[hotroady]

 I noticed while modding my speakers, that anything I could do to tame cabinet resonace, lessened the tendancy of things vibrating in sympathy in the room. The number one offender, turns out to be the 'HT sub'.                  The HT crowd seems to believe they are not getting their moneys' worth, if the room if not shaken, properly.                                                         Not good for music! Not installing damping material, or cross bracing and leaving them on the floor, worked out nice profits, for lots of company's...some of these will dance across a wooden floor, by themselves.   The free part, and real effective...raise and isolate from the floor! Room resonance? Where? Most all of it comes from cabinet resonance. Feel your speakers, and vibration. Take a look inside..minimal fiber stuffing, with a ported speaker? Multi layer accoustic foam is miles better. Thick single layer foam works well for subs, as not as many frequencies to contend with. The port it self may need to be supported with a cross brace, that could also be used to tie two sub walls; together.                                                         Woofers are dipoles that send waves 180 degrees out of phase, while sending music waves out the front. You want that port to disperse it..not the cabinet.                                                                                               Most paper cones do a pretty poor job of blocking that out of phase, coming out the front. Heavier alumized cones with thick rubberized surround, is better than paper and that airy foam varity.                                                       I put my sub on the steel TV rack about three inches of the floor. More line source to the ear and less absorption by the carpet. Down fire sub? Try a thick 3/8 inch glass plate  sourced from from local glass cutter left overs. My cost 5 bucks for the glass and 5 bucks to cut it to an exact fit. They were glad to see it go.

[Listens2tubes]

Why put a piece of 3/8" glass inder a downfiring subwoofer. Sourcing 3/8" - 3/4" glass from glass shops in my area is priced on a 3 sq.ft. minimum from a price chart supplied by the distributor. To get a piece that cheap the shop must specialize in auto glass od stor fronts and the owner aws given some heavy glass and usually has no call for it to let it go for 5 bucks.

[hotroady]

These were pieces that were odd left overs. One piece served as a glass top, the other below the sub. Really smoothed out a down firing 10in Klipsch. Seems counter intuitive, but worked well, ymmv. Main idea is to isolate sub from floor. Firing into carpet absorbs power, firing into wooden floor amplifies rumble effect. Cement or tile floors can be too live, also. I just suggested glass as something to try, based on my experience. Front or rear firing sub results are predictable. What's good for HT effect, isn't good for music listening.

[BobM]

I would suggest raising a sub off the floor a foot or more, if you can. Taking away all boundary reinforcements (contrary to most people's putting a sub in a corner) will tighten up the bass dramatically. Yes, you may need to turn it up a bit, but it will be tighter and less boomy.

For downfiring subs this change can be easily done by just turning it upside down, so it is now firing upward, and putting a board (or your glass) on the now upfacing feet and placing something heavy on the board/glass to hold it down.

Experiment a bit and you may find it works better for you.

Enjoy,
Bob

[hotroady]

I would suggest raising a sub off the floor a foot or more, if you can. Taking away all boundary reinforcements (contrary to most people's putting a sub in a corner) will tighten up the bass dramatically. Yes, you may need to turn it up a bit, but it will be tighter and less boomy.

For downfiring subs this change can be easily done by just turning it upside down, so it is now firing upward, and putting a board (or your glass) on the now upfacing feet and placing something heavy on the board/glass to hold it down.

Experiment a bit and you may find it works better for you.

Enjoy,
Bob

                                                                                             Thanks Bob..that's what I'm getting at, experiment. I raised my little Claritys another 4in, for a total of 5in. Raises the soundstage up, so the vertical sweet spot is pretty much the same, seated or standing.