Where is Your Turntable?

I posted this in another thread but it might be helpful in the context of this thread, too.

When attempting use of a wall mount rack, be careful before drilling holes and positioning other associated equipment (regardless of table). Room nodes can be an issue - a serious issue. I built a wall rack using 1000lb rated Stanley brackets and a 3" rock maple base. I positioned where I THOUGHT I'd be okay and attached straight into wall the studs using SIX 3" lag bolts. The floor was a poured concrete slab. As one increased gain, the air borne resonances caused a terrible rumbling mess. Touching the wall near the supports - rock solid, not so much as a trace of vibration. Further out on the base - different story. Moral? The rack can be mounted like a pillar and while you can eliminate floor vibrations and all but eliminate wall vibrations, those air borne forces are much greater than one would think. A two foot repositioning solved the issue entirely, but the six holes required filling and repainting in the process.

Does anyone know a way to eliminate this air-borne effect if someone were locked into an otherwise poor position for a wall mount without moving it elsewhere?

4yanx -- is there another wall, right behind the first one your wall shelf is attached to, that joins it at a right angle just to the right or left of where the wall shelf is?? (I hope I'm right on this one!!) What might be happening is the horizontal vibration in the first wall (created by the sound waves) creates a twisting motion (rather than just back and forth) around the point where the perpendicular wall joins it from behind, creating more motion out at the front of your wall shelf than at the back where it joins the wall. Placing the wall shelf right over that point would be the best place. Just a wild guess!! :~)

Although I'm an advocate of wall shelves for TT's, a big, expansive stud wall, using 2x4 studs 16" apart can vibrate like a bee's wings! Then, the only usable location is near a corner or adjoining the fireplace (unless you can figure out how to brace the wall from behind.) In those cases, if you're on a concrete slab, I say get a great sand-filled turntable stand with spikes biting right into the concrete.

No, it is an outside, load-bearing wall with no perpendicular walls, though I understand your point. Built in the 50's it has 16" spaced studs AND angular bracing between studs (I know because I stripped off and replaced old knotty pine paneling!). So, wall vibrations were really not the issue in this case. Moving the rack 2 feet fully solved the issue, so I was always under the impression that air-borne vibrations were, indeed, the culprit. I can set a glass of water on the rack now at cranking volume, without so much as a ripple on the surface. I now use the wall rack for one table with two other tables sitting on sand-filled Osiris Giza amp stands. They all sound equally good, can't pinpoint any benefit of one placement over the other.

Well then 4yanx, there can only be one other explanation -- termites!!

Hre in Clifrnia, tht can alwys b a pssble isu.