables be reversed?