Best building material for vibration free shelving

@n80, not a good idea to use the preamp’s rubber feet coupling into a hardwood footer. You can’t rely on the stock rubber feet to provide any isolation; also, rubber will colour the sound and the feet are not secure since they are either glued or screwed into the preamp chassis.
For transparent isolation, footers should sit under the component itself. This way any vibration will travel from the underside of the chassis to the footer. There are two methods of isolating a component, either drain vibration to a platform or plinth, or decouple the component from the shelf.

There are many threads on this subject in the archives. Geoffkait has provided very good advice regarding acoustic isolation.

Your walnut footers look like a good design for draining vibration and also for isolating acoustic/ mechanical vibration from the shelf. What you are missing is a set of cones where the flat end sits under the preamp and the point sits in the dimple of the walnut footer.

@williewonka, have you compared your wood cones with Myrtle wood blocks? I'm using the blocks under my tube amp and find that the image is not well focused perhaps due to vibration.

I like the idea of using wooden cones rather than blocks. I also found these cones...
http://www.russandrews.com/us/system-racks-supports-equipment-feet/
These are made of oak, the Glasshouse are beech. Any thoughts if using cones would be superior to the Cardas Myrtle wood?

I've said it before, and I'll say it again. 3/4"-19mm 13-ply Baltic Birch is really stiff, and fairly non-resonant, much more so than Maple. Two pieces of it with a thin sheet of constrained layer damping between them makes for an excellent shelf. Maple may be liked for it's "pleasing sonority", but who wants that? Apparently a lot of people ;-) .

lowrider, to be honest, I made those because I was bored and bought the sorbothane on a whim. I can hear absolutely no difference in SQ from when the line stage sits right on the rack, right on the sorbothane or in the configuration I described above. I suppose I just don't have the ear for it.

But one has to wonder why a company like Audio Research would put crappy feet on an otherwise high end and fairly uncompromising piece of audio equipment. And for all I know, they are not rubber. They are also more or less cone shaped. So the contact point with the wooden blocks is actually very small

So here's my somewhat facetious take on my setup:

Special cone shaped vibration damping feet on the pre amp fit into a custom designed dish shaped concavity within the American walnut isolation blocks (English walnut will not do) whose grain orientation, aging and density limit sonic vibration transmission. These blocks sit on sorbothane pads which isolate the system as a whole. These sit on a spiked audio rack with thick MDF shelving. Considerable effort was expended tuning this components for that perfect sonic quality. ;-)

Bdp24, what are you using for the "constrained liner damping"? Also How are you connecting the two pieces of 13 ply Baltic birch together, or are you simply setting one on top of the other withe the damping material in between? I read somewhere where one person glued damping material on either side to two separate boards as you describe. Are you setting the shelf on clips, like a typical adjustable shelf like George described above or are you connecting the shelves to the vertical uprights? Do you feel the 13 ply would be less resonant than HD MDF. Sorry for so many questions but I think you’ve put forth some good ideas here.

N80, agree with you that MDF would sag spanning 40 inches. I figured on bracing the shelves with an upright in the center, probably have to do the same with Baltic Birch plywood too. I’ll look on Amazon, and also price, sorbothane as you suggest. I was hoping one of the big box stores like Lowes or Home Depot might carry it.

Stereo5, dill, and schubert4, thank you for the suggestion on using maple.

Czaeivey, I like you idea for using sheetrock squares. They likely wouldn’t vibrate, but also would likely collapse under the weight of heavy components like the amp, unless you are laying the sheetrock on another shelf material. I’ve lots of scraps of sheetrock laying around.

Steve (Williewonka), After reading your suggestion, I might try using my piece of leftover marble, and set it on the top shelf under the turntable with a piece of tool drawer liner, or constrained layer damping in between, once I figure out what that is and how to get it., Thanks for your ideas.

Thanks all for you input and suggestions. I'll be incorporating several of them. I’ve learned some new things already too, Never heard of using sorbothane, or of constrained layer damping before.

Also, and I’m repeating myself, if anyone knows which is less resonant between High Density MDF and 13 ply Baltic Birch, I’d very much like to know.

Mike.