Turntable on suspended floor - shelf or braces?

Hi djm,

My living room has a suspended wood floor with 20' spans for L and W. A closet, enclosed stairwell and fireplace column on one wall prevent the dreaded "square room" for sonics. But the long span meant bouncy motion even when walking light-footed. I had a heavy cabinet placed by a sidewall but the suspended table still bounced the arm/stylus whenever anyone moved around the room.

I too have a crawl space so I installed three 4x4 posts on concrete footers at 5', 10', and 15' along the center axis of the room. My floor joists run perpendicular to the line of the posts so that helped distribute the support. That cured my floor flex and bouncing stylus problem.

An easier solution might be to mount your turntable support on a load bearing wall. But my floor supports also minimized the floor flex to improve bass response (stiffer boundary) so I gained two benefits.

If you have much flex to your floor it would seem to me any sort of suspension under your table would only be a band aid. Why not cure the ailment instead of taking an aspirin?

Good luck.

djm,

I should have explained that I used an automotive hydraulic jack to raise each of the three floor joists just enough to slip the carefully measured 4x4 posts into place. Then after lowering the jack I didn't even need to nail the 4x4 posts to the joists, but I did drive a couple of framing nails just in case.

Also heavy duty leveling jacks are available for mobile homes, but the three posts and footers were not expensive.

For an easy fix, cram a few paperback books behind the rack or furniture the 'table sits on (as close to the top of the rack as possible) so that the wall will essentially brace the rack and keep it from moving too much as the floor bounces. The more tightly you can wedge the books in there, the better. Fremer mentioned this somewhere on Analog Planet, and it works.

Ablang.....yes - very effective.

Not sure is this is relevant, but I bought an older but clean Linn table a few years back and stuck on top of my rack where it was NOT happy...then (of course) read the "official" manual which suggested a lower firm table and it's worked perfectly since. Low mass, level, sturdy table...done. Got lucky I suppose.