Shelf Material

While I won't pretend to have an ability to attribute sonic characteristics to any of the proposed construction techniques; I will make the following comment. Anything that increases the mass that does not have a corresponding increase in stiffness (high Young’s modulus) will result in an increase in the amplitude of deflection. In simpler terms, as stiff as possible, without unnecessary mass. Kevin Halverson

High Young's modulus and low mass.... hmmm...doesn't that describe sitka spruce, universally used for piano soundboards?...and guitars, etc.? Whereas I'm tending to agree with these requirements, the additional critical requirement is that this wonder-shelf also drain or absorb energy (as heat), rather than reradiate it like a musical instrument, no? Caterham's analysis and resultant highly-evolved product seems attractive. I just spoke with a friend (Ken Parker) who is a custom luthier, and currently produces carbon-fiber covered wooden-body guitars as well. His whole life is currently wrapped up in making 3 lb ultra-stiff $3000 musical instruments that "sing" loudly even before making use of their piezo pickups. I mentioned to him all these suspension/isolation/damping options, and his initial thoughts are to try clamping the hell out a CDP by mass-loading the top and then thin-skin binding it (sorbothane sheet or 1/8" gum rubber you can buy cheap) to a 3" granite base that you can buy from machine shops (who use them as precision flat surfaces, discarding them after they get nicked or chipped).......... Yet again that old bumper sticker "Think Globally, Act Locally" comes to mind: what about damping/tuning the interior and suspension parts of CDPs and transports...y'know, getting right into the heart of it? A guy in CT (Virtual Mode) uses a Rotel 855 he damps internally as his reference CDP for the design oh his well-respected passive attenuators!...claims most CDP problems are mechanical, not DAC related. I'm tempted to send him my 855 for tweaking before replacing it with a Bel Canto DAC/DVD setup, etc. Yet Caterham speaks of not upsetting the original voicing of a product by such internal damping in lieu of vetting its vibrations through his shelf, which, with additional hard cones, further isolates the component from externally-generated vibratory spuriae, as well. Christ, I don't really know where to start here...still using that 5 buck wheel barrow inner tube from Home Depot! Redkiwi--the deal with maple butcherblock is that the individual strips of wood are glued together in opposing-grain arrays to provide mechanical integrity--no warping, and controlled expansion/contraction. I suppose it won't ring like spruce, of course, but don't see why it would be better than cheap MDF in this regard. It's VERY hard, and will require carbide tools to cut, dulling them readily because of the glue in the joints, as well. It's beautiful and lasts forever, though, so you'll get furniture-grade shelves as a bonus...... Anyone familiar with Virtual Mode's $200 CDP mods? Thanks for these thoughtful and educational posts, guys. Ernie

As for Subaruguru's comment about the sitka spruce, if it does have a high Young's modulus, then it would be an excellent "shelf material". My original comment applied only to the selection of the shelf, as the title of this thread states. Once a shelf has been chosen, then a suspension system can be applied to decouple the component / shelf from the structure which it resides upon. The goal of the shelf should be to rigidly couple the energy from / to the equipment into the suspension system. The lower the mass (for the combination of the shelf and product), the lower the amplitude (and higher the frequency of the resonant system) assuming that the compliance remains constant. Another concept to consider is the "Q" of the suspension and the use of any damping (lossy) properties. A good field of study would be to take a look at what turntable manufacturers are doing. They have had to deal with suspension / decoupling systems and have a wealth of practical experience. Kevin Halverson

It seems to me that MDF would make a very good shelf material - low mass and high rigitidy. I use 3/4" instead of 1/2" with good results as a standard (non-suspended) platform. It also has no grain. Am I thinking correctly? I have a 5' x 2 1/2' x 2 1/2" maple glue-lam butcher block that I salvaged from a restaurant but would rather go with MDF based on the info in these posts.

What about carbon or carbon fiber?