Marble to place speakers on?


I remember reading a thread pertaining to placing your speakers on a marble surface. Up to this point I have been unable to find this thread on the audiogon site. So I am going to ask the question again. What should the demensions of my marble be? Height, Width, Depth, and Thickness. I appreciate your time.
Ag insider logo xs@2xdsweeney33
Kevint, I have monitors and carpet and was having trouble levelling them so I bought 2 13"x13" floor tiles. I would be worried about raising your monitors too much because of the vertical position vis-a-vis your ears. I found that the sound is tighter and toeing in or out is easy. I also placed 10lb weights on the top of the monitors to kill some of the resonances. Cheers.
I had a problem in my den system with my Alon V loudspeakers. I was losing all sorts of bass between about 50-70 cycles. This gave a very "un-dynamic" (if there is such a word) presentation, and also offered the impression that the upper bass was bosted. I tried everything to solve the problem. Room placement first, then acoustic treatments including ASC Tube Traps; nothing helped. My dealer finally suggested that the bass might be getting sucked out due to the flexing of the wood floors, and thought that I might try reinforcing the flooring to help offer a more stable platform for the speakers. This was nearly impossible without major renovation, as the den is on the 2nd floor of my home. So as an alternative, the dealer suggested that I try some heavy marble slabs under the speakers. As some of you have found, not only is it hard to locate, but marble can also be quite costly to have custom cut. Now, I don't mind the expense, but only if the results justify the cost. so here is what I tried FIRST. I went to my local Home Depot and purchased to CONCRETE slabs from their outdoor garden department. The slabs measure 18" x 18" x 2" and come a few colors too! Best of all, they were only about 4 buck each! I luged them home, set them up, and viola! My MIA midbass was much improved! The midbass suckout went from being about 7db down to about 2 db down, but best of all, in actual listening, I noticed NO problem in the midbass after intalling the concrete slabs. I actualy wound up painting the slabs black and just keeping them. They might not be elegant, but for less than 10 bucks they get the job done. The only other advice I might ad is to carefully examine the slabs before you purchase them to make sure the surfaces are flat; there is great variety in the quality control of these garden products, and if the surface is not perfectly flat, the slab might not lay perfectly flat on your flooring. Oh yeah, I also covered the bottom of the slabs with felt to help protect my hardwood floors. Sorry to ramble, but I hope this helps. Regards. Robert.
Due to two little ones, my monitors are sitting alone on top of a massive oak chest made of one inch slabs of oak. Monitors are at the right height and out of traffic (stands would get knocked over at some point) but they are obviously a bit too close to the wall. So, I want to tweak them as they are very detailed under the right conditions. Appreciating all the suggestions.