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
extra_action
Having faced this issue countless times, the only technique that consistently works is to fasten a 90 degree shelf bracket (which you can buy or fabricate yourself) to the top shelf at the back and to the wall. This will cure 95% of the problem.

Failing that, even wedging something between the wall and the back or the rack/shelf can help a bit, until it falls. :)

A vertically suspended turntable such as a Linn on the top shelf that is susceptible to footfalls is actually having to contend with some horizontal movement, which it cannot handle.
Hornguys, you are talking about what's generally referred to as a "tie back"; tying the top of something that's swaying, like an equipment rack or a tall panel speaker, to something that isn't swaying (we hope) like a wall! This can be a good solution. It depends.

Let's take racks first. If a rack is on a concrete slab floor and it still sways, it is a poor design. The worst offenders are the threaded rod type, because the rods themselves aren't fat enough to resist bending and there's virtually no moment resistance in the rod/shelf connection. There is a way to cross brace these racks, but for the time and money involved, sturdier racks are available for less money.

If the rack is quite sturdy like a cheap Studiotech, or a pricey Billy Bags, it can still sway left-right, or front-to-back on a joisted wood floor. L/R if the joists run perpendicular to the wall behind the rack, and F/B if they run parallel; ditto for loudspeakers.

Speakers should not be allowed to sway F/B even a millimeter (at the top) because it can ruin transient response. If a speaker sways a little bit L/R (joists running perpendicular to the wall behind) it's not a big deal performance wise.

Unfortunately, the tie-back solution is mostly effective against F/B movement. Much less L/R movement, and not at all for vertical movement. I have my MartinLogan panels on Sound Anchor stands which have triagulated bracing (see system) but before that, I had their tops tied to the back wall by a 6 foot length of 3/4 inch white PVC pipe. The improvement in soundstage and lyrics intelligibility was amazing!
My previous apartment had a cement floor, so I never had a problem with my TT on top of the rack, but I moved into my girlfriend's pre-war apartment and I got bad vibrations if anyone walked near the rack.

This past weekend I put up a Target Pro shelf and it works great- you can jump up and down and nothing happens. I recommend going back to the shelf.
Hi Hdm!

Hdm -> "Kenny: When you say the Target Pro shelf "flexed under the load" are you saying that the rack itself flexed or the shelf material (MDF shelf)."

Yes, the shelf itself flexed and I was within the maximum weight load. It's possible that the shelf was defective but I did not get a response from Target. If you email me I can send you pictures.

Previously, I had used an older Target shelf with a SOTA table but I needed the Pro shelf to accomodate my new table. The old Target shelf never flexed but it was designed differently.

The flexing scared the "%@#!" out of me and I didn't care for the sound. I could not adjust the front leveling screws to bring the table up to level. The pictures are very revealing.
I earlier in this thread recommended the Target wall shelf, only bcause it works, and it's cheap (relatively). To level the top shelf, I placed a 3/16" thick! steel bar behind it, with a backing of sorbothane. It pissed me off, I thought the damned thing was made in England, maybe it is, but whoever built it did a piss-poor job if it.

Dan