Floor Resonance and Full Range Speaker Stands

If there is any way to bolster the floor with some additional lumber & floor jacks underneath the speaker locations, I believe that would provide a better solution than basic speaker stands which likely will couple additional energy into the floor perhaps shaking it even moreso?

I isolated my Dunlavy SC-Vs from the regular joists and then supported that section of floor to the concrete below. This was a huge improvement, easily measured with a real time analyzer. Floor jacks are a cheap experiment

Supporting the floor from below is the best way to go, but if it's on the second floor or some location where that is impossible there is an alternative. Get large slabs of granite. The bigger the better. These will not move much, and will distribute the energy to a large enough area that it will not cause the floor to vibrate as much. You could even try to put some sort of absorber between the granite and the floor (such as a dense piece of carpet), but due to the weight of the granite that might not help much. As to where to get granite--well you can go to the kitchen counter place, but that's going to probably be pretty expensive. It's better to try the guy that makes tombstones and mispelled someone's name one day--that piece of granite will be pretty cheap.

Thanks for all of the responses. I live in an apartment in NYC so I guess suporting the floor is out unless my down stairs neighbor wouldn't mind the construction work. I was about to purchase a pair of Lovan full speaker stands and although I thought it would help a little, I would've been surprised if it remedied the problem all together. I have concrete slabs in the basement of my building that I was planning to use but never did. Any reason I couldn't use concrete slabs instead of granite?

The concrete slabs should work fine--and it sounds like the price is right. Granite is probably a little better because it's a denser material--but I don't think it would be much better. Give the concrete a try--and let us know how it works out.

If your speakers are spiked, you could try putting a set of Aurios Pros (the larger, self-balancing Aurios) under each speaker. They do an astounding job of floating the speaker so it doesn't feed vibrations to the floor or interact with vibrations from other sources. A set of four will support between 800 and 1000 pounds. A set of 8 (4 per spiked speaker) will set you back $1600, but it's the best $1600 I ever spent, and I also live in a New York apartment. Audionut.com carries the Pros.

I'm also in NYC and, in the process of moving, looking to bother the new neighbors as little as possible (just think, could be coming to a building near you...). For the past two years, I've had no downstairs neighbors, thrown the Thiels on spikes, and let'em rip without consequence. Now, I'd like to decouple the speakers from the floor as much as possible (to transfer as little sound as possible downstairs). Is granite blocks the best way to do this? In spare moments, I'd dreampt up all sorts of theoretical, layered isolation configurations and such, but am only guessing. If we're talking granit (or some similar, rock-like stuff) how much of a slab would one need to do the trick? HxWxD, approximately? The more the better? Finally, since I'm playing 20 questions, where would one find a slab of granite? I'm not talking designer acroutrements, just the basic hunk of rock variety. Thanks.

Set the granite on some inflated bicycle inner tubes and set the speakers on them.

Concrete slabs may "ring" while granite can absorb -- so probably better. I beleive the best solution would be to use granite sized slightly larger than your speakers, and decouple the granite from the floor with the likes of Audiopros or even cheaper devices such as Nordost's Pulsar Points.

Good luck!