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Turnable Rack Vibration

Hi,
I recently moved my Audio equipment to a VTI rack system. As part of the change by Linn LP12 moved from a Target wall shelf to the top shelf of the VTI.
The move has made the turntable far more susceptible to floor and foot fall vibrations... disappointingly and annoying so.
I would like some recommendations on effective vibration isolation for the turntable chassis. I have a 1/2" slab of granite that i am thinking of placing the turntable on and separating the granite from the top shelf of the rack with a series of isolators.
Has anyone had experience with this setup and what isolators would they recommend?
Of course i am also open to any other suggestions on how to best isolate the top shelf for the rest of the components.

Thanks
Neil
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nsgarch's avatar
nsgarch
2,524 posts
 
TT's in general, and especially ones w/ floating sub-chassis like the Linn, are always suceptable to bouncy floors. I don't care how good/expensive a rack or isolation platform, when it comes to external vibrations, they will bounce right along with the floor, period.

Unless your house has a nice thick concrete slab-on-grade floor, or you live in an old factory loft with steel-reinforced concrete floors, your best bet is a wall shelf.

And there is no way to take the bounce out of a wood joist floor except to tear out the floor ad rebuild it with deeper, more closely spaced joists, and/or provide an intermediate support beam underneath to reduce the span of the existing joists to half their present span.

Neil
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islandmandan
1,260 posts
 
I have a modest analog front end, but I have been able to maximize it's performance with isolation. You may be able to use your granite slab to do this. I use a Brightstar Audio BigRock2, (a sandbox, basically), which is supported by four steel coil springs. I am using a wall-mount support, but I believe it will work on your stand. I installed brass spikes to drain vibration into the box, but in your case, more isolation between the plinth and sandbox might be the better approach. It sounds strange, your table being supported on springs, but you soon get used to the motion when touching the table. I do think in your case, the sandbox might be indispensable.
If you try it, I think you may be surprised at how much relief you will get.

Regards,
Dan
nsgarch's avatar
nsgarch
2,524 posts
 
I think most folks are unclear about TT isolation/absorbtion. Things like spikes, roller blocks, Stillpoints, iso-platforms, etc. will drain away vibrations created by the TT mechanism (and I suppose the cartridge itself ;--) but these values should are hardly even measurable. Certainly not if the TT has decent bearings and motor drive. Vibes in the actual vinyl record created by the stylus should be damped by the platter (mats and/or clamps are what you want for that.) Vibes and impulse energy coming TOWARD the TT (like from foot falls, or bouncy or resonanating floors) are VERY hard to stop and here's why:

First these vibes come in all different frequencies and no one material --springs, sorbothane, hydraulic damping feet, rubber bands (like on the SME) -- can block them all. In fact, some of them can do more harm than good if they happen to naturally oscillate at one of the incoming frequencies!

And second, any mechanism that would have a low enough resonant frequency would have to be so big as to be impractical in a home environment. Just look, for example, at those HUGE spring frames in which they suspend (relatively small) microphones in recording studios. Can you imagine a turntable-sized contraption!?

That's why we have wall shelves ;--) I have seen a few audiophiles construct concrete block piers, or pillars, filled with sand, right on top of conrete slab floors in their listening space(s). However, it does require an extraordinary commitment to the location, ha, ha!
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islandmandan
1,260 posts
 
All very good points, Ns. The wall mount is the easiest, most effective (for the price) solution. I considered it worth a try in Neil's situation, first without the wall-mount. I have seen this method used on top of racks and table supports that were located on the floor. The supplier of the information insisted the isolation was effective. I know only that with my installation, the results have been superb, the arm and plinth drain into the Brightstar, and the springs isolate the table. The wall mount is however, a major contributor to its sucess.

My judgement is that it is worth a try, not much cost involved, and may be retained and used in the final solution.

Regards,
Dan
nsgarch's avatar
nsgarch
2,524 posts
 
I guess my point is that any top-of-shelf/under-TT treatments, if they appear to work, do so because you already have a rock solid floor, and a rock solid rack (like a Billy Bags TT stand.) But if you have a bouncy floor, it's just going to take the rack and all that other stuff with it.

To me, a solid floor is everything, and when the floor can't provide it, then you need a wall shelf (and hope and pray that the wall doesn't vibrate!)
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