Gatorboard or Owens Corning 703/705 might be lightweight contenders if you are considering a constrained layer type platform/shelf and are looking for a vibration damping layer between the wood and a steel plate. However, I may not be visualing your intent. The burl in the picture looks thicker than 0.9 inches but there is nothing to denote scale. It sure looks nice!
Building a custom isolation equipment rack
I’ve finally managed to get to doing something about an equipment rack for my system. Hoping to make a low level rack, with two shelves to keep it lower between the speakers. It may not be optimum, compared to having it out the side, but the idea that it is low enough to at least not be center of the sound field for imaging sakes.
I went and purchased $600 of pretty clear mesquite burl 1" boards (there will be minimal epoxy). And so I’ve already taken the saw marks off both sides, and I’m already down to 0.9inches thickness.
When I worked for Lenehan Audio in Australia, my mentor Mike made many isolation racks for equipment, laminating wood and steel plates and using springs.
I would like to incorporate the springs I purchased for that task under my two shelves. I have a weight goal for the mass loading of the springs, and I need rigidity, without adding too much more mass.
Steel was my first thought, but it would be both heavy and have a possible dielectic impact (okay so I’m possibly/probably paranoid).
I’m looking at using a honeycomb structure under the top to support it by laminating it with the mesquite, honecomb and then maybe carbon fiber?
Anyone in the forum worked with honeycomb or that sort of thing?