Sandbox-style isolation

Do you really believe that the top plate segments will move relative to each other enough to cause even tiny shifts in geometry of drive train

Yes.

Based on the argument that these two pieces won't move independently, one could argue that isolation of any sort wouldn't help because all of this movement is so minute.

Ultimately we are all patently mad and arguing over small things, but as long as we're having fun with it, let the debate rage on.

Cheers,
Thom @ Galibier

Assuming that significant mass loading has been applied to minimize shifts of the segmented top plates in the horizontal plane, the heart of the matter would seem to be that vibration is conducted through dense adjacent solids--in this case, mechanical energy moving in the vertical plane from plinth to footer to wood plate to sand. In a related twist, tonight I modified the suspension of my modified thread-drive VPI TNT to incorporate DIY Stillpoints inside the elephant feet (which are otherwise unsprung.) The mod consists of a pyramid of ceramic balls, supported by spring steel petals that dissipate vibration of the bottom tier of balls into the horizontal plane as mechanical energy. The result was a rather amazing improvement in coherence and general sonics. The operation of the ball/spring combo would seem analogous to grains of sand beneath the sandbox plates, but in the horizontal rather than vertical plane. Now I will bet my eye teeth that those balls & petals in the Stillpoints are by design moving more in the horizontal than the segmented plates in the sandbox-- and yet sound is significantly improved. You would have to put up a pretty strong argument that the improvement in sound represents a compromise between improved resonance control and degraded speed stability.

Dave, the sand should move in both the vertical and horizontal plane as well,

It still seems to me a mass loaded design should sit on the most stable platform you can provide, seems some non-sympathetic vibrations would be induced by more compliant platforms. Therefore, vibrations of different parts of the tt are moving asynchronous to each other, inducing confusing movement to the entire mechanism. Sitting on segmented plinths should only increase this confused movement.

I should add, every move I've made towards a less compliant plinth and more massive platform has resulted in increased sonics, specifically, much more coherence, solidity, slam and bass articulation. Any compliance sounds smeared and soft.

I plan on making a 10" sandbox this summer to gain yet more stability and mass. I'm also trying to find some wider aluminum L brackets in order to get more vibrational drainage. I always think about the massive plinths and platforms of the Brinkman and Continuum tts, I'm sure a lot of their superior sonics come from this mass and the stability it imparts.

"Any compliance sounds smeared and soft"

Lest the good folks misinterpret your comment, I'll embellish a bit.

The improvements rendered by reducing compliance result in both cleaner and more extended highs. There is nothing agressive sounding about the extended top end when you get this right.

Furthermore, the improvements are experienced as a richer, harmonic texture in instruments like acoustic bass. Bass texture is, after all about the upper frequency harmonics.

Again, it may well be that on some rigs, that isolating the motor can help in the way that a compliant belt can. Before you accuse me of heresy, hear me out.

In some AC motor experiments our little group of crazies has been undertaking, we positied that some of these drive systems might best be implemented with a compliant belt. There was too much vibration in the system.

Of course, we were looking at optimizing something that none of us would consider swapping out our rigs for, but the point is about trying to optmize given architecture.

There are no hard and fast rules. This was the source of my "ecosystem" comment and is the reason I'm not absolutist about one piece top shelves for the entire population of turntables.

I'm working on a source for some very stiff "L-brackets" which I used to source at an aluminum recycling yard. When I get the name for them, I'll publish it on both the shelf and stands FAQ section of my website as well as on the accessory page showing the sandbox made by Timber Nation.

Now, if you hang out at any electronic surplus houses, you might find some big honkin' heat sinks. I've come across some which are 6" x 8" and have some under my main sandbox.

Cheers,
Thom @ Galibier