Sandbox-style isolation

Hi all,

Isolated segments of a top plate come at a cost - that of maintaining the correct speed relationship between the drive system and the platter. You might get better isolation, but it doesn't come for free.

In Galibiers (and by inference Teres, Redpoint, and ???), every time the coupling between motor and platter has improved, so has the sound.

Now, just like rubber belts in some designs, the net result can be an improvement. I think what we're looking at here is: (a) how much vibration you're sinking, and (b) does any of the movement inherent in this isolation strategy get masked by any compliance in the belt.

The bottom line is that there are no absolutes and the entire system needs to be considered as an ecosystem. What works in one context will not necessarily work in another.

On a related subject (and one I feel more absolute about), from time to time I find myself working hard to convince customers to NOT site their drive system on a separate stand from their turntable.

Picture two sky scrapers independently swaying in the breeze, and I think you can visualize the nature of the problem. Since no two areas on a floor vibrate identically, the two stands will move out of sync with each other. The higher the stand (in relation to its width and depth), the more this is exacerbated.

That's my story and I'm sticking to it ;-)

Cheers,
Thom @ Galibier

Cheers,
Thom @ Galibier

Thom, Segmented top plates sharing a single sandbox, each segment with an alumimum angle or aluminum heat sink anchored deep into the sand. Heavy mass-loaded plinth with heavy outboard motor. 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?

I can tell you from my own experience the single aluminum plate using the vibration sinks, per Thom's instructions, is superior to the segmented top plates I've tried. More refinement, resolution, more slam, solidity, greater dynamics. Now, I've thought about segmenting the aluminum plate, Thom's argument makes sense, I will not segment.

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.