Coupling vs. Decoupling for Bass Response

Yes I bet the cones direct energy into that large floor and make it sing along some.
I once constructed Platforms boxes out of Medium density fibreboard.Like a big sandbox with close fitting floating lid.It helped some,would have liked more performance for the effort.The system was in large second story room.Floor was about 14x20 no center supports underneath.I placed the speakers close to outside wall where large floor is better supported.Have you dealt with middle area where floor is prone to most movement.Picturing the barn loft must have some ground floor up supports already,can strategic ones be added?Maybe more support from ground floor under speaker locations and other loose areas.A second skin of flooring in the area of speakers or even complete platform in that part of the loft.Also club stores like Sam's ,Costco have these 6x9' area rugs made of Berber scraps,edges sewn real nice.They are about $30 each,real inexpensive stain resistant.Several can damp a resonant floor as good as the sandbox did.

We think alike......some random thoughts - I would experiment with some simple dense padding such as used in workshops to keep your feet off the cement floors, its very cheap, comes in large sheets and is only about 1/2 inch thick. If it helps at all you can probably improve on the isolation by adding other dense vibration absorbent stuff in layers. Another Rube Goldberg method might be to put down the absorbent materiel, top it with a sheet of soft wood and then put cones between the speakers and the wood. This would allow speaker's vibrations to disperse some and help isolate the speakers vibrations from the floor.

I'd suggest fixing the floor, which is where the problem lies, as you said yourself.

Are a few well-placed 2x4 or 4x4 support beams too expensive?

Thanks for the suggestions so far. Tom - I only lease the space so structural renovaitons are out of the question, otherwise I'd address that. I may still ask the owners, but the other problem there is the expense. Floor area is over 1400 SF and it is one big room. There's a few quick snapshots I took of the system here where you start to get some idea of the space. There is at least 15 feet on either side of the two speakers before you get the side walls. I was thinking of solutions along the lines of what Newbee was suggesting. Perhaps as simple as a small section of carpet with pad underneath since I have some surplus from a project at home. Any thoughts on that?

Marco

I have found the loss of definition caused by the bottom of speakers placed entirely flat on either a hard of soft surface to be objectionable. To limit contact area, and stay low in budget I would think Vibrapods may be worth while. There are people who have tried or done this and reported on it, but I am not one of them.