what do you put under your sub?

id like to knwo what if anything do you put under your sub, what kind of sub, and what improvement did you notice? ty
I have two 18" infinite baffle subs which are ceiling mounted. They are in
plane with my mains. Unbelievable.
Your Sub should couple to your floor. It should not be isolated. Spikes in carpet and original feet on other surfaces.
12"X 12" landscaping pavers.
I was laying on the floor next to one of my subs while the music was playing and could feel vibrations from my janis subs. Also the cables are directed out of the bottom of my sub. A quick check of the Soundanchor website and Alberporter revealed that they have stock stands for subs and also make cutom stands.
I contacted them. Sent them the measurements for my speakers. Sometime later a set of stands arrived via UPS.
Problem solved. Carpet no longer vibrates and the sub is no longer sitting on the cables. The bass has tightend up considerably.
BTW I support and encourage DIY solutions to problems like this.
I have two solutions. Under my VSA sub in my HT room, the sub which is a downshooter sits on spikes on a 2" maple block from Mapleshade. The block rests on four (4) Isoblocks (cork and rubber also from Mapleshade) which rest on the floor. This is a suspended wood floor which is hollow underneath since there is no slab. Bass is tight and there is no boominess through the floor.

In my two channel room upstairs, the MJ Acoustics sub (also a downshooter) sits on Nordost spikes, which in turn sit on an Auralex SubDude. Check this out, Auralex developed this design for roadies to use to isolate their speaker cabinets from hollow temporary arena stages. Inexpensive and very effective - bass is tight and there is no annoying thump through downstairs.
I have ASC Subtrap under my Velodyne DD-15.
Depends on your floor (and what you're trying to achieve).
If you have a suspended wood floor, and you want to hear the sub's bass output, not the room and floor rattling, use something that isolates. The Auralex SubDude is a nice option. A cheap, but not quite as effective, alternative is $1 hockey pucks. And then there's everything from isopods to sandboxes.
If you want to hear your room rattle and feel your chair vibrate, as some ( esp home theater guys) do, then couple the sub to the floor with spikes, etc.

If your floor is concrete slab, then the effects of either won't be as pronounced, and I think most find cones appropriate here, though isolation has been said to reduce floor vibration a bit here too. Again, depends what you want.

I've tried the pucks and DH cones and Pulsar points and even Aurios under my RBH subs. They all helped in slightly different ways, but I'm using the inexpensive pucks at present. I may try the SubDude next. Then again, I like bass that's extended and tight and non-intrusive, and I also use a Tact to equalize and eliminate room nodes.

I had an audiophile friend over a while back and he thought my bass was anemic. He didn't like it. The bass was too flat. Me, I thought it sounded great, but it takes a while to get used to flat bass as we're so accustomed to the extra room-induced boom.
I have various subs throughout from M&K to B&W ASW800(matrix series), to Sunfire True Sub to Onix Rocket UFW-12. Initially, they were on orignal spikes or rubber footers. I found that with spikes anchored to their little dimpled footers over on hardwood floors, the sub tends to dance around w/ heavy bass passages and aren't fast or clean enough.

Subsequentedly, I experimented with a 6" Lovan Jazz speaker/sub stand and that was the end of all of my bass complaints. The bass notes were much more faster, bass overhand(mechanically induced) were reduced drastically and were able to blend much more seemlessly with the rest of the speaker set ups, be it stereo or HT as if the bass modules aren't there--sonocally undetectable until the presence of bass signal.

Lastly, I tried a nice Osiris stand w/ sand-filled (weighing over 75 or 80lbs) w/ my UFW-12 and it was good though more costly than the Lovan. Didn't feel like making a comparison w/ Lovan as the darn sub weights close to 140lbs. All in all, a good stand is absolutely necessary if you want clean, punching and F-A-S-T bass that starts and stops on a dime. Experiment with what works best in your application.

Good luck and have fun!

WOW! a lot of great replies..thank you all. Ive got a Rel sub connected via high output connection with speakon neutrik connector to my linn chakra amps. its a 2 channel system. Rel subs come with spike to screw into the feet, but odly enough the manual suggests Not using them. it integrates very well, sometimes seems a bit boomy/muddy. it sits about 8" from corner on carpet which is on top of slab...this is the ground floor, and no basement.

You won't need spikes....I doubt the concrete will interact much with your sub except to reflect energy...carpet and under carpet will provide damping to reduce any chance of rattle .....so why mess with it.

If it sounds muddy you may have room mode issues.....nothing to do with what your sub sits on but partly related to where it sits and the room shape itself.
My floor is a concrete slab with carpet and padding. The factory-supplied spikes for my two subwoofers were too short. They did not couple with the concrete. I was able to twist the subs a little in each direction. The subs seemed to float on the carpet.

I replaced the factory spikes with longer ones from Madisound. Nice but inexpensive cones with the proper thread size. They touch the concrete and the subs are now rock solid when I push them. Bass tightened up noticeably. Drums are more solid and defined and the bass (upright) line is better defined. Not only could my friends and I hear it but it was visible in measurements using my TacT equipment.

Later I decided to work on what was on top of my subs, frequently a forgotten area. My speakers are Apogee Mini Grands which are ribbon panels are mounted on top of dedicated subs. I put 30 pounds of sand on top of each sub and noticed improvements similar to what I observed with spikes although more subtle and not readily discernable in TacT measurements.

Before someone starts another "what kind of sand should I use thread" let me state I used AcoustiSand MKII. It is proprietary, scientifically-optimized grain size, double cryo'd, 6N silica sand. (6N=99.9999% cat crap free). It looks a lot like grit-blasting sand from Home Despot but don't be fooled. AcoustiSand really is worth the 100X mark up.

If anyone is curious they can try what I did. I had some ordinary (non-audiophile grade) sand around. I put it in double plastic trash bags just as an experiment. When I liked the results I upscaled to very heavy clear plastic bags inside of custom made fabric bags (with Velcro closures) that matched my subs. Kitty litter or bags of pet food could be tried just as a quick experiment.

One thing I noticed about the sand I used. It was very dry but it still packed into a very firm mass after being on the subs for a while. All the shaking settled it down. I can press on it with a fair amount of pressure and it will not move. I am wondering if that is still giving me good dampening or whether something that would not pack (something round) would work better. Oops, I guess this is a "what kind of sand should I use thread".

But not to forget Jaf2290's original question. Yes, I definitely recommend spikes long enough to penetrate the carpet/pad and couple with the concrete slab.
In my previous post, I made the assumption that the sub cabinet does not resonate in the frequency range you are using it for....if you have a cabinet that resonates (side walls waffle) then you have serious problems...coupling to something massive, like the concrete floor may help to dampen this but cabinet resonance means you will have distortion, especially on transients....normally a sub will be solid and very heavily braced internally to prevent this happening (i.e. no need to couple it to something solid in order to stop it resonating)
shadorne, the cabinet does not resonate at all... im fairly certain the problems i have are placement/ room effects. simply need to keep trying new locations.
Rel Stentor MK2...I put 200/pr Symposium Rollerblock Jrs under it, best tweak I have ever done. I totally lost the "one note blues", the sub opened up, easier to integrate..I used four, one under each foot. I can't begin to tell you what a huge diffence they made, and for a change, a tweak that wasn't a trillion dollars.
Auralex Gramma