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Want to build a rack with sandwich layered dampening

Hi all,

I considering constructing a very basic, small, low two shelf rack to accommodate my somewhat compact components to replace my rather resonant Pangea rack. Lower, not as deep and a bit wider to accommodate access, but also keep it low to preserve stage between the speakers in my smallish listening room. 
 

I’ve found some perfectly sized and precut maple (I think it’s maple will have double check). 3/4 to 1” boards that I’d like to sandwich together with screws, and place some sort of elastomer material between to control resonances. The legs would be basic but thick, and I’d probably just put spring isolators under them. Rack would be sitting on a raised hardwood floor. 
 

My question: would using a sheet layer of sound absorbing butyl or some type of elastomer in between help or potentially harm sonics? Reason I’m asking, I’ve found sorbothane to actually have an adverse effect under components, with say stack audio pucks instead a purely delightful improvement. I know we’re talking about a different application, but still would like to get some experienced thoughts on anyone that has done - or purchased - something similar. 
 

Big thanks in advance for anyone’s help! 
 

John 

riccitone
terry9
2,327 posts
 

Constrained layer damping works by having two materials of different acoustic impedance in intimate contact.Wood and elastomeric glue are quite different, but you may fare better by using one layer of wood and another layer of metal, joined by elastomeric glue: aluminum and lead are two of the best choices.

When I built my music room a few years ago, I looked at many of the elastomeric products, and found M1 from Chemlink to be a good all-round choice. They also have a product which has marginally better adhesion - but look at the specs of anything you use, because some of the stuff called 'glue' really isn't.

Good luck!

terry9
2,327 posts
 

By the way, lose the screws! Metal fasteners transmit energy very efficiently from one layer to the next, undoing most of the good which constrained layer damping can do. Other fasteners connecting the two layers aren't much better.

dmk_calgary
117 posts
 

Another option would be to build bases for your equipment. I used the material that @bdp24 mentioned, and sandwiched that material between oak and granite from my local kitchen counter store. My amp and pre-amp and TT are sitting on those, which, in turn, sit on the stand. The TT is on its own supports on the wall studs. As someone else pointed out, constrained layer damping only works when you have two DIFFERENT materials - so I used granite and wood. YMMV of course.

brunomarcs's avatar
brunomarcs
272 posts
 

I took some 4 pound lead sheet and covered both sides with dynamat extreme. I have 10 of these on my rack under the shelves sitting on a layer of exterior grade mdf, it's called extera, a little denser and has epoxy resins or other waterproofing elements in it, it was free OK. The rack must weigh 350 pounds. I cant  possibly move it, need to put wheels on it somehow. 
 

Im gonna use lead sheet again on a TT plinth.  I'm not worried about getting lead poisoning because it'll be completely covered. 

mesch
3,469 posts
 

Use thin cork material glued between between maple wood layers.  

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