what is the theory behind maple stands and racks?

You know its fishing season here in Oregon and even tho its a slow year there's lots of out of work people trying to catch dinner. Well, I went to the local fishermans supply store with the same notion in mind until I came across a bunch of lead weights in the shape of doughnuts called sand dollars. They ranged from 4 to 10 ounces. Naturally my mindset shifted to the potential of for these toxic beautys as audio vibration isolators, so I scooped up 8 of the 6oz weights and some 1.5" cork bobbers and forgot all about fishing.
Back home I went to waste another weekend with obsessive experiments. The guilt soon vanished as I found audio nirvana in a funky configuration that was insightful about vibrations both coming and going from my system. It may be germaine to this discussion.

My Primaluna CD player rests atop 2 inches of maple plywood and mdf. It sounds great but gets little use since hddtv dvr and plasma caught my eyes.
Anyway, If your not familiar with it, the primaluna8 is a tube hybrid cd player with a nice heavy chassis and some beefy rubber feet. I recently swapped the power chord out with a CCAC silver one and rolled the tubes for the first time to some NOS ones that came with it but I had never tried,the improvments were beguiling and compelled me to see what else I was missing out on..
So I started balancing the player on various things. I tryed the dali speaker spikes and their bases. It was an improvement, but the biggest improvement came when I balanced the player on 1.5" smashballs resting on the lead dougnuts. The players big rubber feet have a cavity in the center that somewhat fit the smashballs. The smashballs are quite squishy or resiliant, and so reduced to 1" in height. and the lead sat atop the maple. The lead seemed to act as a heet sink and the air cushion of the ball under stress seemed to insulate the player from ground vibrations coming the other direction.
So long story long, I think you a right, mass matters.
What was cool about this setup was it is a very delicate balancing act and one can see the effects of vibration by simply walking up to the player, the balls would start to roll off balanc.
By the same token the vibrations coming from the player could also move the balls out of alignment. eg I got the balls perfectly aligned under the feet and in the lead doughnuts, turned it on and sat down to listen, After a time the balls would move. I know they are under constant pressure to push back just from being squashed, but the they moved more when a cd was playing.

Bottom line is the improvements were huge with an air cushion separating sources of vibration and the density of the lead as an asorber was astoundingly better than just the balls on the maple itself.

Stevenball,

Your example of the vibrational consequences of a poorly hit ball is quite graphic, but if efficient transfer of vibration is the only story wrt audio platforms, then I think wood would not be the material of choice. There are much stiffer materials available that would pass all the vibration through to whatever your block is sitting on. Unfortunately, they would also pass ALL the room vibration imparted to the rack-footer-platform "system" back to your electronics gear. So if maple absolutely "does not absorb vibration" as you suggest, that would not necessarily be a good thing for your hifi. Fortunately, for musicians, music lovers and audiophiles everywhere, this is not the case.

Maple is very dense and very hard for a wood, but in applications for musical instruments and audio equipment platforms it displays complex behaviors. It functions to dampen some of the vibrations, transfer others, and under certain conditions, it can actually amplify or increase the resonance of certain frequencies. The tendency to accentuate certain frequencies may have positive or negative effects on overall sound in hifi applications.

From the Imigi Audio Products webpage:

"...The benefits of solid-maple as a component platform have been known for many years. The sonic properties are unique. In addition to the natural damping properties of maple, when the platform is properly designed, it has a unique ability to allow upper harmonic overtones to fully develop. This is often apparent in the way you can hear a bow drawn across a violin string, the crispness of a sax or in the decay of a drum beat..."

In fact, these complex and unique resonance and damping properties are what makes maple valuable for certain applications in acoustic instrument manufacture.

See this exert from "Tapping Tonewoods", by Dana Bourgeois

"How the Selection of Species Helps Define the Sound of Your Guitar"

Acoustic Guitar Magazine, March/April 1994

"...Maple and walnut tend to be more acoustically transparent than other tonewoods, due to a low velocity of sound and a high degree of internal damping. That is to say that they allow tonal characteristics of the top to be heard without the addition of extraneous coloration and may even serve to attenuate some of the overtones emanating from the top.

The harder, denser examples of these woods, such as sugar maple and black walnut- particularly quartersawn examples-tend to lean slightly more toward the tonal direction of mahogany, while softer examples, such as bigleaf maple and claro walnut, tend toward greater tonal transparency. Curly, quilted, or bird’s-eye figures do not seem to have much effect on the tone of the wood, but they can be used, like bearclaw, as an indicator of other properties. Quilted figure, for example, occurs most often in softer species and is best displayed when the wood is flat sawn-two characteristics that tend to produce higher damping properties..."

So I surmise that, in addition to wood type, thickness, mass and angle of cut of the piece of wood will alter the way the wood responds to, absorbs or resists vibration. Greater thickness and mass means greater energy required to get a maple or other wood platform to resonate. Thickness plus cut can also increase the internal path length, and the number and configuration of wood fiber bonds available to dampen vibration. That's why guitar backs aren't four inches thick! For some applications, a thinner platform may be better because the resonant frequency of the wood actually enhances the perceived performance of certain electronic gear.

Maple isn't really all that hard, IMO. The vibrations that enter the platform are bounced around and some converted to heat within the wood. With most butcher block platforms there are many surface boundaries which effect the waves traveling through the wood. This causes even more scattering, but there is also attenuation as some of the energy is lost in the reflected wave. Eventually, things settle down.

The butcher block I used caused a smearing of the midrange that resulted in loss of detail and too much warmth. I may try a solid chunk sometime, but I suspect it will still be too warm for my preference.

There are many folks using big hunks of maple as shelves and I'm sure it does work in many applications. But obtaining better sound by using maple is no guarantee.

And those spikes that folks think act like some kind of mechanical diode, well it doesn't work that way. The spikes provide coupling which means vibrations can travel in both directions. They can be effective in some cases and detrimental in others. In general, spikes help emphasize bass and devices like rollerballs (non-compliant) help emphasize air and space around instruments. Products like Stillpoints are somewhere in between as they have both high-rigidity and some compliance. Personally, I have better luck getting the sound I want by using these kinds of products over what material the shelf is made from. YMMV, and all that.

Steven, FYIF, many baseball players have been using maple bats for years now. In fact, the maple bat seems to have taken over those bats made of ash.

How thick should this maple platform be?