Total bass suck out at 40hz

I do have them set up symmetrically I will try that first. I was thinking the swarm is the way to go. Just not sure how to implement more subs with long cable runs. Is 30' of single ended cable on a sub a bad thing? Random is better, this is what I am getting mostly.
Symmetry is death for bass. All symmetry does is ensure even more modes and suckouts. What you want is asymmetry, so the modes are all different frequencies and locations. More subs helps even more with this. More subs also means each one has to put out less total volume, because they all add together. This further smooths out response.

Long runs are no problem at all. Wire quality is much less important with subs. We just aren't that sensitive to fine differences in low bass the way we are with midrange and treble. Biggest problem guys have is getting their minds around just how different low bass is and how important it is to treat it completely differently than everything else. 

My DBA is four subs driven by 2 Dayton amps, and a 5th powered Talon Roc sub. You can easily hook them up in a chain one to the next around the room. https://systems.audiogon.com/systems/8367#&gid=1&pid=10 My one pre-out goes to the Daytons, then from one Dayton to the Talon Roc. You could go from pre amp to sub to sub, etc around the room. 

Start with one near each corner facing the wall, with each one a different distance from each corner. Its so simple when you do it you will be shocked that there's so few telling you about this. Its totally the way to go. Everyone knows it. They just won't admit it. 

At a speed of sound of ca 330m/sec, a 40 Hz wave length estimates at ca. 8.3 m, half wave = 4.15 m, pretty close to 14 feet.
I.e., you experience a text book suck out (cancellation of half wave by reflected half wave of opposite amplitude).
As others have stated, move the subs around, asymmetrically.
Good luck!

I have audible base to below 30 hz, just none at 40. My room is long and narrow, equipment is set up on narrow wall. 14' x 38'.

@mizike   The phenomena you are dealing with is called a Standing Wave. When the bass comes out of your speakers, before you can even hear it (the ear can't hear anything until the entire waveform has passed by it), its bounced off of the wall behind you and your listening chair is positioned such that its out of phase with the incoming waveform at 40Hz.


You can do room treatment and also electronic room correction using some really sophisticated software, but you won't have much impact on the standing wave.


What room correction does is actively figure out how the room deviates from flat and equalizes it. the problem is no matter how much power you put out at 40Hz it will get cancelled, so room correction won't work.


Room treatment is the idea of installing bass traps to prevent the energy bouncing around. The problem here is that as the bass notes change, the places where the incoming and reflected wave energies combine and re-enforce (rather than cancel) changes, so unless your bass traps can move around dynamically with the music, this won't work either.

But running multiple subs does (this is the distributed bass array you've been hearing about on this thread). By running multiple subs you are able to break up the standing waves, and thus have even bass throughout the room.


People on this thread have been talking about nodes, nulls and modes- these are references to the behavior of standing waves. I'm only putting this post up so you know how these terms relate to what you are experiencing. Good Luck!

Thanks for your input, greatly appreciated. I am running two subs, seams like more is the next step.

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.