Granite under your amp???

I have had speakers with the option for granite bases, has anyone used a slab of granite under their amp, even while on a good stereo rack? If so, any changes?
It's probably not really something you want on a rack, the granite will weigh upwards of 200+ pounds. Difference in sound = slight at best. Looks very cool. The best/cheapest way to get a nice one of these is to buy what's called a Machinist's surface plate from one of the online tool vendors. For about $50 you can have a 2-3" thick, polished slab in 12x18 or 18x24" size, slightly more for the larger one. As a bonus, it's a precision flat surface within very close tolerances, so if you need to true up some straightedges or something you are all set. ;-) I've thought of getting a couple, but they are mostly just eyecandy, and at 250lbs, heavy to move around.

I was thinking more like 1" thick. Dimenesions would be no bigger than 17 1/2 x 19 1/2, I can't imagine this coming anywhere near 200 lbs.
A piece that size in 1 1/4" thickness weighs 36lb. I use them for shelves in a sand filled Lovan Sovereign and they work very well.

Please keep in mind that granite does not have very good tensile strength and needs to be supported by something that has the ability to carry the weight and not bend. I was carrying a piece the other day by the edge and half of it just broke off and fell. Consider what would have happened if it was being used to support an amp. Ouch!
Does somewhere like Home Depot carry these? How much would I expect to pay?

What exactly does it perform? (Reducing vibration...?)

As for support, I would place it on one of my shelves on my Sanus stand.
Surface plates (the cheap ones I mentioned) dont' come as thin as 1", 2-3" is the norm. Shipping weight on the 18x24x3 is 200-250lbs IIRC. 17x19 (weird size, btw...not going to find something like that off the shelf) x 1 is still going to be 50+ lbs., at least. It's tough to estimate the density of stone until you work with it in person. For the surface plates I mentioned, $45-135.
Anybody tried this one?

I bought a piece of scrap granite from the neighborhood tomb stone guy.It is ~16"x18"x2" 50-60lbs.Shiny smooth on one side,dull smooth on the other.I paid $20, wiped the bird doo off it and painted it black.
I have a diy amp stand under the granite.In between the stand and granite is a very thin sheet of foam like material I picked up at a hobby shop.
My Pass Labs Aleph-3 sits on the granite.I still have the stock Pass footers under the 3.They are pretty good for stock.
Since using the granite the bass is tighter and a bit deeper.Focus is a tad better too.No doubt worth the money and effort.
So Dave when you go over the falls is the granite gonna be going with you, I know the record collection is :) let me know when your gonna go for it, I'll shoot out there and if you make it we'll do diner. I have also been contemplating getting marble/granite/any cool looking smooth rock surface and getting rid of the aluminum I have been using. I have been using 1/4" thick T-6061 aluminum sheets for shelves for my audio gear, does anyone know if there will be any improvements going to granite/marble/etc?

T-6061 aluminum air hardens. By this time that amp stand must be like a trampoline-very lively. Not exactly what you may be looking for.

Granite (Harbor Freight has the machine plates on sale from time to time-free shipping also) is harder and more lively than marble. Granite is also a bear to work with without diamond tools.

18x18 inch marble tiles are usually available from a tile/carpet store. If you buy close-outs and partial boxes you can get it real cheap. 18x18 x 3/8 thick #3.00 USD per tile and free cutting to size if you ask nice (on a store wet saw a piece of cake). Again, marble has a low shear strength so it needs full support underneath at least on the amp contact points.
What Killerpiglet mentioned sounds interesting, it's very inexpensive.
I had an extra slab of 1" granite laying around from my kitchen so I did a little experiment... I placed it on top of my turntable stand with 4 Michell Engineering cones underneath it... and then my Gyro Dec on top... and it was the cheapest improvement in sound quality I have made in a long time...
Tim-When I had my audio crisis a couple of days ago I was considering taking a ride over the falls.David+99
I was able to get a couple of 15x24x1 polished scraps of marble from a local tile and counter shop for my amps. They had a pile of scraps from jobs and let me have them for free. All I had to do was clean them up.
OK, different audiophiles say that a hard surface, like granite under the amp makes it sound better and other audiophiles say that if you isolate it on a air suspension device that it sounds better. So, which is it? And how could both be better with such different approaches?
I think that there can be MAJOR differences with various tweaks such as those that are weight, isolation, coupling, damping, etc... based depending on the type of flooring that one is on. Someone on a hard concrete slab will have VERY different results using the same tweaks as someone with their gear on a suspended floor i.e. over a basement or crawlspace. The results from one suspended floor to another suspended floor will even vary as they may have different levels of support / flexing taking place. Sean
I use granite under my speakers primarily to protect the hardwood floor. Results have be outstanding.

For what it's worth, I think granite would serve as a better base than marble - if you look closely at a slab of marble, in most cases it's held together with some kind of fabric. Marble is full of fissures and the cloth stuff keeps it from falling apart!!

If you are looking for something that is structurally sound, go with granite over marble - however the really pretty granite with buzillions of colors can be almost as fragile as marble. The "absolute black" granite seemed to be the strongest.
I just built a custom audio rack that uses granite shelves. They are 3/4-inch thick pieces that were custom cut by a local stone company using their computer numerical controlled water jet machine. The shelves cost $100 each (five total) and are 19-inches wide by 26-inches long with a curved front.

Perhaps if you look in your Yellow Pages under "stone" you can find a like business in your area. The people I work with also have "drops" which are scrap to them that they sell really cheap. I buy the drops and make tables with them - average cost for a 30 x 30 inch piece is about $15. I use a dry diamond blade in a standard circular saw to cut them.

With any stone, you need to look carefully to see whether there are cracks in it. I got one piece of scrap that had to be fixed because of a crack so that it would not break. This is not difficult to do. You can use a marine epoxy - not automotive (like Bondo brand). Auto epoxy is polyester based and too thick.

You turn the rock over to expose the back side and apply the epoxy along the the crack with a brush feeding it into the crack. The epoxy will work its way through the crack and come out on the front side (place the rock on a piece of wax paper or you will glue it to the surface it is sitting on).

Wait overnight, turn the rock over and scrape the epoxy off the front side. This is easy to do if rock is polished. The piece I fixed has been used as a table top and used outdoors on a patio for the past 4 years. The epoxy I used was MAS brand, it's like West Systems or System 3. You can also get small cans of "marine" epoxy at Home Depot.
I bought a marble cutting board (or bread board)at a cooking retail store for $20.00. I put it under the cd player I was using, and it sounded much better.
here's what i did for my paradigm studio 60's. went to home depot and bought two 18x18x2 concrete squares and they had some rubber mats(4 to a package) that fit together for kids to play on and two 18x18 ceramic tile sheets. i cut four 18x18 squares from the mats used contact cement and glued one on each surface of the concrete blocks then i glued the ceramic tile on each rubber surface paint the sides of the concrete square and you have a great stand.
cost?? concrete $4 each, rubber squares $15 package of four, ceramic tile $4 each, contact cement $4 can, spray paint $4 can total = $40 talk about heavy and they look great, bass is tighter and there is a lot more air around the instruments.
according to Mapleshade records they have tested all possible platforms over the years and found maple (go figure) buthcher blocks to be the best, even over 100+lb slabs of marble and lead, I haven't done the experimenting to confirm this
Hi Brianmgrar,Under Tech Talk there is a lot of good information on threads-Isolation vs. Absorbtion and Shelf Marerial.

Under Misc. Audio look for the thread-Amps Stands-Do They Work.

There was one called Footers/Shelf Material. Try doing a search.
thick 24inch x 24inch on a side with beveled edges. cost abt 500 bucks for 2 (edges were expensive) they weighg abt 50 lbs+ each. But my ml requests now have a nice base that keeps the spikes from going through the floor.
Gtejr, you simply set your spikes on the granite? If so, isn't it easy to slide them around on the granite?

Did you notice any change with these bases?
Brianmgrarcom, I too set my speakers w/spikes on granite. Believe it or not, it's not that easy to slide a spiked speaker on the granite. The spikes dig in and if your speakers are heavy enough, will scratch the granite.

My granite sits on hardwood floors - I have three small felt pads under the granite which allow me to position the speakers/granite with ease.
I too have wood floors, I use skeets under my spikes, made by Linn.
pads to protect the wood floor. The spikes are in direct contact with the granite. I removed the two front outside spikes (only use 3) that way they are all load bearing and they are all making full contact. (also it is easier to adjust the tilt (front to back) to match my seating position. No vibrations what so ever.