I have a FF3 as part of a SS3-based 7.1 surround setup. I find that for movies with lots of LFE, I get a fair bit of rattle, and much of it seems to come from the sub itself. I have it on the rubber mounts, on a ceramic floor. I calibrated the system some time ago. The sub volume is set to barely above zero!

What I did do was remove the grille, and put some padding below the cables coming out of the back, and that did make an improvement, but it still rattles.

Any suggestions?

Bummer - shouldn't make a peep. Sounds like an air leak. You should return the sub to the dealer for inspection/service.

Same issue with me, with a force field 4, concrete room with ceramic tiles. I folded up a yoga mat to place the sub on to see if it was resonating/vibrating too much due to the concrete, it helped but it still occurred with the mat.

Dealer took it back, but was unable to replicate the sound in their demo room, so they're bringing it back to me, and we'll see how it goes.

Mod - Would a concrete room in your opinion cause the sub to be more susceptible to this type of rattling? It's definitely not a constant sound and only happens at certain times/frequencies, and this is with the sub volume at around 9 O'clock.


Edit (addition) - I just had the sub back, and we managed to replicate the rattling at certain frequencies (particularly in Dark Knight rises, in the beginning when Batman is just about to jump down the spiraled multi storey carpark onto a van, the scene with Batman impersonators and criminals). Now with someone sitting on the sub, the rattling practically disappears, so I am hypothesizing that it's possible that with concrete/tiled floors, the feet of the sub and it's weight, may not be substantial enough to prevent the sub from vibrating and rattling at certain frequencies? I plan to next buy a rug to see if this helps alleviate the problem. Hope this may help the OP as well.

Sorry for the delay - tried to get engineering to duplicate the issue and report back. So far they have been unable to duplicate the issue in the lab.

Would someone sitting on a sub with an air leak eliminate/reduce the rattling?

LOL... I wouldn't think so, unless the air leak was under their butt maybe.

I can only guess that the pressure being created by the passive radiator's slot loading to the floor, at some output and frequency, is causing an air turbulence rattle. If there's nothing loose inside and no air leaks, there's really nothing left to consider. Did you try the rug?