I recently purchased a type x 12" sub and i'm experiencing a fluttering coming from the sub on low hits of bass. The subs wired at 2 ohms to a pdx 1.1000, and i have it in a sealed box i built (not the first box i've built either) with the sub mounted magnet out. There doesn't seem to be any air leaks, i've looked into that, and the sub plays fine in most situations (roughly 95% of songs i've tested sound great). An example of a song that i'm experiencing this would be something like eminem - sing for the moment (problem occurs in the corus)

The box is 0.9^3 ft. (including 3/4" MDF, and mount displacement)

Any ideas?

 

Bigger box. This will help with the lower notes

 

is it volume dependant? does it misbehave at mid volume and worse frequency wise at higher volumes?

have you watched it or just heard it, could something else be making a sympathetic sound in response to the note? could your amp be running out of juice?

It probably is box size (volume) as ridinspinners said but it could be something else.

 

i'm planning on building a box with the sub mounted normally (magnet down) to replace this box any ways. The box was to be temporary but it was in the mids of alpines suggested range so i thought it shouldnt be a problem. Guess imma just have to build a new box and see the results, amps tuned fine and doubt its out of juice. New box is expected to be larger and sealed