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Advise on TT Support Platform

Hello All-
  This is what I plan to do and would appreciate any comments on my idea. I have (soon to be delivered) a new VPI Prime TT and plan to place it on the 1st floor of my residence which has a hardwood floor. Under the floor is a 5' crawl space with dirt bottom, the house is supported on poured concrete footings & 5' poured concrete walls.

  I plan to drill a 1.25" hole through the floor and run a 3/4" dia. black pipe (gas line) through it. The base of the pipe will be sunk into a 2' x 8" dia hole and filled with concrete while the pipe is centered within the hole with .25" of clearance surrounding it (isolating it) from the hardwood floor. The pipe would further be secured with 3 wire stays on turnbuckles ( as an antenna ) to alleviate any chance of pipe movement. The stays would attach to the pipe near the underside of floor & anchored into concrete foundation walls, then tightened down. The top (terminal) aspect of the pipe would have a black iron pipe flange screwed onto it at the determined TT height.  A 21" x 21" x 3" maple platform https://www.dawnsdepot.com/product-page/dawn-s-depot-maple-audio-isolation-platform-aud21213-21-x-21-x-3  would be bolted to this flange, to which the Prime would set upon.

  Further, I would install the Symposium VPI Prime Footer Insert Kit https://www.highdeftapetransfers.com/products/symposium-vpi-classic-footer-inserts   More on that here also: https://www.thecableco.com/Product/Classic-Footer-Damping-Insert-Kit 

   I'm thinking this will totally eliminate any footfall problems for good and create a internal TT & external platform/TT vibration and resonance grounding pathway to handle those issues.

  So, I'm looking at this as if the vibrations and resonance energies within the TT and those of the platform will be conducted as if they were electrical in nature and simply being lead to ground and dissipated. A note in this regard, my T.V. antenna grounding rod was buried 6' deep in case of a lightening strike in contrast to my 2' concrete filled hole for the 3/4" dia pipe.

  The TT is essentially coupled to the maple platform, and the maple bolted (coupled) to the flange & flange to pipe, pipe to ground.

 Is this sound? or do I have it all wrong?
128x128robes
noromance's avatar
noromance
9,490 posts
 
You could even use a bunch of adjustable lally columns / post jacks.
bdp24's avatar
bdp24
9,471 posts
 
Whatever the nature of the structure, you will want to isolate the turntable from it and terra firma. Cost-no-object via a Minus K table, on the cheap (relatively) by a set of Townshend Audio Seismic Pods.
hwsworkshop
36 posts
 
As noromance says, I would go in the crawl space and install a few adjustable height screw jacks from Home Depot and your floor will never move again.  Probably cost less than $100.00 and should be installed in about 30 minutes.
robes's avatar
robes OP
18 posts
 
Hello All, this is the OP-

  I'm a little surprised about so many replies suggesting the instability issue of the project. I'll try to further describe the build, I wish you could post pics/drawings here that would make my description easier to visualize, anyhow...

  Using the 3/4" dia. pipe, the base of it will be set within a 2' x 8" dia. hole filled with concrete, 5' below the hardwood floor surface into the dirt ground of the crawl space. Moving upward, & at the floor joist level (~8" below floor surface) 3 stainless cables (stays) will be attached to the pipe (at the same level) at 120 degree angles. Two of the cables will run "horizontally" and anchor into the house's poured foundation walls. The walls (5' in height) come to a corner ~2' from the pipe. One of these walls is an outside wall of house, the other wall supports a house beam under the floor (it does not have a wall above it within the home's listening room. These two cables (stays) are anchored & tightened using turnbuckles & will each be ~ 15 deg off of 90 degree angles to the walls.

  The 3rd stay, 120 deg from the other two, will have a "vertical incline (~30deg)" to its attachment to the pipe since it will be anchored into a post hole filled with cement (~10' from pipe) similar as the pipes hole & also tightened with a turnbuckle.

  From the stays point of attachment (to the pipe) to the top end of the pipe (this being the TT's platform attachment site) is about 42"(3'6"). So, I believe we're talking about the amount of sway that the earths rotation will impart on the effective length of 3'6" of 3/4 inch pipe with 44lbs at its apex. Please note, there are no winds/drafts inside the house, no little fingers to clench onto it and swing from it, it is not in an area of traffic or where objects could bump into it. Further, I will be the only one to touch the TT. My cartridge, a Sumiko Blackbird HOMC is very delicate as you know and for that reason alone only the utmost finesse will be used when using the TT.

  I just fail to understand where the "swaying like the Empire State Building in a storm" is coming from? With the mass on top of the effective 3'6" length I can understand if you pushed it, it would "give" some, but sway around, unstable? I also (although I'm not versed in this) think that a little "give" could be beneficial to absorb some man made shock introduced to the TT platform; being beneficial in absorbing impact and possibly saving the Blackbird stylus. There will be no contact what-so-ever with the floor or walls so no vibrations can be introduced that way. I really fail to see that acoustic sound waves are going to create such resonance forces as to start the platform structure to vibrate , sway, or in any way move somehow.

  One easy to do adjustment to the build would be to use 1" pipe rather then 3/4" pipe to add more rigidity and help alleviate any introduced shock to the turntable, how much effect that would have I don't know but easily done without any change to price.

  I have the time to do this. It will only cost 25-$30, a far cry from the simplest shelf or stand and feel it could be better. But I appreciate any further discussion on this project to my latest update here-

Thanks to all who have replied,
Robes-

  
folkfreak's avatar
folkfreak
1,349 posts
 
@robes I think the source of some concern is regarding seismic vibration. Turntables are very sensitive to this sort of interference from construction, traffic or micro-quakes. The arrangement you are proposing risks exacerbating the effect of seismic activity. 

By the way you can post drawings and pictures as part of a virtual system, maybe you can try this so we can see what you have in mind?
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