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Best building material for vibration free shelving

I am building some built into the wall shelves for my VPI Classic 2 SE turntable, amp, preamp, CD player, and old Burwen TNE 7000A transient noise eliminator (that’s one for you old-timers to remember), as well as my DISH Network receiver box. The shelves must match in appearance the typical looking built-in wood bookshelves already in the room. The shelves will be located directly under my 45" wide flat screen television. They will be wide enough to hold two components side by side, other than the VPI turntable which will have the top shelve to itself due to its extra width. I will be building the shelves high and deep to allow for plenty of air circulation around the components. They will be painted.

My question is, what materials might you suggest building the shelves with to minimize vibration? If they were for books I’d normally build the sides, and top out of 3/4" birch sided plywood, the back out of 1/4 inch luan plywood, and the shelves out of oak to deal with the weight of the books without bending. I will be adding vibration damping feet under each component and am not looking for suggestions along those lines, only material and perhaps design recommendations to reduce vibration.

I was researching this last night online and on site, and saw recommendations to use four thicknesses of 3/4 inch High Density (HD) MDF, also to use granite or marble under the turntable, among other recommendations. I was wondering how birch veneered plywood would work too, as it’s ply’s, I believe, have their grains running in opposite directions. Maybe there’s some way to isolate the uprights from the horizontal shelves to reduce vibration transmission.

What would you think would work best for these built-ins. I’d appreciate any recommendations you have or your experience on this subject. Thank you for any ideas.

Mike


skyscraper

Showing 6 responses by bdp24

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bdp24
9,393 posts
 
@skyscraper---yeah, though very effective, the Townshend Audio Seismic Pods are not cheap. But Geoff Kait's isolation springs ARE. Consider trying a set.
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bdp24
9,393 posts
 
Shelves made of a material named Torlyte were all the rage in the UK in the 1980's. It's a very stiff, very low mass manufactured product specifically for hi-fi use. Russ Andrews still sells platforms and whole racks made of Torlyte, for not outrageous money.
bdp24's avatar
bdp24
9,393 posts
 
Actually, we DO know what wood Baltic Birch plywood is made from. Can you guess? ;-). It is the wood preferred by serious DIY speaker and subwoofer builders, and by a number who have made bases for their Thorens TD-124 tables (Art Dudley built his with BB). The 3/4"/19mm plywood is made of 13 very thin ply's, each ply cross-grain orientated relative to the ply on either side. Two pieces of BB with constrained layer damping between them makes a great shelf, turntable base, and/or speaker enclosure. 
bdp24's avatar
bdp24
9,393 posts
 

slaw’s point is well taken. While a stiff shelf is better than a weak one, neither provide isolation to any appreciable degree. Baltic Birch is not only stiffer than MDF, it is lower in mass, so it exhibits a higher-frequency resonance, and absorbs, stores, and releases less energy. The problem with Sorbothane-type rubber products is that they isolate down to a corner frequency of around only 10Hz, below which their isolation properties roll off, becoming a low-pass filter (very low frequencies pass right through). A turntable benefits from isolation to as low a frequency as possible---10Hz is not nearly enough.

The best turntable isolation is that provided by the electron microscope platforms made by a number of companies, but they aren’t cheap---over two grand. Roller bearings (Symposium Acoustics, Ingress Engineering, FIM) provide good lateral isolation, but couple in the vertical plane. The best lower-cost alternative I am aware of is the Townshend Audio Seismic Pod, at around $100 a piece. Put a set of those under your turntable shelf (and/or speakers, CD player, and electronics) for isolation to a pretty-low frequency---2-3Hz. Watch the Townshend video demonstration of the Pod on You Tube.

bdp24's avatar
bdp24
9,393 posts
 

@skyscraper, I use ASC (Acoustic Science Corp., maker of Tube Traps) Wall Damp as constrained layer damping. It has a "tacky" surface like double-sided carpet tape, so holds together the two pieces of wood it is installed between. It was designed by Art Noxon to be installed between double layers of sheetrock in listening rooms, as a vibration killer. It absorbs and dissipates the energy fed into it, making it a great means of constructing non-resonant shelves. I have been in a room constructed with Wall Damp between two layers of sheetrock, and the walls were VERY dead.

Another product created to provide constrained layer damping is EAR Isodamp, the blue stuff you may have seen. It's not as tacky as ASC Wall Damp, so the two pieces of wood it is placed between may need to be glued together.

I'm not sure if 13-ply Baltic Birch and MDF are equally non-resonant (I suspect MDF is), but BB is much stiffer than MDF. I put my 60 lb. turntable (with four feet) on top of two layers of 3/4" MDF, the MDF supported on two cones in front and only one in the rear. The rear of the MDF bowed under the weight!

bdp24's avatar
bdp24
9,393 posts
 
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 ;-) .
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