Sandbox Design Advice

thanks dga. appreciate the input.

https://systems.audiogon.com/systems/8367

Both the top and bottom shelves of The Solution turntable stand are sand boxes. There is no right or wrong way of doing it. Some features are in general better than others however. Kiln dried for example is going the wrong way. That's nothing but trouble for no benefit whatsoever. In fact it is the opposite- wetted with a small amount of mineral oil is much better. Its better in terms of vibration control, and way better in terms of neatness and dust control. This rack has been up and running more than 15 years with nary a stray grain. Try that with kiln dried.

The concept you will find most useful is understanding there is no such thing as isolation. That is not what we are doing. Its vibration control. The main source of vibration we need to control is the component itself. This is the case regardless of what component we are talking about. 

That's why this rack works so well. Read the system comments. Every single bit and detail in the system contributes to the fantastic performance achieved. Wish you could hear it. You would be amazed. Seriously. Again, read the comments. The rack is as important in achieving this as anything else. 

Compact sand with just enough mineral oil to eliminate dust and help it keep its shape, that is all you need. An inch or three, anywhere in there is fine. The container in this case is concrete because a lot of mass helps. It simply takes a lot more physical energy to move a large mass than a small one. So the more mass the better. But solid concrete or granite, while massive, have the problem of ringing. Hit an undamped block of either one you will hear the ringing. This same ringing is imparted back into the component.

This isn't theory. This isn't parroting, regurgitating, repeating nonsense heard elsewhere. This is actual trial and error experience. Don't take my word for it. Get some material, cut some pieces, try it yourself and see.

Been there. Done that.

How I know.

Same goes for the shelf on top. 

Hard to tell from the pictures but if you look real close at #7 you will notice the smooth packed sand in the bottom shelf with pieces of plain old MDF sitting on the sand, BDR Round Things and Cones resting on the MDF. 

Vibration control in action. The Herron generates vibrations, BDR controls them, MDF and sand stop and absorb or dissipate that energy so it doesn't reflect back up into the Herron. Just what you want. Without the sand, if it was directly on the concrete, the sound would be more dynamic and immediate but with an unpleasant treble emphasis owing to the concrete ringing.

There are of course better materials and better solutions, just none anywhere near as cost effective as this.

If you want to do concrete like this its a bargain, all the concrete to build this rack was under $10. The most time consuming part is designing and building the molds. But one mold for three shelves, pretty good deal.

The other big thing to keep in mind, other than isolation being nonsense, is that because the problem is vibration control then the details of each particular situation are important. The optimal solution for a rack like mine on a wood beam floor is slightly different than a concrete floor which is slightly different than putting a sand box on top of an existing cabinet. In always pays to look carefully at the site, its various material properties (metal or wood, floor or wall mounted, etc) as well as physical considerations. On the floor is best, and the higher it must be the harder the job becomes. 

Anyone tries to tell you "just do X" is leading you down the primrose path. The best thing you can do before building anything is try a few proof of concept trials. Its not necessary to build the whole thing in one fell swoop. In fact that is about the worst way. What everyone does, of course. But if you build a few test pieces, it can be as simple as cutting some 3x3 squares of MDF, acrylic, wood, putting them under your footers, see how they sound. Take a couple small containers, pack a cup of sand in, put the test materials on top. This is incremental conservative high success rate way to go about it. 

I like dgarretson angle iron/aluminum idea a lot.

FWIW, the very first DIY project for audio I made was a sandbox for an my VPI HW-19. Never had any problem with construction out of MDF. Used glue @ screws. I later on used that same s-box for a 100lb amp.