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Turntable and Rack vibration control

Hi,
I moved from a Nouvelle Platine Verdier to a Loricraft Garrard 301. The big change with this move was that the Verdier comes with a terrific implementation of pneumatic suspension feet which kept the TT almost floating and hence great isolation from vibration. The result was always a noise/grain free playback and super clean backgrounds. With the Garrard, the plinth is typical custom made stacked birch ply with standard steel cones as footers. When placed directly on the rack the background is noisy, the images muddle up and overall music is not well sorted.

I do not expect the Garrard to be as quiet as the Verdier but I know it should not be this noisy either. In fact the Verdier also sounded noisy when I placed it directly on cones bypassing the pneumatic suspension feet. 

I use a Hutter Racktime rack which is not like an overbuilt audiophile rack. It is more like an open frame rack with lightweight supports. It is a bit like a Rega TT, not very damped or controlled. The rack has pointy steel feet which rests on brass spike plates (mine is an wooden floor). I guess this implementation is not sophisticated enough to keep away vibrations and let the TT play quietly. 

I am looking at two levels of solutions:
1. Replace the existing steel feet and brass plate with a quality vibration control footer below the rack
2. Replace the stock steel cone below the TT plinth with a better footer/platform.

I have tried Sorbothane, Squash balls kind of tweaks, while they reduce noise they slow down the music too.
I have also tried Stillpoints and Finite Elemente footers under the rack. They make the sound thin and metallic IMO. Platforms like Minus-K are too expensive so I have not considered them yet.

I am looking suggestions here, probably footers and vibration control devices that are more musically oriented yet well engineered like Shun Mook, Harmonix, SSC or something like an HRS platform ?
pani
jollygreenaudiophile2's avatar
jollygreenaudiophile2
275 posts
 
    Pani?, There "is" actually a scientific way of calculating what in general you would need for a plinth. And they are not just for vibration. Just as your turntable woe's probably aren't simply due to simple seismic vibration. And if you have a flooring problem, that can only exacerbate things. What kind of rack system are you using? A bad rack can amplify small problems also. I recently bought a VTI BL304 with isolation between every shelf and you can fill the legs with sand or shot for mass loading depending upon what you are trying to do. It works and It looks quite nice as well.
    I've been experimenting with not only isolation but damping "not just vibrations, though I do with a laser accelerometer." and insulating. Also filtering and field barriers for awhile now.
    A wood plinth will help but a hybrid plinth is even better. Utilizing layers of protection against all kinds of unwanted distortions. Brass of certain types, "en mass" can clear your turntable of outside free harmonic resonances between 5K and 6.5K. Iron Ferrite cores, sheets and plates can have a role as well with getting rid of HF trash as can Corian and Acrylic.
    And in the end it's all subjective to the sound you want to tune your system too! I recently made a plinth from "Leopard" wood which is 49% more dense than Red Oak. And all that Jazz about maple always being the best wood to use went right out the window.
     If you'd like to learn a bit more I can steer you towards a few things. Try looking up "Parasitic modes of vibration" and their effects on amplification. This effects everything from your cartridge's tip all the way down the sound path to the output stage of your amplifier and beyond. All this according to the studies I've read about JUST, "Parasitic modes of vibration"!
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haroon
16 posts
 
@geoffkait

It seems you have not used the free App, "iSeismometer" yet; try it you’ll love the app. I suspect your math is not correct about accelerometer, app and its effectiveness. You may try other apps (not free) and they will even tell you frequency.
jollygreenaudiophile2's avatar
jollygreenaudiophile2
275 posts
 
The only problem with using any app. is the fact that no matter how fine the code is written, at the end of the day your still at the mercy of whatever your using collect data. In this case, conduct the vibrations to your device. All vibratometers I know of come with a dedicated "probe" just for vibrations. So what your doing is basically trusting the 23 cent microphone in your phone. Would you trust a frequency analyzer app to do room correction? If you do your probably going to have a dead spot below 40 Hertze. Why? Because your phones mic cannot read at that level. And then there's the accuracy. Ha ha, I wont even go there. Do you see my point?    And I do trust my math. The last time I looked 2+2 still equals 4. So there IS that!  Now, let's say you've spent the $1,500.00 bucks on the dedicated probe. The resolution of given app is about enough to tell you if there is a minor earth tremor or not. Not quite what you'd need to measure the nano-vibrations that are affecting your turntable, amp or Pre.   If this was THAT easy everyone would be doing it! And I'd be bored.


pani OP
1,219 posts
 
I tend to agree with @jollygreenaudiophile2. I tried the iSeismometer app on my iPhone. It shows very very minor vibrations in the z axis. But the reading looks the same whether I place the iPhone on the TT platter, plinth, rack or on floor. No difference in reading which only goes to show that it is not sensitive enough to measure the differences in vibrations between these surfaces. Something much more sophisticated would be needed. 
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