DIY stand questions in regards to shelves and supports for high mass

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I need to build a two-level stand for two high-mass items. On the top will be a turntable that weighs in at 70 or 80 pounds. This will sit on a sandbox with maple plinth that I'm ready to build now, will be large (wil be 26.5 by 21 inches or so, probably 5 or 6 inches tall), and that will be heavy (sand, duh). So that's maybe 120 to 130 pounds on top of the table. On the bottom shelf will be one of my tube amps (Music Reference RM9). That is 60 pounds, and will either sit on a sand box (figure another 40 to 50 pounds) or a granite slab (figure 70 to 80 pounds.) So I figure this thing has to support some heft, but perhaps the heft will help deaden the stand, so to speak.
First off, shelves...I am afraid of eventual warping and support, so I'm wondering if I go MDF a) will 1.25 MDF be thick enough (it will be 26.5 by 21 inches) to support the 130 pounds on top or should I B) use two slabs of mdf to make it 1.5 to 2 inches or C) a sheet of .75 to 1 inch mdf and some 3/4 inch hardwood or ply on top.
Or should I go hardwood instead?
Or a composite? Say, .75 MDF, some cork. PE foam or blue tack sandwiched between the MDF and a wood/ply top? Simular to the Symposium clone. I'm figuring, though, that since I'm going to be using sandboxes (or a sandbox for table and granite slab for tube amp), maybe the extra damping on the shelves would be a waste.
Now, support legs. What do you think of A) thick, 1 to 1.25 inch threaded rods (24 inches high, they have these at the hardware store), with bolts and washers simular to the flexi rack, though it should be sturdier, because it's only two shelves and will be monster sized rods. If I go this route, would three legs be strong enough to support the rack (easier to balance)? Also, instead of threading the thick rods through the top shelve, think I would be ok drilling halfway into the top shelf (figure it will be at leat 1.25, but might go for 1.5 to two inches thick), then forcing the rods into the holes. That way, I don't have bolts coming out the top, and I don't have to get into countersinking (I have a limited amount of tools, I'm building this in a NYC apartment.) I would like the top shelf to be flat, so that the sandbox for the table covers it completely. Have also though about having the bolts come through and having the sandbox sit on the top nubs of the rods, though I figure this might compomise performance of the sand box.
Or...simular to the Enjoy the music speaker stands (I'm also about to try those), I use 2.25 inch PVC pipe as pillars, fill them with stand. Would look a bit massive, but maybe the sand-filled PVC pipes would dampen better than the 1.25 inch rods (though I would think the sandboxes for the gear should do a pretty fine job of damping the components.)

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Topic - DIY stand questions in regards to shelves and supports for high mass - mark maloof 12:25:35 02/02/04 (4)

Re: DIY stand questions in regards to shelves and supports for high mass - Jose Garcia 17:19:54 02/02/04 (3)

Re: DIY stand questions in regards to shelves and supports for high mass - Larry 08:40:37 02/03/04 (2)

Re: DIY stand questions in regards to shelves and supports for high mass - Cougar 21:54:07 02/04/04 (1)

Do you rememeber if he was the original... - Jose Garcia 06:17:32 02/05/04 (0)

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