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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
desktopguy
378 posts
 
Your anti-footfall solution is massively engineered and will no doubt work. Far be it from me to discourage such an innovative & effortful concept.

However, I suspect the following would work just as well. This is something I planned to do based on a product that used to be sold in the '80s (for all I know it still exists):

1 - Using any wood of your choice (3/4" thick stock or plywood), build a study open-topped box ~2 ft wide X ~ 5-8" tall 18"-20" deep (exact dimensions depend on outside dimensions of your new prime, measured from outsides of foots or other support structure). The end result will look like a wide/relatively thin box laying on one of its large surfaces--but lacking the parallel large surface to "close" the box

2 - build a sturdy 3/4" thick "floating platform" (single piece of wood) that is sized ~1.5" smaller than the outside dimensions of your open-topped box. This piece of wood will "float" on top of the box, representing an approximation of that missing top surface

3 - fill the box w/play sand to w'in ~5/8" inch of the top. 

Just place floating platform on top of sand; then the Prime + any supporting footers/structure goes on top of the platform. This design pretty thoroughly isolates the outside world from the Prime (ie, any non-airborn vibration that might hit the prime from below). If the platform or structure on which this new box rests is itself well made & isolated (ie, steel cantilevered structure attached firmly to wall studs for wall-mounting)--the isolation should be quite good overall.
andrei_nz
192 posts
 
An interesting project.  To have a great TT you need great speed - easier said than done.  You also need great vibration control - also easier said than done.  No wonder the high end is so expensive.  There are may vibrations.  Most of them are like germs - you do not see or feel them but they are there.  To make a list: 1. Ambient vibrations in the room 2. Footfall. 3. Sound waves from the speakers. 4. Stylus colliding with the vinyl. 5. Friction of the bearing on the thrustpad.  They are all deadly because they get magnified some 10,000 times by the time they come out of your speakers.  Your solution will address 1. & 2.  My advice is to not forget the other causes of vibration.  
I myself do a little bit of this and little bit of that: Aftermarket feet ;(Isonoes); a PEEK (species of teflon) thrustpad; Mass (granite slab); Platter Damping (epoxy under the platter, quality mat, dynamat on unseen parts of the chassis).  Finally those vibrations that cannot be reduced or damped are 'tuned' in an attempt to sound benign.  So I use ebony - they make oboes and clarinets from the stuff.  Ebony stabilizer, ebony armboard, and ebony headshell.
testpilot
952 posts
 
Using cables attached to the house foundation to provide support for the verticals post will in affect provide a path for addition vibration to be transferred to your rack.  You need to internally brace the vertical supports to help isolate the rack from the external environment. To understand the importance of internal bracing, all you need to do is look at the amount of bracing provided by the leading audio stands. You could always internally brace your support stand by adding a series of shelves. 
bsavage
27 posts
 
I have a VPI Classic 3 with the Symposium Classic Footer Damping Insert kit. My listening room is on the second floor above the garage with no supports underneath it but the floor joists. When I would place the stylus on a motionless record and walk across the floor near the equipment rack, I could hear my footfalls through the speakers. Tapping on the side of the equipment rack would also produce fairly pronounced thumps through the speakers. 

I installed the Symposium Segue ISO Platform on the top shelf of the rack under my Classic 3 and now experience no sound through the speakers at all when jumping up and down on the floor in front of the rack with the stylus sitting in the groove of a motionless record. Tapping on the side of the rack still produces a faint sound from the speakers, but I would estimate it is reduced in output by 80%. 

The Symposium Segue ISO is a very easy and quick solution to implement and in my situation does a fantastic job of isolating the turntable from footfalls and most other external disturbances. I highly recommend it.
artemus_5's avatar
artemus_5
1,982 posts
 
I'm late to this thread but hopefully helpful. I am a builder with 50 yrs experience. 2x4's are your friend. They are plentiful and cheap. I reinforced my floor where the stereo system sits. Speakers weigh 135 lbs a piece. Turntable weighs over 100 lbs. It is atop a sand box which is part of a custom made rack which has concrete inside the legs. 
Under the house you just need to put some 4" solid blocks down on the ground. Or put them down in a hole. These act as a foundation. Saves time with concrete which isn't necessary. Span 2 floor joists under the stereo system with a 2x4. Put a 2x4 upright up to the spanner board mid way between the joists. Do this on 3 ft increments. That is plenty of reinforcement for a 2 x 10 floor joist system. If 2x8 system, use 2 ft increments. I can jump up and down in front of my TT while its playing.

Remember, the floor system has been engineered to withstand standard foot traffic. Consider that you have a refrigerator in your kitchen which weighs 300 lbs and only has 6 sf to carry that load. So its not like you have to engineer from scratch. You just need to reinforce whats there. My ScoutMaster worked great on a sand box.
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