Audio Rack Construction


Happy New Year All!

I'm planning a rack with three wood (maple) shelves using threaded rod as the supports. This will be something similar to Salamander racks. Besides, the metal washers and nuts, I'm going to be using some type of isolation washer that will contact the top and bottom of each shelf.
So...shelf, isoloation washer, metal washer, and then nut.

Questions: 1. When passing the threaded rod through each shelf, should the holes in the shelves not allow the threaded rod to touch, so the only thing touching the shelves are the isolation washers? 2. Besides neoprene, what's a good material for the isolation washers? 3. After leveling each shelf during assembly, I'm planning to add aluminum tubing over the threaded rod and nuts between each shelf for a cleaner look. This would mean that the top and bottom ends of the aluminum tubing would also contact the shelves. Should I avoid this, or additionally add some isolation material between the ends of the tubes and the shelves?
kennythekey
I would fill the "tubing" with a material to dampen it.Mine touch the shelving (brass).Be sure to leave enough threaded rod to attach footers.
Alternative: don't use an isolation washer. Keep everything rigidly connected and couple the threaded rods to the floor with spikes. If you're going to uses tubing over the threaded rods, build it layer by layer and fill the tubes with lead shot for mass and damping. Countersinking the area around the hole to the diameter of the aluminum tube with keep the shot nicely contained. This generally is the way the Walker Audio rack is built.
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An inexpensive solution to the isolation washers are rubber O rings I got at a lawn mower shop. They were something like 7 cents a piece. Neoprene and larger flat rubber washers may be better, but it can get expensive when you need 8-12 per shelf.
Check out some of the acoustical parts manufacturers web sites. If I recall, they make some isolation hardware that is used to isolate mechanical equipment from floors. I purchased some of these components in the late eighties when I wanted to quiet my basement furnace units from the floor as I had a media room that I wanted to keep quiet. They were very inexpensive and really worked.