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. |
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. |
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.
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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. |
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.
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I am on hardwood pine with sub floor, suspended above a basement. Rather than industrial overkill, I did nothing to the floor. If you want an electrical ground, you get that when you connect the TT. I have a quality equipment rack that provides some damping. The rack is directly behind the right speaker, like three feet. I then mounted a maple slab from: http://www.mapleshaderecords.com/Your Dawns Depot is a cutting board. I've had one and sent it back. The Mapleshade slabs are made by audio people for audio people. It's not a cutting board. I have a 4 inch one under my VPI Prime Signature and I am very pleased with the damping as well as the warmth of the maple. The four inch is best, but the two inch will do quite nicely as well. Cutting boards have more pieces glued together, the slab is made of 4 inch blocks so the damping is better. Good luck on your floor rebuild. Btw, what will you do when you sell the house? |
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Sometimes you have to take a step back and reconsider your
options.
I certainly give you credit for creative thinking but as a few already
pointed out stabilizing your floor structure is straight forward
and cost effective. My method also.
Proceed upwards from there.
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Robes, do you know the difference between the conscious mind and the subconscious? An example of possible mistakes made by just thinking would be: You sit in your house, thinking of a car tune-up. First, you think I will do an oil change, then change the spark plugs, then adjust the dwell, and on and on. You then go outside, and you can't even get the nut off to change your oil-so, all that other thinking was a waste. I think you have to test out all ideas, one at a time, rather than speculate on things(for instance, maybe coupling to something heavy doesn't work whatsoever, so that idea would be mistaken, and everything else based on that idea would also be a mistake.). This is just an idea on the pitfalls of thinking consciously only. |
@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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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-
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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. |
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. |
You could even use a bunch of adjustable lally columns / post jacks. |
I agree with the other posters in that the structure will be unstable. You will need significant cross bracing. Why not just support the floor from the crawl space below and use a quality rack? |
If I understand you correctly, there will be a mass cantilevered about 10 inches in each direction, supported by 3/8" effective steel pipe, a 27:1 ratio. Sounds unstable to me.
Noromance has a good solution. Even better would be to do exactly as you suggest, but on each of three or four corners.
But don't forget about rats and mice and ants and ... all around that pipe.
Just my opinion. |
Sounds like your TT will sway around like the Empire State in a storm. Why not build up a stone foundation under the table location and bolt the floor to that? |
I also have suspended hardwood floors. I use a VPI Turntable stand filled with sand. On top of that sits a 3" maple shelf sitting on spikes. This works really well for me. The stand filled with sand is very heavy and stable.
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Sounds like a very good solution to the TT vibration problem. But, a lot of work. FWIW I use a Core Audio PlyKraft 3L stand with my TT, see my previous post on this subject. The stand sits on a suspended wooden floor. It doesn't matter what I do (high volume, dancing, nudging the rack etc.) the cartridge never skips and there is absolutely no feedback. Works for me and the Core Audio stand looks beautiful IMHO. |
Congrats on your new TT and further congrats on your very inventive solution to vibration issues.
What you propose should work at preventing floor borne vibration from reaching your TT, but so would shelf mounting. How do you know you have a serious footfall problem?
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