Down-firing Sub makes floor rattle

There's alot of great feedback above from everyone.

As an additional option, you might wish to consider grabbing a single Adona AV45AS amp stand; they work amazingly well as a subwoofer isolation and elevation platform. Depending upon whether you buy 6", 12" or 18" uprights (legs) and where you lock the x-frame into the uprights, you have a large degree of control over the separation of the sub and it's down-firing port from the floor.

The port then would be firing at a granite surfaced platform which would allow the wave to have minimal interference as it travels out of the port and then the many feet out in your room where sub-bass waves actually begin to materialize.

I have my REL Britannia B1 on an AV45AS with amazingly clear results (IMHO). Send me an email privately and I can share pics and other info with you if you like. Paul at Adona is also a great guy to deal with and has a vast degree of knowledge that he loves to share.

Check out http://www.adonacorporation.com/av45as.html

At $300 US their reasonably priced, look great and deliver real sonic benefit; I use them throughout my system. They're also modular so you can start small and over time, if you like, grow your setup.

Room vibrations, that I understand, as in interacting with room acoustics. Floor vibration - that's a different story, it seems. Decoupling, proper placement etc, I am sure, could help to minimize the effect of the down-firing sub rattle. Personally, I've never had good luck with those, in real life environments. Floor, furniture...everything tends to vibrate more with down-firing subs,that's in addition to the usually less musical, overbearing bass quality. IMO, of course

hey, thanks for the info....i am getting very close to getting this sub sounding very, very good with pretty much seamless integration......i have been playing with the phase, which i just thought should be at 0 because the sub is in line between the speakers...while it gives me the most bass, it is not the best bass...i think this has been most of the problem i have been having....i have neen trying 90 and 180......180 degrees seems to be the ticket...all of the problems i have been having are mostly gone....i am now getting good tight, deep, bass, with no overhang...

zephyr, i do like those stands and may look into it

I had the same arrangement with my mains and sub alignment and began at 0 degrees phase. After much testing and test relocating of the sub, I found the original position was the best (to remove a room mode or two) with 180 degrees yielding the best, most musical and appealing bass...My REL B1 is front-firing however it does have a floor-firing port.